The long-toed salamander (''Ambystoma macrodactylum'') is a
mole salamander
The mole salamanders (genus ''Ambystoma'') are a group of Salamandroidea, advanced salamanders endemic to North America. The group has become famous due to the study of the axolotl (''A. mexicanum'') in research on neoteny, paedomorphosis, and t ...
in the family
Ambystomatidae
Ambystomatidae is a family of salamanders belonging to the Suborder Salamandroidea in the class Amphibia. It contains two genera, ''Ambystoma'' (the mole salamanders) and ''Dicamptodon'' (the Pacific giant salamanders). ''Ambystoma'' contains ...
.
[ This species, typically long when mature, is characterized by its mottled black, brown, and yellow pigmentation, and its long outer fourth toe on the hind limbs. Analysis of ]fossil record
A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ...
s, genetics
Genetics is the study of genes, genetic variation, and heredity in organisms.Hartl D, Jones E (2005) It is an important branch in biology because heredity is vital to organisms' evolution. Gregor Mendel, a Moravian Augustinians, Augustinian ...
, and biogeography
Biogeography is the study of the species distribution, distribution of species and ecosystems in geography, geographic space and through evolutionary history of life, geological time. Organisms and biological community (ecology), communities o ...
suggest ''A. macrodactylum'' and '' A. laterale'' are descended from a common ancestor that gained access to the western Cordillera with the loss of the mid-continental seaway toward the Paleocene
The Paleocene ( ), or Palaeocene, is a geological epoch (geology), epoch that lasted from about 66 to 56 mya (unit), million years ago (mya). It is the first epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), ...
.
The distribution of the long-toed salamander is primarily in the Pacific Northwest
The Pacific Northwest (PNW; ) is a geographic region in Western North America bounded by its coastal waters of the Pacific Ocean to the west and, loosely, by the Rocky Mountains to the east. Though no official boundary exists, the most common ...
, with an altitudinal range of up to . It lives in a variety of habitats, including temperate rainforest
Temperate rainforests are rainforests with coniferous or Broad-leaved tree, broadleaf forests that occur in the temperate zone and receive heavy rain.
Temperate rainforests occur in oceanic moist regions around the world: the Pacific temperate ...
s, coniferous forest
Conifers () are a group of cone-bearing seed plants, a subset of gymnosperms. Scientifically, they make up the division Pinophyta (), also known as Coniferophyta () or Coniferae. The division contains a single extant class, Pinopsida. All e ...
s, montane
Montane ecosystems are found on the slopes of mountains. The alpine climate in these regions strongly affects the ecosystem because temperatures lapse rate, fall as elevation increases, causing the ecosystem to stratify. This stratification is ...
riparian
A riparian zone or riparian area is the interface between land and a river or stream. In some regions, the terms riparian woodland, riparian forest, riparian buffer zone, riparian corridor, and riparian strip are used to characterize a ripar ...
zones, sagebrush
Sagebrush is the common name of several woody and herbaceous species of plants in the genus ''Artemisia (plant), Artemisia''. The best-known sagebrush is the shrub ''Artemisia tridentata''. Sagebrush is native to the western half of North Amer ...
plains, red fir
''Abies magnifica'', the red fir or silvertip fir, is a western North American fir, native to the mountains of southwest Oregon and California in the United States. It is a high-elevation tree, typically occurring at elevation, though only rarel ...
forests, semiarid sagebrush, cheatgrass
''Bromus tectorum'', known as downy brome, drooping brome, or cheatgrass, is a winter annual grass native to Europe, southwestern Asia, and northern Africa, but has become invasive in many other areas. It now is present in most of Europe, south ...
plains, and alpine meadows along the rocky shores of mountain lakes. It lives in slow-moving streams, ponds, and lakes during its aquatic breeding
Breeding is sexual reproduction that produces offspring, usually animals or plants. It can only occur between a male and a female animal or plant.
Breeding may refer to:
* Animal husbandry, through selected specimens such as dogs, horses, and rab ...
phase. The long-toed salamander hibernate
Hibernation is a state of minimal activity and metabolic reduction entered by some animal species. Hibernation is a seasonal heterothermy characterized by low body-temperature, slow breathing and heart-rate, and low metabolic rate. It is most ...
s during the cold winter months, surviving on energy reserves stored in the skin and tail.
The five subspecies
In Taxonomy (biology), biological classification, subspecies (: subspecies) is a rank below species, used for populations that live in different areas and vary in size, shape, or other physical characteristics (Morphology (biology), morpholog ...
have different genetic and ecological histories, phenotypically
In genetics, the phenotype () is the set of observable characteristics or traits of an organism. The term covers the organism's morphology (physical form and structure), its developmental processes, its biochemical and physiological properties ...
expressed in a range of color and skin patterns. Although the long-toed salamander is classified as a species of Least Concern
A least-concern species is a species that has been evaluated and categorized by the International Union for Conservation of Nature (IUCN) as not being a focus of wildlife conservation because the specific species is still plentiful in the wil ...
by the IUCN
The International Union for Conservation of Nature (IUCN) is an international organization working in the field of nature conservation and sustainable use of natural resources. Founded in 1948, IUCN has become the global authority on the status ...
, many forms of land development threaten and negatively affect the salamander's habitat.
Taxonomy
''Ambystoma macrodactylum'' is a member of the Ambystomatidae
Ambystomatidae is a family of salamanders belonging to the Suborder Salamandroidea in the class Amphibia. It contains two genera, ''Ambystoma'' (the mole salamanders) and ''Dicamptodon'' (the Pacific giant salamanders). ''Ambystoma'' contains ...
, also known as the mole salamanders. The Ambystomatidae originated approximately 81 million years ago (late Cretaceous
The Cretaceous ( ) is a geological period that lasted from about 143.1 to 66 mya (unit), million years ago (Mya). It is the third and final period of the Mesozoic Era (geology), Era, as well as the longest. At around 77.1 million years, it is the ...
) from its sister
A sister is a woman or a girl who shares parents or a parent with another individual; a female sibling. The male counterpart is a brother. Although the term typically refers to a familial relationship, it is sometimes used endearingly to ref ...
taxon Dicamptodontidae
The Pacific giant salamanders are members of the genus ''Dicamptodon''. They are large salamanders endemism, endemic to the Pacific Northwest in North America. They are included in the family Ambystomatidae, or alternatively, in their own monogen ...
. The Ambystomatidae are also members of suborder Salamandroidea
The Salamandroidea are a suborder of salamanders, referred to as advanced salamanders. The members of the suborder are found worldwide except for Antarctica, sub-Saharan Africa, and Oceania. They differ from suborder Cryptobranchoidea as the Angu ...
, which includes all the salamanders capable of internal fertilization. The sister species to ''A. macrodactylum'' is '' A. laterale'', distributed in eastern North America. However, the species-level phylogeny
A phylogenetic tree or phylogeny is a graphical representation which shows the evolutionary history between a set of species or Taxon, taxa during a specific time.Felsenstein J. (2004). ''Inferring Phylogenies'' Sinauer Associates: Sunderland, M ...
for Ambystomatidae is tentative and in need of further testing.
Systematics and biogeography
Evolutionary origins
The ancestral origins for this species stem from eastern North America
North America is a continent in the Northern Hemisphere, Northern and Western Hemisphere, Western hemispheres. North America is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South Ameri ...
, where species richness
Species richness is the number of different species represented in an community (ecology), ecological community, landscape or region. Species richness is simply a count of species, and it does not take into account the Abundance (ecology), abunda ...
of ambystomatids are highest. The following biogeographic
Biogeography is the study of the distribution of species and ecosystems in geographic space and through geological time. Organisms and biological communities often vary in a regular fashion along geographic gradients of latitude, elevation, ...
interpretation on the origins of ''A. macrodactylum'' into western North America is based on a descriptive account of fossils, genetics, and biogeography. The long-toed salamander's closest living sister species
In phylogenetics, a sister group or sister taxon, also called an adelphotaxon, comprises the closest relative(s) of another given unit in an evolutionary tree.
Definition
The expression is most easily illustrated by a cladogram:
Taxon A and ...
is '' A. laterale'', a native to northeastern North America. Ambystomatidae was isolated to the southeast of the mid-Continental or Western Interior Seaway
The Western Interior Seaway (also called the Cretaceous Seaway, the Niobraran Sea, the North American Inland Sea, or the Western Interior Sea) was a large inland sea (geology), inland sea that existed roughly over the present-day Great Plains of ...
during the Cretaceous
The Cretaceous ( ) is a geological period that lasted from about 143.1 to 66 mya (unit), million years ago (Mya). It is the third and final period of the Mesozoic Era (geology), Era, as well as the longest. At around 77.1 million years, it is the ...
(~145.5–66 Ma). While three other species of the Ambystomatidae ('' A. tigrinum'', '' A. californiense'', and '' A. gracile'') have overlapping ranges in western North America, the long-toed salamander's closest living sister species
In phylogenetics, a sister group or sister taxon, also called an adelphotaxon, comprises the closest relative(s) of another given unit in an evolutionary tree.
Definition
The expression is most easily illustrated by a cladogram:
Taxon A and ...
is '' A. laterale'', a native to northeastern North America. It has been suggested that ''A. macrodactylum'' speciated from ''A. laterale'' after the Paleocene
The Paleocene ( ), or Palaeocene, is a geological epoch (geology), epoch that lasted from about 66 to 56 mya (unit), million years ago (mya). It is the first epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), ...
(~66–55.8 Ma) with the loss of the Western Interior Seaway
The Western Interior Seaway (also called the Cretaceous Seaway, the Niobraran Sea, the North American Inland Sea, or the Western Interior Sea) was a large inland sea (geology), inland sea that existed roughly over the present-day Great Plains of ...
opening an access route for a common ancestor into the Western Cordillera. Once situated in the montane regions of western North America, species had to contend with a dynamic spatial and compositional ecology responding to the changes in altitude, as mountains grew and the climate changed. For example, the Pacific Northwest
The Pacific Northwest (PNW; ) is a geographic region in Western North America bounded by its coastal waters of the Pacific Ocean to the west and, loosely, by the Rocky Mountains to the east. Though no official boundary exists, the most common ...
became cooler in the Paleocene
The Paleocene ( ), or Palaeocene, is a geological epoch (geology), epoch that lasted from about 66 to 56 mya (unit), million years ago (mya). It is the first epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), ...
, paving the way for temperate forest
A temperate forest is a forest found between the tropical and boreal regions, located in the temperate zone. It is the second largest terrestrial biome, covering 25% of the world's forest area, only behind the boreal forest, which covers about 3 ...
to replace the warmer tropical forest
Tropical forests are forested ecoregions with tropical climates – that is, land areas approximately bounded by the Tropic of Cancer, tropics of Cancer and Tropic of Capricorn, Capricorn, but possibly affected by other factors such as prevailing ...
of the Cretaceous
The Cretaceous ( ) is a geological period that lasted from about 143.1 to 66 mya (unit), million years ago (Mya). It is the third and final period of the Mesozoic Era (geology), Era, as well as the longest. At around 77.1 million years, it is the ...
. A scenario for the splitting of ''A. macrodacylum'' and other western temperate species from their eastern counterparts involves Rocky Mountain uplift in the late Oligocene
The Oligocene ( ) is a geologic epoch (geology), epoch of the Paleogene Geologic time scale, Period that extends from about 33.9 million to 23 million years before the present ( to ). As with other older geologic periods, the rock beds that defin ...
into the Miocene
The Miocene ( ) is the first epoch (geology), geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and mea ...
. The orogeny
Orogeny () is a mountain-mountain formation, building process that takes place at a convergent boundary, convergent plate margin when plate motion compresses the margin. An or develops as the compressed plate crumples and is tectonic uplift, u ...
created a climatic barrier by removing moisture from the westerly air stream and dried the midcontinental area, from southern Alberta to the Gulf of Mexico.
Ancestors of contemporary salamanders were likely able to disperse and migrate into habitats of the Rocky Mountains
The Rocky Mountains, also known as the Rockies, are a major mountain range and the largest mountain system in North America. The Rocky Mountains stretch in great-circle distance, straight-line distance from the northernmost part of Western Can ...
and surrounding areas by the Eocene
The Eocene ( ) is a geological epoch (geology), epoch that lasted from about 56 to 33.9 million years ago (Ma). It is the second epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), Era. The name ''Eocene'' comes ...
. Mesic forests were established in western North America by the mid Eocene
The Eocene ( ) is a geological epoch (geology), epoch that lasted from about 56 to 33.9 million years ago (Ma). It is the second epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), Era. The name ''Eocene'' comes ...
and attained their contemporary range distributions by the early Pliocene
The Pliocene ( ; also Pleiocene) is the epoch (geology), epoch in the geologic time scale that extends from 5.33 to 2.58[montane
Montane ecosystems are found on the slopes of mountains. The alpine climate in these regions strongly affects the ecosystem because temperatures lapse rate, fall as elevation increases, causing the ecosystem to stratify. This stratification is ...](_blank)
environments of these time periods (Paleogene
The Paleogene Period ( ; also spelled Palaeogene or Palæogene) is a geologic period and system that spans 43 million years from the end of the Cretaceous Period Ma (million years ago) to the beginning of the Neogene Period Ma. It is the fir ...
to Neogene
The Neogene ( ,) is a geologic period and system that spans 20.45 million years from the end of the Paleogene Period million years ago ( Mya) to the beginning of the present Quaternary Period million years ago. It is the second period of th ...
) would have provided the physiographic
Physical geography (also known as physiography) is one of the three main branches of geography. Physical geography is the branch of natural science which deals with the processes and patterns in the natural environment such as the atmosphere, h ...
and ecological features supporting analogs of contemporary ''Ambystoma macrodactylum'' habitats.[Brunsfeld S, Sullivan J, Soltis D, Soltis P. (2001). Comparative phylogeography of northwestern North America: A synthesis. In: Silverton, J., Antonovics, J. (Eds.), Integrating Ecology and Evolution in a Spatial Context. The 14th Special Symposium of the British Ecological Society. British Ecological Society, Blackwell Science Ltd., Ch. 15, pp. 319–339.] The Cascade Range
The Cascade Range or Cascades is a major mountain range of western North America, extending from southern British Columbia through Washington (state), Washington and Oregon to Northern California. It includes both non-volcanic mountains, such as m ...
rose during the mid Pliocene
The Pliocene ( ; also Pleiocene) is the epoch (geology), epoch in the geologic time scale that extends from 5.33 to 2.58[rain shadow effect
A rain shadow is an area of significantly reduced rainfall behind a mountainous region, on the side facing away from prevailing winds, known as its leeward side.
Evaporated moisture from body of water, bodies of water (such as oceans and larg ...](_blank)
causing the xerification of the Columbia Basin and also altered ranges of temperate mesic ecosystems at higher elevations. The rise of the Cascades causing the xerification of the Columbia Basin is a major biogeographic feature of western North America that divided many species, including ''A. macrodactylum'', into coastal and inland lineages.
Subspecies
There are five subspecies
In Taxonomy (biology), biological classification, subspecies (: subspecies) is a rank below species, used for populations that live in different areas and vary in size, shape, or other physical characteristics (Morphology (biology), morpholog ...
of long-toed salamander. The subspecies are discerned by their geographic location and patterns in their dorsal stripe; Denzel Ferguson gives a biogeographic account of skin patterns, morphology; based on this analysis, he introduced two new subspecies: ''A. macrodactylum columbianum'' and ''A. m. sigillatum''. The ranges of subspecies are illustrated in Robert Stebbin's amphibian field guides.
Physical appearance (phenotypes)
Summary of distinguishing skin patterns and morphological features for the subspecies include:
; ''A. m. croceum'': Orange dorsal color on tail breaking into patches along black body and into tiny dots on head, often absent anterior to eyes. Sides have whitish flecks. Number of costal groove
The rib cage or thoracic cage is an endoskeletal enclosure in the thorax of most vertebrates that comprises the ribs, vertebral column and sternum, which protect the vital organs of the thoracic cavity, such as the heart, lungs and great vessels ...
s equals 13.
; ''A. m. columbianum'': Yellow to tan dorsal stripe on black body, continuous blotches to spots along body ending in narrowed blotches with spot patterns distributed on the head. White flecks along the sides and underside remaining as separate small flecks. Number of vomerine teeth
The vomer (; ) is one of the unpaired facial bones of the skull. It is located in the midsagittal line, and articulates with the sphenoid, the ethmoid, the left and right palatine bones, and the left and right maxillary bones. The vomer forms t ...
greater than 35.
; ''A. m. krausei'': Yellow to tan dorsal stripe, continuous blotches to spots along body ending in widened blotches with spot patterns distributed on the head. White flecks along the sides and underside remaining as separate small flecks. Number of vomerine teeth
The vomer (; ) is one of the unpaired facial bones of the skull. It is located in the midsagittal line, and articulates with the sphenoid, the ethmoid, the left and right palatine bones, and the left and right maxillary bones. The vomer forms t ...
equaling 32. Number of costal grooves equals 12.
; ''A. m. sigillatum'': Wax yellow to tan dorsal stripe forming spotty to irregular shaped blotches along body ending in dots or specks of dorsal color on head. Number of vomerine teeth
The vomer (; ) is one of the unpaired facial bones of the skull. It is located in the midsagittal line, and articulates with the sphenoid, the ethmoid, the left and right palatine bones, and the left and right maxillary bones. The vomer forms t ...
equals 44. Number of costal grooves equals 13.
; ''A. m. macrodactylum'': Citrine, dull citrine, to tan dorsal stripe that is diffuse and continuous along grayish body. Pattern ending in diffuse specks of stripe color or absent on head and snout. White flecks on sides sometimes coming together to form larger flecks. Number of vomerine teeth
The vomer (; ) is one of the unpaired facial bones of the skull. It is located in the midsagittal line, and articulates with the sphenoid, the ethmoid, the left and right palatine bones, and the left and right maxillary bones. The vomer forms t ...
equaling 33, forming a distinguished transverse arc. Number of costal grooves equals 13.
Biogeography and genetics
Mitochondrial DNA
Mitochondrial DNA (mtDNA and mDNA) is the DNA located in the mitochondrion, mitochondria organelles in a eukaryotic cell that converts chemical energy from food into adenosine triphosphate (ATP). Mitochondrial DNA is a small portion of the D ...
analysis identifies somewhat different ranges for the subspecies lineages. The genetic analysis, for example, identifies an additional pattern of deep divergence in the eastern part of the range. The spatial distribution of populations and genetics of this species links spatially and historically through the interconnecting mountain and temperate valley systems of western North America. The breeding fidelity of long-toed salamanders (''philopatry
Philopatry is the tendency of an organism to stay in or habitually return to a particular area. The causes of philopatry are numerous, but natal philopatry, where animals return to their birthplace to breed, may be the most common. The term derives ...
'') and other migratory behaviours reduce rates of dispersal among regions, such as within mountain basins. This aspect of their behavior restricts gene flow
In population genetics, gene flow (also known as migration and allele flow) is the transfer of genetic variation, genetic material from one population to another. If the rate of gene flow is high enough, then two populations will have equivalent ...
and increases the degree and rates of genetic differentiation. Genetic differentiation among regions is higher in the long-toed salamander than measured in most other vertebrate
Vertebrates () are animals with a vertebral column (backbone or spine), and a cranium, or skull. The vertebral column surrounds and protects the spinal cord, while the cranium protects the brain.
The vertebrates make up the subphylum Vertebra ...
groups. Natural breaks in the range of dispersal and migration
Migration, migratory, or migrate may refer to: Human migration
* Human migration, physical movement by humans from one region to another
** International migration, when peoples cross state boundaries and stay in the host state for some minimum le ...
occur where ecosystems
An ecosystem (or ecological system) is a system formed by Organism, organisms in interaction with their Biophysical environment, environment. The Biotic material, biotic and abiotic components are linked together through nutrient cycles and en ...
grade into drier xeric
Deserts and xeric shrublands are a biome defined by the World Wide Fund for Nature. Deserts and xeric (Ancient Greek 'dry') shrublands form the largest terrestrial biome, covering 19% of Earth's land surface area. Ecoregions in this habita ...
low-lands (such as prairie
Prairies are ecosystems considered part of the temperate grasslands, savannas, and shrublands biome by ecologists, based on similar temperate climates, moderate rainfall, and a composition of grasses, herbs, and shrubs, rather than trees, as the ...
climates) and at frozen or harsher terrain at high elevation extremes ().
; ''A. m. columbianum'':Genetic evidence for the 'central' subspecies (''A. m. columbianum'') suggests that it does not extend north into British Columbia, but is restricted to the Blue
Blue is one of the three primary colours in the RYB color model, RYB colour model (traditional colour theory), as well as in the RGB color model, RGB (additive) colour model. It lies between Violet (color), violet and cyan on the optical spe ...
and Wallowa Mountains
The Wallowa Mountains () are a mountain range located in the Columbia Plateau of northeastern Oregon in the United States. The range runs approximately northwest to southeast in southwestern Wallowa County and eastern Union County between the ...
of central to northeastern sections of Oregon. Populations are restricted to these areas by the Snake River Canyon (Idaho)
Snake River Canyon is a canyon formed by the Snake River in the Magic Valley region of southern Idaho, forming part of the boundary between Twin Falls County to the south and Jerome County to the north. The canyon ranges up to deep and wide, ...
to the east and low dry or xeric lands in the Madras basin to the west.
; ''A. m. macrodactylum'':The 'coastal' or 'western' subspecies (''A. m. macrodactylum'') lineage extends north from northeastern California, across the Klamath Siskiyou Range, through the Willamette Valley
The Willamette Valley ( ) is a valley in Oregon, in the Pacific Northwest region of the United States. The Willamette River flows the entire length of the valley and is surrounded by mountains on three sides: the Cascade Range to the east, the ...
, along the coastal mountain ranges, including the Cascade Mountains, and continuing north through British Columbia and up into Alaska.
; ''A. m. croceum'':The Santa Cruz long-toed salamander
The Santa Cruz long-toed salamander (''Ambystoma macrodactylum croceum'') is an endangered subspecies of the long-toed salamander, which is found only close to a few isolated ponds in Santa Cruz County, California, Santa Cruz and Monterey County ...
(''A. m. croceum'') is most closely related to the 'coastal' or 'western' subspecies. This conclusion is the most parsimonious
In philosophy, Occam's razor (also spelled Ockham's razor or Ocham's razor; ) is the problem-solving principle that recommends searching for explanations constructed with the smallest possible set of elements. It is also known as the principle o ...
biogeographic
Biogeography is the study of the distribution of species and ecosystems in geographic space and through geological time. Organisms and biological communities often vary in a regular fashion along geographic gradients of latitude, elevation, ...
explanation
An explanation is a set of statements usually constructed to describe a set of facts that clarifies the causes, context, and consequences of those facts. It may establish rules or laws, and clarifies the existing rules or laws in relation ...
with nearest populations of ''A. m. macrodactylum'' separated by approximately 300 km across the Sacramento-San Joaquin River Delta, California. The isolated endemic populations are listed as an endangered subspecies. Based on the biogeography and molecular clock calibrations, this subspecies may have been separated from the remainder of the distribution since the Miocene, molecular clock
The molecular clock is a figurative term for a technique that uses the mutation rate of biomolecules to deduce the time in prehistory when two or more life forms diverged. The biomolecular data used for such calculations are usually nucleot ...
calibrations estimating 13.9 million years of separation.
; ''A. m. krausei'':The 'eastern' subspecies (''A. m. krausei'') range is distributed throughout the interior mountains, with the western extent of its range encroaching into the low-land areas of the central interior plateau of Washington and British Columbia and the eastern extent of its range pushing through Rocky Mountain valleys into the lowland foothills and prairies of Montana and Alberta.
; ''A. m. sigillatum'':The traditional 'southern' subspecies (''A. m. sigillatum'') does not register a mitochondrial genetic identity. This subspecies was identified by Ferguson as forming an intergrade
In zoology, intergradation is the way in which two distinct subspecies are connected via areas where populations are found that have the characteristics of both. There are two types of intergradation: primary and secondary intergradation.
Primary ...
with ''A. m. columbianum'' in south central Oregon.
Thompson and Russell found another evolutionary lineage that originates in a glacially restricted area of the Salmon River Mountains, Idaho. With the arrival of the Holocene
The Holocene () is the current geologic time scale, geological epoch, beginning approximately 11,700 years ago. It follows the Last Glacial Period, which concluded with the Holocene glacial retreat. The Holocene and the preceding Pleistocene to ...
interglacial
An interglacial period (or alternatively interglacial, interglaciation) is a geological interval of warmer global average temperature lasting thousands of years that separates consecutive glacial periods within an ice age. The current Holocene i ...
, approximately 10,000 years ago, the Pleistocene glaciers receded and opened a migratory path linking these southern populations to northern areas where they currently overlap with ''A. m. krausei'' and co-migrated north into the Peace River (Canada)
The Peace River () is a river in Canada that originates in the Rocky Mountains of northern British Columbia and flows to the northeast through northern Alberta. The Peace River joins the Athabasca River in the Peace-Athabasca Delta to form the ...
Valley. Ferguson also noted an intergradation
In zoology, intergradation is the way in which two distinct subspecies are connected via areas where populations are found that have the characteristics of both. There are two types of intergradation: primary and secondary intergradation.
Primary ...
in the same geographic area, but between the morphological subspecies ''A. m. columbianum'' and ''A. m. krausei'' that run parallel to the Bitterroot
Bitterroot (''Lewisia rediviva'') is a small perennial herb in the family Montiaceae. Its specific epithet ("revived, reborn") refers to its ability to regenerate from dry and seemingly dead roots.
The genus '' Lewisia'' was moved in 2009 from ...
and Selkirk ranges. Thompson and Russell suggest that this contact zone is between two different subspecies lineages because the ''A. m. columbianum'' lineage is geographically isolated and restricted to the central Oregon Mountains.
Description
The body of the long-toed salamander is dusky black with a dorsal
Dorsal (from Latin ''dorsum'' ‘back’) may refer to:
* Dorsal (anatomy), an anatomical term of location referring to the back or upper side of an organism or parts of an organism
* Dorsal, positioned on top of an aircraft's fuselage
The fus ...
stripe of tan, yellow, or olive-green. This stripe can also be broken up into a series of spots. The sides of the body can have fine white or pale blue flecks. The belly is dark-brown or sooty in color with white flecks. Root tubercle
In anatomy, a tubercle (literally 'small tuber', Latin for 'lump') is any round nodule, small eminence, or warty outgrowth found on external or internal organs of a plant or an animal.
In plants
A tubercle is generally a wart-like projectio ...
s are present, but they are not quite as developed as other species, such as the tiger salamander
The tiger salamander (''Ambystoma tigrinum'') is a species of mole salamander and one of the largest terrestrial salamanders in North America.
Description
These salamanders usually grow to a length of with a lifespan of around 12–15 years ...
.
The egg
An egg is an organic vessel grown by an animal to carry a possibly fertilized egg cell (a zygote) and to incubate from it an embryo within the egg until the embryo has become an animal fetus that can survive on its own, at which point the ...
s of this species look similar to those of the related northwestern salamander
The northwestern salamander (''Ambystoma gracile'') is a species of mole salamander that inhabits the northwest Pacific coast of North America. These fairly large salamanders grow to 8.7 in (220 mm) in length. It is found from southeastern ...
(''A. gracile'') and tiger salamander
The tiger salamander (''Ambystoma tigrinum'') is a species of mole salamander and one of the largest terrestrial salamanders in North America.
Description
These salamanders usually grow to a length of with a lifespan of around 12–15 years ...
(''A. tigrinum''). Like many amphibians, the eggs of the long-toed salamander are surrounded by a gelatinous capsule. This capsule is transparent, making the embryo visible during development. Unlike ''A. gracile'' eggs, there are no visible signs of green algae
The green algae (: green alga) are a group of chlorophyll-containing autotrophic eukaryotes consisting of the phylum Prasinodermophyta and its unnamed sister group that contains the Chlorophyta and Charophyta/ Streptophyta. The land plants ...
, which makes egg jellies green in color. When in its egg, the long-toed salamander embryo
An embryo ( ) is the initial stage of development for a multicellular organism. In organisms that reproduce sexually, embryonic development is the part of the life cycle that begins just after fertilization of the female egg cell by the male sp ...
is darker on top and whiter below compared to a tiger salamander embryo that is light brown to grey above and cream-colored on the bottom. The eggs are about or greater in diameter with a wide outer jelly layer. Prior to hatching—both in the egg and as newborn larva
A larva (; : larvae ) is a distinct juvenile form many animals undergo before metamorphosis into their next life stage. Animals with indirect development such as insects, some arachnids, amphibians, or cnidarians typically have a larval phase ...
e—they have balancers, which are thin skin protrusions sticking out the sides and supporting the head. The balancers eventually fall off and their external gill
A gill () is a respiration organ, respiratory organ that many aquatic ecosystem, aquatic organisms use to extract dissolved oxygen from water and to excrete carbon dioxide. The gills of some species, such as hermit crabs, have adapted to allow r ...
s grow larger. Once the balancers are lost the larvae are distinguished by the sharply pointed flaring of the gills. As the larvae mature and metamorphose
Metamorphosis is a biological process by which an animal physically developmental biology, develops including birth, birth transformation or hatching, involving a conspicuous and relatively abrupt change in the animal's body structure through ...
, their limbs with digits become visible and the gills are resorbed.
The skin of a larva is mottled
Mottle is a pattern of irregular marks, spots, streaks, blotches or patches of different shades or colours. It is commonly used to describe the surface of plants or the skin of animals. In plants, mottling usually consists of yellowish spots on p ...
with black, brown, and yellow pigmentation. Skin color changes as the larvae develop and pigment cells migrate and concentrate in different regions of the body. The pigment cells, called chromatophore
Chromatophores are cells that produce color, of which many types are pigment-containing cells, or groups of cells, found in a wide range of animals including amphibians, fish, reptiles, crustaceans and cephalopod
A cephalopod is any member o ...
s, are derived from the neural crest
The neural crest is a ridge-like structure that is formed transiently between the epidermal ectoderm and neural plate during vertebrate development. Neural crest cells originate from this structure through the epithelial-mesenchymal transition, ...
. The three types of pigment chromatophores in salamanders include yellow xanthophores, black melanophores, and silvery iridiophores (or guanophores). As the larvae mature, the melanophores concentrate along the body and provide the darker background. The yellow xanthophores arrange along the spine and on top of the limbs. The rest of the body is flecked with reflective iridiophores along the sides and underneath.
As larvae metamorphose, they develop digits from their limb bud protrusions. A fully metamorphosed long-toed salamander has four digits on the front limbs and five digits on the rear limbs. Its head is longer than it is wide, and the long outer fourth toe on the hind limb of mature larvae and adults distinguishes this species from others and is also the etymological
Etymology ( ) is the study of the origin and evolution of words—including their constituent units of sound and meaning—across time. In the 21st century a subfield within linguistics, etymology has become a more rigorously scientific study. ...
origin of its specific epithet
In Taxonomy (biology), taxonomy, binomial nomenclature ("two-term naming system"), also called binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, both of which use Latin gramm ...
: ''macrodactylum'' (Greek ''makros'' = long and ''daktylos'' = toe). The adult skin has a dark brown, dark grey, to black background with a yellow, green, or dull red blotchy stripe with dots and spots along the sides. Underneath the limbs, head, and body the salamander is white, pinkish, to brown with larger flecks of white and smaller flecks of yellow. Adults are typically long.
Habitat and distribution
The long-toed salamander is an ecologically versatile species living in a variety of habitats, ranging from temperate rainforest
Temperate rainforests are rainforests with coniferous or Broad-leaved tree, broadleaf forests that occur in the temperate zone and receive heavy rain.
Temperate rainforests occur in oceanic moist regions around the world: the Pacific temperate ...
s, coniferous forests
Conifers () are a group of cone-bearing seed plants, a subset of gymnosperms. Scientifically, they make up the division Pinophyta (), also known as Coniferophyta () or Coniferae. The division contains a single extant class, Pinopsida. All e ...
, montane
Montane ecosystems are found on the slopes of mountains. The alpine climate in these regions strongly affects the ecosystem because temperatures lapse rate, fall as elevation increases, causing the ecosystem to stratify. This stratification is ...
riparian
A riparian zone or riparian area is the interface between land and a river or stream. In some regions, the terms riparian woodland, riparian forest, riparian buffer zone, riparian corridor, and riparian strip are used to characterize a ripar ...
, sagebrush
Sagebrush is the common name of several woody and herbaceous species of plants in the genus ''Artemisia (plant), Artemisia''. The best-known sagebrush is the shrub ''Artemisia tridentata''. Sagebrush is native to the western half of North Amer ...
plains, red fir
''Abies magnifica'', the red fir or silvertip fir, is a western North American fir, native to the mountains of southwest Oregon and California in the United States. It is a high-elevation tree, typically occurring at elevation, though only rarel ...
forest, semiarid sagebrush, cheatgrass
''Bromus tectorum'', known as downy brome, drooping brome, or cheatgrass, is a winter annual grass native to Europe, southwestern Asia, and northern Africa, but has become invasive in many other areas. It now is present in most of Europe, south ...
plains, to alpine meadow
Alpine tundra is a type of natural region or biome that does not contain trees because it is at high elevation, with an associated harsh climate. As the latitude of a location approaches the poles, the threshold elevation for alpine tundra gets ...
s along the rocky shores of mountain lakes. Adults can be located in forested understory
In forestry and ecology, understory (American English), or understorey (English in the Commonwealth of Nations, Commonwealth English), also known as underbrush or undergrowth, includes plant life growing beneath the Canopy (biology), forest ca ...
, hiding under coarse woody debris
Coarse woody debris (CWD) or coarse woody habitat (CWH) refers to fallen dead trees and the remains of large branches on the ground in forests and in rivers or wetlands.Keddy, P.A. 2010. Wetland Ecology: Principles and Conservation (2nd edition). C ...
, rocks, and in small mammal burrows. During the spring breeding season, adults can be found under debris or in the shoreline shallows of rivers, streams, lakes, and ponds. Ephemeral waters are often frequented.
This species
A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...
is one of the most widely distributed salamander
Salamanders are a group of amphibians typically characterized by their lizard-like appearance, with slender bodies, blunt snouts, short limbs projecting at right angles to the body, and the presence of a tail in both larvae and adults. All t ...
s in North America, second only to the tiger salamander
The tiger salamander (''Ambystoma tigrinum'') is a species of mole salamander and one of the largest terrestrial salamanders in North America.
Description
These salamanders usually grow to a length of with a lifespan of around 12–15 years ...
. Its altitudinal range runs from sea level up to , spanning a wide variety of vegetational zones. The range includes isolated endemic
Endemism is the state of a species being found only in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also foun ...
populations in Monterey Bay
Monterey Bay is a bay of the Pacific Ocean located on the coast of the U.S. state of California, south of the San Francisco Bay Area. San Francisco itself is further north along the coast, by about 75 miles (120 km), accessible via California S ...
and Santa Cruz, California
Santa Cruz (Spanish language, Spanish for "Holy Cross") is the largest city and the county seat of Santa Cruz County, California, Santa Cruz County, in Northern California. As of the 2020 United States census, 2020 census, the city population ...
. The distribution reconnects in northeastern Sierra Nevada
The Sierra Nevada ( ) is a mountain range in the Western United States, between the Central Valley of California and the Great Basin. The vast majority of the range lies in the state of California, although the Carson Range spur lies primari ...
running continuously along the Pacific Coast
Pacific coast may be used to reference any coastline that borders the Pacific Ocean.
Geography Americas North America
Countries on the western side of North America have a Pacific coast as their western or south-western border. One of th ...
to Juneau, Alaska
Juneau ( ; ), officially the City and Borough of Juneau, is the List of capitals in the United States, capital of the U.S. state of Alaska, located along the Gastineau Channel and the Southeast Alaska, Alaskan panhandle. Juneau was named the ...
, with populations dotted along the Taku and Stikine River
The Stikine River ( ) is a major river in northern British Columbia (BC), Canada and southeastern Alaska in the United States. It drains a large, remote upland area known as the Stikine Country east of the Coast Mountains. Flowing west and ...
valleys. From the Pacific coast, the range extends longitudinally to the eastern foothills of the Rocky Mountains
The Rocky Mountains, also known as the Rockies, are a major mountain range and the largest mountain system in North America. The Rocky Mountains stretch in great-circle distance, straight-line distance from the northernmost part of Western Can ...
in Montana
Montana ( ) is a landlocked U.S. state, state in the Mountain states, Mountain West subregion of the Western United States. It is bordered by Idaho to the west, North Dakota to the east, South Dakota to the southeast, Wyoming to the south, an ...
and Alberta
Alberta is a Provinces and territories of Canada, province in Canada. It is a part of Western Canada and is one of the three Canadian Prairies, prairie provinces. Alberta is bordered by British Columbia to its west, Saskatchewan to its east, t ...
.
Ecology and life cycle
Eggs
Like all amphibians, the life of a long-toed salamander begins as an egg. In the northern extent of its range, the eggs are laid in lumpy masses along grass, sticks, rocks, or the mucky substrate
Substrate may refer to:
Physical layers
*Substrate (biology), the natural environment in which an organism lives, or the surface or medium on which an organism grows or is attached
** Substrate (aquatic environment), the earthy material that exi ...
of a calm pond.[Green DM, Campbell RW. (1992). ''The Amphibians of British Columbia.'' Royal British Columbia Museum Handbook No. 45. Province of British Columbia, Ministry of Tourism and Ministry Responsible for Culture.] The number of eggs in a single mass ranges in size, possibly up to 110 eggs per cluster. Females invest a significant amount of resources into egg production, with the ovaries accounting for over 50% of the body mass in the pre-breeding season. A maximum of 264 eggs have been found in a single female—a large number considering each egg is approximately in diameter. The egg mass is held together by a gelatinous
Gelatin or gelatine () is a translucent, colorless, flavorless food ingredient, commonly derived from collagen taken from animal body parts. It is brittle when dry and rubbery when moist. It may also be referred to as hydrolysis, hydrolyzed col ...
outer layer protecting the outer capsule of individual eggs. The eggs are sometimes laid singly, especially in warmer climates south of the Canada and US border. The egg jellies contribute a yearly supply of biological material that supports the chemistry and nutrient dynamics of shallow-water aquatic ecosystem
An aquatic ecosystem is an ecosystem found in and around a body of water, in contrast to land-based terrestrial ecosystems. Aquatic ecosystems contain communities of organisms—aquatic life—that are dependent on each other and on their environ ...
s and adjacent forest ecosystem
Forest ecology is the scientific study of the interrelated patterns, processes, flora, fauna, funga, and ecosystems in forests. The management of forests is known as forestry, silviculture, and forest management. A forest ecosystem is a natural wo ...
s. The eggs also provide habitat for water molds, also known as oomycetes
The Oomycetes (), or Oomycota, form a distinct phylogenetic lineage of fungus-like eukaryotic microorganisms within the Stramenopiles. They are filamentous and heterotrophic, and can reproduce both sexually and asexually. Sexual reproduction o ...
.
Larvae
Larva
A larva (; : larvae ) is a distinct juvenile form many animals undergo before metamorphosis into their next life stage. Animals with indirect development such as insects, some arachnids, amphibians, or cnidarians typically have a larval phase ...
e hatch from their egg casing in two to six weeks. They are born carnivore
A carnivore , or meat-eater (Latin, ''caro'', genitive ''carnis'', meaning meat or "flesh" and ''vorare'' meaning "to devour"), is an animal or plant
Plants are the eukaryotes that form the Kingdom (biology), kingdom Plantae; they ar ...
s, feeding instinct
Instinct is the inherent inclination of a living organism towards a particular complex behaviour, containing innate (inborn) elements. The simplest example of an instinctive behaviour is a fixed action pattern (FAP), in which a very short to me ...
ively on small invertebrate
Invertebrates are animals that neither develop nor retain a vertebral column (commonly known as a ''spine'' or ''backbone''), which evolved from the notochord. It is a paraphyletic grouping including all animals excluding the chordata, chordate s ...
s that move in their field of vision
The visual field is "that portion of space in which objects are visible at the same moment during steady fixation of the gaze in one direction"; in ophthalmology and neurology the emphasis is mostly on the structure inside the visual field and it i ...
. Food items include small aquatic crustacean
Crustaceans (from Latin meaning: "those with shells" or "crusted ones") are invertebrate animals that constitute one group of arthropods that are traditionally a part of the subphylum Crustacea (), a large, diverse group of mainly aquatic arthrop ...
s (cladocera
The Diplostraca or Cladocera, commonly known as water fleas, is a superorder (biology), superorder of small, mostly freshwater crustaceans, most of which feed on microscopic chunks of organic matter, though some forms are predatory.
Over 1000 sp ...
ns, copepod
Copepods (; meaning 'oar-feet') are a group of small crustaceans found in nearly every freshwater and saltwater habitat (ecology), habitat. Some species are planktonic (living in the water column), some are benthos, benthic (living on the sedimen ...
s and ostracod
Ostracods, or ostracodes, are a Class (biology), class of the crustacean, Crustacea (class Ostracoda), sometimes known as seed shrimp. Some 33,000 species (only 13,000 of which are extant taxon, extant) have been identified,Brandão, S.N.; Antoni ...
s), aquatic diptera
Flies are insects of the order Diptera, the name being derived from the Greek δι- ''di-'' "two", and πτερόν ''pteron'' "wing". Insects of this order use only a single pair of wings to fly, the hindwings having evolved into advance ...
ns and tadpole
A tadpole or polliwog (also spelled pollywog) is the Larva, larval stage in the biological life cycle of an amphibian. Most tadpoles are fully Aquatic animal, aquatic, though some species of amphibians have tadpoles that are terrestrial animal, ...
s. As they develop, they naturally feed upon larger prey
Predation is a biological interaction in which one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes parasitism and micropredation (which usually do not ki ...
. To increase their chances for survival, some individuals grow bigger heads and become cannibals
Cannibalism is the act of consuming another individual of the same species as food. Cannibalism is a common ecological interaction in the animal kingdom and has been recorded in more than 1,500 species. Human cannibalism is also well documente ...
, and feed upon their own brood mates.
Metamorphosis and juveniles
After the larvae grow and mature, for at least one season (the larval period lasts about four months on the Pacific coast
Pacific coast may be used to reference any coastline that borders the Pacific Ocean.
Geography Americas North America
Countries on the western side of North America have a Pacific coast as their western or south-western border. One of th ...
), they absorb their gills and metamorphose
Metamorphosis is a biological process by which an animal physically developmental biology, develops including birth, birth transformation or hatching, involving a conspicuous and relatively abrupt change in the animal's body structure through ...
into terrestrial juveniles that roam the forest undergrowth
In forestry and ecology, understory (American English), or understorey (Commonwealth English), also known as underbrush or undergrowth, includes plant life growing beneath the forest canopy without penetrating it to any great extent, but above ...
. Metamorphosis has been reported as early as July at sea level, for ''A. m. croceum'' in October to November and even January. At higher elevations the larvae may overwinter
Overwintering is the process by which some organisms pass through or wait out the winter season, or pass through that period of the year when "winter" conditions (cold or sub-zero temperatures, ice, snow, limited food supplies) make normal activ ...
, develop, and grow for an extra season before metamorphosing. In lakes at higher elevations, the larvae can reach sizes of snout to vent length (SVL) at metamorphosis, but at lower elevations they develop faster and metamorphose when they reach SVL.
Adults
As adults, long-toed salamanders often go unnoticed because they live a subterranean lifestyle digging, migrating, and feeding on the invertebrates in forest soils, decaying logs, small rodent
Rodents (from Latin , 'to gnaw') are mammals of the Order (biology), order Rodentia ( ), which are characterized by a single pair of continuously growing incisors in each of the upper and Mandible, lower jaws. About 40% of all mammal specie ...
burrow
file:Chipmunk-burrow (exits).jpg, An eastern chipmunk at the entrance of its burrow
A burrow is a hole or tunnel excavated into the ground by an animal to construct a space suitable for habitation or temporary refuge, or as a byproduct of Animal lo ...
s or rock fissure
A fissure is a long, narrow crack opening along the surface of Earth. The term is derived from the Latin word , which means 'cleft' or 'crack'. Fissures emerge in Earth's crust, on ice sheets and glaciers, and on volcanoes.
Ground fissure
A ...
s. The adult diet consists of insects, tadpoles, worms, beetles and small fish. Salamanders are preyed upon by garter snakes, small mammals, birds, and fish. An adult may live 6–10 years, with the largest individuals weighing approximately , snout to vent lengths reaching , and total lengths reaching .
Behaviour
Seasonal
The life history of the long-toed salamander varies greatly with elevation and climate. Seasonal dates of migration to and from the breeding ponds can be correlated
In statistics, correlation or dependence is any statistical relationship, whether causal or not, between two random variables or bivariate data. Although in the broadest sense, "correlation" may indicate any type of association, in statistic ...
with bouts of sustained rainfall, ice thaw, or snow melt sufficient to replenish the (often) seasonal ponds. Eggs may be spawned at low elevations as early as mid-February in southern Oregon
Oregon ( , ) is a U.S. state, state in the Pacific Northwest region of the United States. It is a part of the Western U.S., with the Columbia River delineating much of Oregon's northern boundary with Washington (state), Washington, while t ...
, from early January to July in northwestern Washington
Washington most commonly refers to:
* George Washington (1732–1799), the first president of the United States
* Washington (state), a state in the Pacific Northwest of the United States
* Washington, D.C., the capital of the United States
** A ...
, from January to March in southeastern Washington, and from mid-April to early May in Waterton Lakes National Park
Waterton Lakes National Park is in the southwest corner of Alberta, Canada. The national park borders Glacier National Park in Montana, United States. Waterton was the fourth Canadian national park, formed in 1895 as Kootenay Lakes Forest Reserve ...
, Alberta. The timing of breeding can be highly variable; of notable mention, several egg masses in early stages of development were found on July 8, 1999 along the British Columbia
British Columbia is the westernmost Provinces and territories of Canada, province of Canada. Situated in the Pacific Northwest between the Pacific Ocean and the Rocky Mountains, the province has a diverse geography, with rugged landscapes that ...
provincial border outside Jasper, Alberta
Jasper is a specialized municipality and townsite in western Alberta within the Canadian Rockies. The townsite is in the Athabasca River valley and is the commercial centre of Jasper National Park.
History
Established in 1813, Jasper ...
. Adults migrate seasonally to return to their natal
NATAL or Natal may refer to:
Places
* Natal, Rio Grande do Norte, a city in Brazil
* Natal, South Africa (disambiguation), a region in South Africa
** Natalia Republic, a former country (1839–1843)
** Colony of Natal, a former British colony ( ...
breeding ponds, with males arriving earlier and staying longer than females, and some individuals have been seen migrating along snow banks on warm spring days. Gender differences (or sexual dimorphism
Sexual dimorphism is the condition where sexes of the same species exhibit different Morphology (biology), morphological characteristics, including characteristics not directly involved in reproduction. The condition occurs in most dioecy, di ...
) in this species are only apparent during the breeding season, when mature males display an enlarged or bulbous vent area.
Breeding
The time of breeding depends on the elevation and latitude of the salamander's habitat. Generally, the lower-elevation salamanders breed in the fall, winter, and early spring. Higher-elevation salamanders breed in spring and early summer. In the higher climates especially, salamanders will enter ponds and lakes that still have ice floating.[
Adults aggregate in large numbers (>20 individuals) under rocks and logs along the immediate edge of the breeding sites and breed explosively over a few days.] Suitable breeding sites include small fish-free ponds, marshes, shallow lakes and other still-water wetlands. Like other ambystomatid salamanders, they have evolved a characteristic courtship dance
A courtship display is a set of display behaviors in which an animal, usually a male, attempts to attract a mate; the mate Mate choice, exercises choice, so sexual selection acts on the display. These behaviors often include ritualized movement ( ...
where they rub bodies and release pheromones
A pheromone () is a secreted or excreted chemical factor that triggers a social response in members of the same species. Pheromones are chemicals capable of acting like hormones outside the body of the secreting individual, to affect the behavi ...
from their chin gland prior to assuming a copulatory mating
In biology, mating is the pairing of either opposite-sex or hermaphroditic organisms for the purposes of sexual reproduction. ''Fertilization'' is the fusion of two gametes. '' Copulation'' is the union of the sex organs of two sexually repr ...
position. Once in position, the male deposits a spermatophore
A spermatophore, from Ancient Greek σπέρμα (''spérma''), meaning "seed", and -φόρος (''-phóros''), meaning "bearing", or sperm ampulla is a capsule or mass containing spermatozoa created by males of various animal species, especiall ...
, which is a gooey stalk tipped with a packet of sperm, and walks the female forward to be inseminate
Insemination is the introduction of spermatozoon, sperm (in semen) into a female or hermaphrodite's reproductive system in order to Fertilization, fertilize the ovum through sexual reproduction. The sperm enters into the uterus of a mammal or the ...
d. Males may mate more than once and may deposit as many as 15 spermatophores over the course of a five-hour period. The courtship dance for the long-toed salamander is similar to other species of ''Ambystoma'' and very similar to '' A. jeffersonianum''. In the long-toed salamander, there is no rubbing or head-butting; the males directly approach females and grab on, while the females try to rapidly swim away. The males clasp the female from behind the forelimbs and shake, a behavior called amplexus
Amplexus (Latin "embrace") is a type of Mating, mating behavior exhibited by some External fertilization, externally fertilizing species (chiefly amphibians, Amphipoda, amphipods, and horseshoe crabs) in which a male grasps a female with his fro ...
. Males sometimes clasp other amphibian species during breeding and shake them as well. The male only grabs with the front limbs and never uses his hind limbs during the courtship dance as he rubs his chin side to side pressing down on the female's head. The female struggles but later becomes subdued. Males increase the tempo and motions, rubbing over the female's nostrils, sides, and sometimes the vent. When the female becomes quite docile the male moves forward with his tail positioned over her head, raised, and waving at the tip. If the female accepts the males courtship, the male directs her snout toward his vent region while both move forward stiffly with pelvic undulations. As the female follows, the male stops and deposits a spermatophore, and the female will move forward with the male to raise her tail and receive the sperm packet. The full courtship dance is rarely accomplished in the first attempt. Females deposit their eggs a few days after mating.
Energy storage and defense mechanisms
In some lowland areas the adult salamanders will remain active all winter long, excluding cold spells. However, during the cold winter months in the northern parts of its range, the long-toed salamander burrows below the frost-line in a coarse substrate to hibernate
Hibernation is a state of minimal activity and metabolic reduction entered by some animal species. Hibernation is a seasonal heterothermy characterized by low body-temperature, slow breathing and heart-rate, and low metabolic rate. It is most ...
in clusters of 8–14 individuals. While hibernating, it survives on protein energy reserves that are stored in its skin and along its tail. These proteins serve a secondary function as part of a mixture or concoction of skin secretions that is used for defense. When threatened, the long-toed salamander will wave its tail and secrete an adhesive white milky substance that is noxious and likely poisonous. The color of its skin can serve as a warning to predators (''aposematism
Aposematism is the Advertising in biology, advertising by an animal, whether terrestrial or marine, to potential predation, predators that it is not worth attacking or eating. This unprofitability may consist of any defenses which make the pr ...
'') that it will taste bad. Its skin colors and patterns are diverse, ranging from a dark black to reddish brown background that is spotted or blotched by a pale-reddish-brown, pale-green, to a bright yellow stripe. An adult may also drop part of its tail and slink away while the tail bit acts as a squirmy decoy; this is called ''autotomy
Autotomy (from the Greek ''auto-'', "self-" and ''tome'', "severing", αὐτοτομία) or 'self-amputation', is the behaviour whereby an animal sheds or discards an appendage, usually as a self-defense mechanism to elude a predator's grasp ...
''. The regeneration
Regeneration may refer to:
Science and technology
* Regeneration (biology), the ability to recreate lost or damaged cells, tissues, organs and limbs
* Regeneration (ecology), the ability of ecosystems to regenerate biomass, using photosynthesis
...
and regrowth of the tail is one example of the developmental
Development of the human body is the process of growth to maturity. The process begins with fertilization, where an egg released from the ovary of a female is penetrated by a sperm cell from a male. The resulting zygote develops through mitosis ...
physiology
Physiology (; ) is the science, scientific study of function (biology), functions and mechanism (biology), mechanisms in a life, living system. As a branches of science, subdiscipline of biology, physiology focuses on how organisms, organ syst ...
of amphibians that is of great interest to the medical profession.
Conservation status
While the long-toed salamander is classified as least concern by the IUCN
The International Union for Conservation of Nature (IUCN) is an international organization working in the field of nature conservation and sustainable use of natural resources. Founded in 1948, IUCN has become the global authority on the status ...
, many forms of land development negatively affect the salamander's habitat and have put new perspectives and priorities into its conservation biology
Conservation biology is the study of the conservation of nature and of Earth's biodiversity with the aim of protecting species, their habitats, and ecosystems from excessive rates of extinction and the erosion of biotic interactions. It is an i ...
. Conservation priorities focus at the population level of diversity, which is declining at rates ten times that of species extinction. Population level diversity is what provides ecosystem services
Ecosystem services are the various benefits that humans derive from Ecosystem, ecosystems. The interconnected Biotic_material, living and Abiotic, non-living components of the natural environment offer benefits such as pollination of crops, clean ...
, such as the keystone role that salamanders play in the soil ecosystems, including the nutrient cycling
A nutrient cycle (or ecological recycling) is the movement and exchange of inorganic and organic matter back into the production of matter. Energy flow is a unidirectional and noncyclic pathway, whereas the movement of mineral nutrients is cyc ...
that supports wetland and forested ecosystems.
Two life-history features of amphibians are often cited as a reason why amphibians are good indicators of environmental health or 'canaries in the coal mine'. Like all amphibians, the long-toed salamander has both an aquatic and terrestrial life transition and semipermeable skin. Since they serve different ecological functions in the water than they do in land, the loss of one amphibian species is equivalent to the loss of two ecological species. The second notion is that amphibians, such as long-toed salamanders, are more susceptible to the absorption of pollutants because they naturally absorb water and oxygen through their skin. The validity of this special sensitivity to environmental pollutants, however, has been called into question. The problem is more complex, because not all amphibians are equally susceptible to environmental damage because there is such a diverse array of life histories among species.
Long-toed salamander populations are threatened by fragmentation, introduced species
An introduced species, alien species, exotic species, adventive species, immigrant species, foreign species, non-indigenous species, or non-native species is a species living outside its native distributional range, but which has arrived ther ...
, and UV radiation
Ultraviolet radiation, also known as simply UV, is electromagnetic radiation of wavelengths of 10–400 nanometers, shorter than that of visible light, but longer than X-rays. UV radiation is present in sunlight and constitutes about 10% of t ...
. Forestry, roads, and other land developments have altered the environments that amphibians migrate to, and have increased mortality. Places such as Waterton Lakes National Park
Waterton Lakes National Park is in the southwest corner of Alberta, Canada. The national park borders Glacier National Park in Montana, United States. Waterton was the fourth Canadian national park, formed in 1895 as Kootenay Lakes Forest Reserve ...
have installed a road tunnel underpass to allow safe passage and to sustain the migration ecology of the specie
The distribution of the long-toed salamander overlaps extensively with the forestry industry, a dominant resource supporting the economy of British Columbia and the western United States. Long-toed salamanders will alter migration
Migration, migratory, or migrate may refer to: Human migration
* Human migration, physical movement by humans from one region to another
** International migration, when peoples cross state boundaries and stay in the host state for some minimum le ...
behaviour and are affected negatively by forestry practices not offering sizable Riparian buffer, management buffers and protections for the smaller wetlands where salamanders breed. Populations near the Peace River Valley, Alberta, have been lost to the clearing and draining of wetlands for agriculture. Trout
Trout (: trout) is a generic common name for numerous species of carnivorous freshwater ray-finned fishes belonging to the genera '' Oncorhynchus'', ''Salmo'' and ''Salvelinus'', all of which are members of the subfamily Salmoninae in the ...
introduced for the sport fisheries into once fishless lakes are also destroying long-toed salamander populations. Introduced goldfish prey on the eggs and larvae of long-toed salamanders. Increased exposure to UVB
Ultraviolet radiation, also known as simply UV, is electromagnetic radiation of wavelengths of 10–400 nanometers, shorter than that of visible light, but longer than X-rays. UV radiation is present in sunlight and constitutes about 10% of the ...
radiation is another factor being implicated in the global decline of amphibians and the long-toed salamander is also susceptible to this threat, which increases the incidence of deformities and reduces their survival and growth rates.
The subspecies ''Ambystoma macrodactylum croceum'' (Santa Cruz Long-toed Salamander
The Santa Cruz long-toed salamander (''Ambystoma macrodactylum croceum'') is an endangered subspecies of the long-toed salamander, which is found only close to a few isolated ponds in Santa Cruz County, California, Santa Cruz and Monterey County ...
) is of particular concern and it was afforded protections in 1967 under the US Endangered Species Act
The Endangered Species Act of 1973 (ESA; 16 U.S.C. § 1531 et seq.) is the primary law in the United States for protecting and conserving imperiled species. Designed to protect critically imperiled species from extinction as a "consequence of e ...
. This subspecies lives in a narrow range of habitat in Santa Cruz County and Monterey County
Monterey County ( ), officially the County of Monterey, is a county located on the Pacific coast in the U.S. state of California. As of the 2020 United States census, its population was 439,035. The county's largest city and county seat is ...
, California. Prior to receiving protections, some few remaining populations were threatened by development. The subspecies is ecologically
Ecology () is the natural science of the relationships among living organisms and their environment. Ecology considers organisms at the individual, population, community, ecosystem, and biosphere levels. Ecology overlaps with the closely re ...
unique, having unique and irregular skin patterns on its back, a unique moisture tolerance, and it is also an endemic
Endemism is the state of a species being found only in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also foun ...
that is geographically isolated from the rest of the species range. Other subspecies include ''A. m. columbianum'', ''A. m. krausei'', ''A. m. macrodactylum'' and ''A. m. sigillatum''.
See also
* Santa Cruz long-toed salamander
The Santa Cruz long-toed salamander (''Ambystoma macrodactylum croceum'') is an endangered subspecies of the long-toed salamander, which is found only close to a few isolated ponds in Santa Cruz County, California, Santa Cruz and Monterey County ...
, an endangered subspecies
References
External links
{{Authority control
Mole salamanders
Amphibians of Canada
Amphibians of the United States
Taxa named by Spencer Fullerton Baird
Amphibians described in 1850