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Evidence For Speciation By Reinforcement
Reinforcement is a process within speciation where natural selection increases the reproductive isolation between two populations of species by reducing the production of hybrids. Evidence for speciation by reinforcement has been gathered since the 1990s, and along with data from comparative studies and laboratory experiments, has overcome many of the objections to the theory. Differences in behavior or biology that inhibit formation of hybrid zygotes are termed prezygotic isolation. Reinforcement can be shown to be occurring (or to have occurred in the past) by measuring the strength of prezygotic isolation in a sympatric population in comparison to an allopatric population of the same species. Comparative studies of this allow for determining large-scale patterns in nature across various taxa. Mating patterns in hybrid zones can also be used to detect reinforcement.Daniel J. Howard (1993). Reinforcement: origin, dynamics and fate of an evolutionary hypothesis. In: Harrison, R. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Speciation By Reinforcement Schematic
Speciation is the evolutionary process by which populations evolve to become distinct species. The biologist Orator F. Cook coined the term in 1906 for cladogenesis, the splitting of lineages, as opposed to anagenesis, phyletic evolution within lineages. Charles Darwin was the first to describe the role of natural selection in speciation in his 1859 book ''On the Origin of Species''. He also identified sexual selection as a likely mechanism, but found it problematic. There are four geographic modes of speciation in nature, based on the extent to which speciating populations are isolated from one another: allopatric, peripatric, parapatric, and sympatric. Speciation may also be induced artificially, through animal husbandry, agriculture, or laboratory experiments. Whether genetic drift is a minor or major contributor to speciation is the subject of much ongoing discussion. Rapid sympatric speciation can take place through polyploidy, such as by doubling of chromosome numbe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Secondary Contact
Secondary contact is the process in which two allopatricaly distributed populations of a species are geographically reunited. This contact allows for the potential for the exchange of genes, dependent on how reproductively isolated the two populations have become. There are several primary outcomes of secondary contact: extinction of one species, fusion of the two populations back into one, reinforcement, the formation of a hybrid zone, and the formation of a new species through hybrid speciation. Extinction One of the two populations may go extinct due to competitive exclusion after secondary contact. This tends to happen when the two populations have strong reproductive isolation and significant overlap in their niche. A possible way to prevent extinction is if there is an advantage to being rare. For example, sexual imprinting and male-male competition may prevent extinction. The population that goes extinct may leave behind some of its genes in the surviving population if ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Refugium (population Biology)
Refugium, plural refugia, the Latin for "refuge" or "hideaway", may refer to: * Refugium (fishkeeping), an appendage to a marine, brackish, or freshwater fish tank that shares the same water supply * Refugium (population biology), a location of an isolated or relict population of a once widespread animal or plant species ** Last Glacial Maximum refugia specifically, in anthropology * Refugium Range The Refugium Range is a low, small mountain range comprising the mountains/hills of the Brooks Peninsula on northern Vancouver Island, British Columbia, Canada. It has an area of and is a subrange of the Vancouver Island Ranges which in turn for ..., a mountain range on Vancouver Island, British Columbia, Canada See also * Refuge (Buddhism) * Refugium Peccatorum {{disambiguation ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lithobates Blairi
The Plains leopard frog (''Lithobates blairi'') is a spotted frog found in North America. It is sometimes referred to as Blair's leopard frog, named after the noted zoologist and University of Texas professor, Dr. W. Frank Blair. Description The Plains leopard frog grows from in length, and is typically brown in color. Their common name originates from the distinctive irregular, dark colored spotting on their backs. They have long, powerful legs, and are capable of leaping great distances. The frog's spots are brown or greenish brown, and are not ringed in white. There is a distinct white line above the sides of the jaw. The lines along the sides of the back are broken toward the rear, with the short broken section closer to the center of the back. There is often a white spot in the center of the tympanum, and a dark spot on the top the snout. Behavior Although found throughout semiarid regions, the Plains leopard frog is almost always found in or very near permanent water s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lithobates Berlandieri
The Rio Grande leopard frog (''Lithobates berlandieri'' or ''Rana berlandieri'') is a species of aquatic frog native to the southern United States in Texas and New Mexico, and south through Mexico and Central America. It is also sometimes referred to as the Mexican leopard frog. The epithet ''berlandieri'' is in honor of the naturalist Jean Louis Berlandier, who worked for the Mexican government on one of the first biological surveys of Texas.Bour, Roger. (2016) Where and when was Jean Louis Berlandier born? Notes on Jean Louis Berlandier. I. ''Bibliotheca Herpetologica.'' volume 12. number 1 & 2. pages 18-40. Physical description The Rio Grande leopard frogs grow from 2.2 to 4.5 inches in length. They are usually tan, brown, or pale green in color, with distinctive black spotting with prominent light-colored ridges down either side of their backs. Their noses are angular, and they have long, powerful legs with webbed feet. Ecology and behavior The species is primarily aqua ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lithobates Sphenocephalus
''Lithobates sphenocephalus'' or ''Rana sphenocephala'', commonly known as the southern leopard frog, is a medium-sized anuran in the family Ranidae (the true frogs). It is native to eastern North America from Kansas to New York to Florida. It is also an introduced species in some areas. This species lives in cool, clear water in the north, whereas in the south it occurs in warmer turbid and murky waters of coastal and floodplain swamps, twilight zones of caves, and abandoned mines. Description This frog is up to long. It is green or brown in color with a yellowish ridge along each side of the back. Rounded dark spots occur on the back and sides; a light spot is seen on each eardrum. The male has larger fore limbs than the female. The breeding male's vocal sacs are spherical when inflated. The call is described as a "ratchet-like trill",NatureServe. 2015''Lithobates sphenocephalus''.NatureServe Explorer Version 7.1. Accessed 15 June 2016. "chuckling croak",Norman, CSavannah Riv ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
True Frogs
True frogs is the common name for the frog family Ranidae. They have the widest distribution of any frog family. They are abundant throughout most of the world, occurring on all continents except Antarctica. The true frogs are present in North America, northern South America, Europe, Africa (including Madagascar), and Asia. The Asian range extends across the East Indies to New Guinea and a single species (the Australian wood frog (''Hylarana daemelii'')) has spread into the far north of Australia. Typically, true frogs are smooth and moist-skinned, with large, powerful legs and extensively webbed feet. The true frogs vary greatly in size, ranging from small—such as the wood frog (''Lithobates sylvatica'')—to large. Many of the true frogs are aquatic or live close to water. Most species lay their eggs in the water and go through a tadpole stage. However, as in most families of frogs, there is large variation of habitat within the family. There are also arboreal specie ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hyla Gratiosa
''Dryophytes gratiosus'', commonly known as the barking tree frog, is a species of tree frog endemic to the south-eastern United States. Geographic range It is found from Delaware to southern Florida and eastern Louisiana, usually in coastal areas. There are also some isolated colonies in Maryland, Kentucky, and Tennessee. A temporary population was found in New Jersey in 1957. Description ''Dryophytes gratiosus'' is the largest native tree frog in the United States, acquiring its name from the raucous and explosive call. It is in head-body length. It is variable in color, but easily recognizable due to the characteristic dark, round markings on its dorsum. Individuals may be bright or dull green, brown, yellowish, or gray in color with small, grey and green-yellow spots. It has prominent, round toe pads, and the male has a large vocal sac. ''Dryophytes gratiosus'' has skin that is unlike any other species of American frog. Its skin is neither rough and warty not smooth, havi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hyla Cinerea
The American green tree frog (''Dryophytes cinereus'' or ''Hyla cinerea'') is a common arboreal species of New World tree frog belonging to the family Hylidae. This nocturnal insectivore is moderately sized and has a bright green to reddish-brown coloration. Commonly found in the central and southeastern United States, the frog lives in open canopy forests and permanent waters with abundant vegetation. When defending territory, the frog either emits aggressive call signals or grapples with intruders. To avoid predation, the frog hides in its aquatic habitat. Females are larger than males and breed through amplexus. In contrast, males emit low frequency advertisement calls to attract females. During mating competition, males will eavesdrop on neighboring rivals and either adjust their signal timing or remain silent to intercept call signals and mate with approaching females. Androgens energize males to vocalize. Description Many individuals of the American green tree frog are ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Acoustics
Acoustics is a branch of physics that deals with the study of mechanical waves in gases, liquids, and solids including topics such as vibration, sound, ultrasound and infrasound. A scientist who works in the field of acoustics is an acoustician while someone working in the field of acoustics technology may be called an acoustical engineer. The application of acoustics is present in almost all aspects of modern society with the most obvious being the audio and noise control industries. Hearing is one of the most crucial means of survival in the animal world and speech is one of the most distinctive characteristics of human development and culture. Accordingly, the science of acoustics spreads across many facets of human society—music, medicine, architecture, industrial production, warfare and more. Likewise, animal species such as songbirds and frogs use sound and hearing as a key element of mating rituals or for marking territories. Art, craft, science and technology have ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Duration (music)
In music, duration is an amount of time or how long or short a note, phrase, section, or composition lasts. "''Duration'' is the length of time a pitch, or tone, is sounded." A note may last less than a second, while a symphony may last more than an hour. One of the fundamental features of rhythm, or encompassing rhythm, duration is also central to meter and musical form. Release plays an important part in determining the timbre of a musical instrument and is affected by articulation. The concept of duration can be further broken down into those of beat and meter, where beat is seen as (usually, but certainly not always) a 'constant', and rhythm being longer, shorter or the same length as the beat. Pitch may even be considered a part of duration. In serial music the beginning of a note may be considered, or its duration may be (for example, is a 6 the note which begins at the sixth beat, or which lasts six beats?). Durations, and their beginnings and endings, may be d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Audio Frequency
An audio frequency or audible frequency (AF) is a periodic vibration whose frequency is audible to the average human. The SI unit of frequency is the hertz (Hz). It is the property of sound that most determines pitch. The generally accepted standard hearing range for humans is 20 to 20,000 Hz. In air at atmospheric pressure, these represent sound waves with wavelengths of to . Frequencies below 20 Hz are generally felt rather than heard, assuming the amplitude of the vibration is great enough. High frequencies are the first to be affected by hearing loss due to age or prolonged exposure to very loud noises. Sound frequencies above 20 kHz are called ultrasonic. Frequencies and descriptions See also *Absolute threshold of hearing *Hypersonic effect, controversial claim for human perception above 20,000 Hz *Loudspeaker *Musical acoustics * Piano key frequencies *Scientific pitch notation Scientific pitch notation (SPN), also known as American standa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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