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Gasterosteus Doryssus
''Gasterosteus doryssus'' is an extinct species of freshwater stickleback fish that inhabited inland freshwater habitats of the North American Great Basin during the Miocene. It is known from thousands of articulated fossil skeletons, comprising various age classes and two different ecomorphs, discovered in diatomite deposits of the Truckee Formation near Hazen, Nevada. ''G. doryssus'' inhabited Lake Truckee, a predecessor to Lake Lahontan. Lake Truckee was subject to seasonal diatom blooms that would settle to the lake bottom to form diatomite, fossilizing any other animals that died during the season. This seasonal diatomite deposition provides an exquisite record of the annual dynamics of this ecosystem over several millennia, including a time series of the evolution of ''G. doryssus'' over 100,000 years and the eco-evolutionary dynamics that drove it. The time series of ''G. doryssus'' fossils has been used to provide evidence for and against specific evolutionary models, ...
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Late Miocene
The Late Miocene (also known as Upper Miocene) is a sub-epoch of the Miocene epoch (geology), Epoch made up of two faunal stage, stages. The Tortonian and Messinian stages comprise the Late Miocene sub-epoch, which lasted from 11.63 Ma (million years ago) to 5.333 Ma. The evolution of ''Homo'' The gibbons (family Hylobatidae) and orangutans (genus ''Pongo'') were the first groups to split from the line leading to the hominins, including humans, then gorillas (genus ''Gorilla''), and finally chimpanzees and bonobos (genus ''Pan (genus), Pan''). The splitting date between hominin and chimpanzee lineages is placed by some between 4 and 8 million years ago, that is, during the Late Miocene. References External links GeoWhen Database - Late Miocene
Miocene, .03 Miocene geochronology, 03 Messinian, * Tortonian, * {{geochronology-stub ...
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Three-spined Stickleback
The three-spined stickleback (''Gasterosteus aculeatus'') is a fish native to most inland and coastal waters north of 30°N. It has long been a subject of scientific study for many reasons. It shows great morphological variation throughout its range, ideal for questions about evolution and population genetics. Many populations are anadromous (they live in seawater but breed in fresh or brackish water) and very tolerant of changes in salinity, a subject of interest to physiologists. It displays elaborate breeding behavior (defending a territory, building a nest, taking care of the eggs and fry) and it can be social (living in shoals outside the breeding season) making it a popular subject of inquiry in fish ethology and behavioral ecology. Its antipredator adaptations, host-parasite interactions, sensory physiology, reproductive physiology, and endocrinology have also been much studied. Facilitating these studies is the fact that the three-spined stickleback is easy to find in nat ...
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Monotypic Taxon
In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of Genus, genera, the term "unispecific" or "monospecific" is sometimes preferred. In botanical nomenclature, a monotypic genus is a genus in the special case where a genus and a single species are simultaneously described. Theoretical implications Monotypic taxa present several important theoretical challenges in biological classification. One key issue is known as "Gregg's Paradox": if a single species is the only member of multiple hierarchical levels (for example, being the only species in its genus, which is the only genus in its family), then each level needs a distinct definition to maintain logical structure. Otherwise, the different taxonomic ranks become effectively identical, which creates problems for organizing biological diversity in a hierarchical o ...
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Punctuated Equilibrium
In evolutionary biology, punctuated equilibrium (also called punctuated equilibria) is a Scientific theory, theory that proposes that once a species appears in the fossil record, the population will become stable, showing little evolution, evolutionary change for most of its geological history. : ''Reprinted in'' * * This state of little or no morphological change is called ''stasis''. When significant evolutionary change occurs, the theory proposes that it is generally restricted to rare and geologic time scale, geologically rapid events of branching speciation called cladogenesis. Cladogenesis is the process by which a species splits into two distinct species, rather than one species gradually transforming into another. Punctuated equilibrium is commonly contrasted with phyletic gradualism, the idea that evolution generally occurs uniformly by the steady and gradual transformation of whole lineages (anagenesis). In 1972, paleontologists Niles Eldredge and Stephen Jay Goul ...
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Gradual Evolution
Anagenesis is the gradual evolution of a species that continues to exist as an interbreeding population. This contrasts with cladogenesis, which occurs when branching or splitting occurs, leading to two or more lineages and resulting in separate species. Anagenesis does not always lead to the formation of a new species from an ancestral species. When speciation does occur as different lineages branch off and cease to interbreed, a core group may continue to be defined as the original species. The evolution of this group, without extinction or species selection, is anagenesis. Hypotheses One hypothesis is that during the speciation event in anagenetic evolution, the original populations increases quickly, and then racks up genetic variation over long periods of time by mutation and recombination in a stable environment. Other factors, such as selection or genetic drift will have such a significant effect on genetic material and physical traits that a species can be acknowledged ...
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Biological Invasion
An invasive species is an introduced species that harms its new environment. Invasive species adversely affect habitats and bioregions, causing Ecology, ecological, Natural environment, environmental, and/or Economy, economic damage. The term can also be used for native species that become harmful to their native environment after human alterations to its food web. Since the 20th century, invasive species have become serious economic, social, and environmental threats worldwide. Invasion of long-established ecosystems by organisms is a natural phenomenon, but human-facilitated introductions have greatly increased the rate, scale, and geographic range of invasion. For millennia, Human, humans have served as both accidental and deliberate dispersal agents, beginning with their early human migrations, earliest migrations, accelerating in the Age of Discovery, and accelerating again with the spread of international trade. Notable invasive plant species include the kudzu vine, Her ...
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Fundulus Nevadensis
''Fundulus'' is a genus of ray-finned fishes in the superfamily Funduloidea, family Fundulidae (of which it is the type genus). It belongs to the order of toothcarps (Cyprinodontiformes), and therein the large suborder Cyprinodontoidei. Most of its closest living relatives are egg-laying, with the notable exception of the splitfin livebearers (Goodeidae). They are usually smallish; most species reaching a length of at most 4 in (10 cm) when fully grown. However, a few larger species exist, with the giant killifish ('' F. grandissimus'') and the northern studfish ('' F. catenatus'') growing to twice the genus' average size. Many of the 40-odd species are commonly known by the highly ambiguous name "killifish" (the general term for egg-laying toothcarps), or the somewhat less ambiguous " topminnow" (a catch-all term for Fundulidae). "Studfish" is a quite unequivocal vernacular name applied to some other ''Fundulus'' species; it is not usually used to refer to the genus as a ...
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Killifish
A killifish is any of various oviparous (egg-laying) cyprinodontiform fish, including families Aplocheilidae, Pantanodontidae, Cyprinodontidae, Fundulidae, Nothobranchiidae, Profundulidae, Aphaniidae and Valenciidae. All together, there are 1,270 species of killifish, the biggest family being Rivulidae, containing more than 320 species. As an adaptation to living in ephemeral waters, the eggs of most killifish can survive periods of partial dehydration. Many of the species rely on such a diapause, since the eggs would not survive more than a few weeks if entirely submerged in water. The adults of some species, such as ''Kryptolebias marmoratus'', can additionally survive out of the water for several weeks. Most killifish are small, measuring from , with the largest species growing to just under . The word ''killifish'' is of uncertain origin, but is likely to have come from the Dutch ''kil'' for a kill (small stream). Although killifish is sometimes used as an English eq ...
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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 include rocky coastlines, sandy beaches, forests, lakes, mountains, inland deserts and grassy plains. British Columbia borders the province of Alberta to the east; the territories of Yukon and Northwest Territories to the north; the U.S. states of Washington (state), Washington, Idaho and Montana to the south, and Alaska to the northwest. With an estimated population of over 5.7million as of 2025, it is Canada's Population of Canada by province and territory, third-most populous province. The capital of British Columbia is Victoria, British Columbia, Victoria, while the province's largest city is Vancouver. Vancouver and its suburbs together make up List of census metropolitan areas and agglomerations in Canada, the third-largest metropolit ...
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Planktivore
A planktivore is an aquatic organism that feeds on planktonic food, including zooplankton and phytoplankton. Planktivorous organisms encompass a range of some of the planet's smallest to largest multicellular animals in both the present day and in the past billion years; basking sharks and copepods are just two examples of giant and microscopic organisms that feed upon plankton. Planktivory can be an important mechanism of top-down control that contributes to trophic cascades in aquatic and marine systems. There is a tremendous diversity of feeding strategies and behaviors that planktivores utilize to capture prey. Some planktivores utilize tides and currents to migrate between estuaries and coastal waters; other aquatic planktivores reside in lakes or reservoirs where diverse assemblages of plankton are present, or migrate vertically in the water column searching for prey. Planktivore populations can impact the abundance and community composition of planktonic species through th ...
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Limnetic Zone
The limnetic zone is the open and well-lit area of a freestanding body of fresh water, such as a lake or pond. Not included in this area is the littoral zone, which is the shallow, near-shore area of the water body. The key difference between the littoral zone and the limnetic zone is the presence of rooted plant growth. The floor under the limnetic zone cannot sustain plant growth due to a lack of sunlight for photosynthesis. In extremely shallow bodies of water, light may penetrate all the way to floor even in the deepest center parts of the lake. In this situation, there is an absence of a limnetic zone and the littoral zone spans the entire lake. Together, these two zones comprise the photic zone. There are two main sources of oxygen to the photic zone: atmospheric mixing and photosynthesis. Oxygen is dissolved when air interacts with water on the surface, and is increased with wave and wind action. Unlike the profundal zone, the limnetic zone is the layer that receives suf ...
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