|
Divergent Evolution
Divergent evolution or divergent selection is the accumulation of differences between closely related populations within a species, sometimes leading to speciation. Divergent evolution is typically exhibited when two populations become separated by a geographic barrier (such as in allopatric or peripatric speciation) and experience different selective pressures that cause adaptations. After many generations and continual evolution, the populations become less able to interbreed with one another. The American naturalist J. T. Gulick (1832–1923) was the first to use the term "divergent evolution", with its use becoming widespread in modern evolutionary literature. Examples of divergence in nature are the adaptive radiation of the finches of the Galápagos, changes in mobbing behavior of the kittiwake, and the evolution of the modern-day dog from the wolf. The term can also be applied in molecular evolution, such as to proteins that derive from homologous genes. Both o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Darwin's Finches
Darwin's finches (also known as the Galápagos finches) are a group of about 18 species of passerine birds. They are well known for being a classic example of adaptive radiation and for their remarkable diversity in beak form and function. They are often classified as the subfamily Geospizinae or tribe (biology), tribe Geospizini. They belong to the Thraupidae, tanager Family (biology), family and are not closely related to the true finches. The closest known relative of the Galápagos finches is the South American dull-coloured grassquit (''Asemospiza obscura''). They were first collected when Second voyage of HMS Beagle, the second voyage of the ''Beagle'' visited the Galápagos Islands, with Charles Darwin on board as a gentleman naturalist. Apart from the Cocos finch, which is from Cocos Island, the others are found only on the Galápagos Islands. The term "Darwin's finches" was first applied by Percy Lowe in 1936, and popularised in 1947 by David Lack in his book ''Darwin' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Convergent Evolution
Convergent evolution is the independent evolution of similar features in species of different periods or epochs in time. Convergent evolution creates analogous structures that have similar form or function but were not present in the last common ancestor of those groups. The cladistic term for the same phenomenon is Cladogram#Homoplasies, homoplasy. The recurrent evolution of flight is a classic example, as flying pterygota, insects, birds, pterosaurs, and bats have independently evolved the useful capacity of flight. Functionally similar features that have arisen through convergent evolution are ''analogous'', whereas ''homology (biology), homologous'' structures or traits have a common origin but can have dissimilar functions. Bird, bat, and pterosaur wings are analogous structures, but their forelimbs are homologous, sharing an ancestral state despite serving different functions. The opposite of convergence is divergent evolution, where related species evolve different trai ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 DNA contained in a eukaryotic cell; most of the DNA is in the cell nucleus, and, in plants and algae, the DNA also is found in plastids, such as chloroplasts. Mitochondrial DNA is responsible for coding of 13 essential subunits of the complex oxidative phosphorylation (OXPHOS) system which has a role in cellular energy conversion. Human mitochondrial DNA was the first significant part of the human genome to be sequenced. This sequencing revealed that human mtDNA has 16,569 base pairs and encodes 13 proteins. As in other vertebrates, the human mitochondrial genetic code differs slightly from nuclear DNA. Since animal mtDNA evolves faster than nuclear genetic markers, it represents a mainstay of phylogenetics and evolutionary biology. It als ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Husky
Husky is a general term for a type of dog used in the polar regions, primarily and specifically for work as sled dogs. It refers to a traditional northern type, notable for its cold-weather tolerance and overall hardiness. Modern racing huskies that maintain arctic breed traits (also known as Alaskan huskies) represent an ever-changing crossbreed of the fastest dogs. Huskies have continued to be used in sled-dog racing, as well as expedition and trek style tour businesses, and as a means of essential transportation in rural communities. Huskies are also kept as pets, and groups work to find new pet homes for retired racing and adventure-trekking dogs. Etymology The term "husky" first came into usage in the mid to late 1700s. At this time, "Esquimaux" or "Eskimo" was a common term for pre-Columbian Arctic inhabitants of North America. Several dialectal permutations were in use including Uskee, Uskimay and Huskemaw. Thus, dogs used by Arctic people were the dogs of the Husk ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Malamute
The Alaskan Malamute () is a large dog breed, breed of dog that was originally bred for its strength and endurance, to haul heavy freight as a sled dog. It is similar to other arctic breeds such as the husky, the spitz, the Greenland Dog, Canadian Eskimo Dog, the Siberian Husky, and the Samoyed (dog), Samoyed. Lineage Although it is believed that the first dogs arrived in the Americas 12,000 years ago, people and their dogs did not settle in the Arctic until the Paleo-Eskimo people 4,500 years ago, followed by the Thule people 1,000 years ago, with both originating from Siberia. Malamutes were thought to be bred by the Malimiut Iñupiat, Inupiaq people of Alaska's Norton Sound region. The Malamute has been identified as a Dog breed#Basal breeds, basal breed that predates the emergence of the modern breeds in the 19th century. A study in 2013 showed that the Alaskan Malamute has a similar east Asian origin to, but is not clearly related to, the Greenland Dog and the Canadian E ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wolf
The wolf (''Canis lupus''; : wolves), also known as the grey wolf or gray wolf, is a Canis, canine native to Eurasia and North America. More than thirty subspecies of Canis lupus, subspecies of ''Canis lupus'' have been recognized, including the dog and dingo, though grey wolves, as popularly understood, only comprise Wild type, naturally-occurring wild subspecies. The wolf is the largest wild Neontology, extant member of the family Canidae, and is further distinguished from other ''Canis'' species by its less pointed ears and muzzle, as well as a shorter torso and a longer tail. The wolf is nonetheless related closely enough to smaller ''Canis'' species, such as the coyote and the golden jackal, to produce fertile Canid hybrid, hybrids with them. The wolf's fur is usually mottled white, brown, grey, and black, although subspecies in the arctic region may be nearly all white. Of all members of the genus ''Canis'', the wolf is most Generalist and specialist species, specializ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Origin Of The Domestic Dog
The domestication of the dog was the process which led to the domestic dog. This included the dog's genetic divergence from the wolf, its domestication, and the emergence of the first dogs. Genetic studies suggest that all ancient and modern dogs share a common ancestry, descending from an ancient, now-extinct wolf population – or closely related wolf populations – which was distinct from the modern wolf lineage. The dog's similarity to the grey wolf is the result of substantial dog-into-wolf gene flow, with the modern grey wolf being the dog's nearest living relative. An extinct Late Pleistocene wolf may have been the ancestor of the dog. The dog is a wolf-like canid. The genetic divergence between the dog's ancestor and modern wolves occurred between 20,000 and 40,000 years ago, just before or during the Last Glacial Maximum (20,000–27,000 years ago). This timespan represents the upper time-limit for the commencement of domestication because it is the time of divergence ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Genomic Sequencing
DNA sequencing is the process of determining the nucleic acid sequence – the order of nucleotides in DNA. It includes any method or technology that is used to determine the order of the four bases: adenine, thymine, cytosine, and guanine. The advent of rapid DNA sequencing methods has greatly accelerated biological and medical research and discovery. Knowledge of DNA sequences has become indispensable for basic biological research, DNA Genographic Projects and in numerous applied fields such as medical diagnosis, biotechnology, forensic biology, virology and biological systematics. Comparing healthy and mutated DNA sequences can diagnose different diseases including various cancers, characterize antibody repertoire, and can be used to guide patient treatment. Having a quick way to sequence DNA allows for faster and more individualized medical care to be administered, and for more organisms to be identified and cataloged. The rapid advancements in DNA sequencing technology ha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Geographic Isolation
Allopatric speciation () – also referred to as geographic speciation, vicariant speciation, or its earlier name the dumbbell model – is a mode of speciation that occurs when biological populations become geographically isolated from each other to an extent that prevents or interferes with gene flow. Various geographic changes can arise such as the movement of continents, and the formation of mountains, islands, bodies of water, or glaciers. Human activity such as agriculture or developments can also change the distribution of species populations. These factors can substantially alter a region's geography, resulting in the separation of a species population into isolated subpopulations. The vicariant populations then undergo genetic changes as they become subjected to different selective pressures, experience genetic drift, and accumulate different mutations in the separated populations' gene pools. The barriers prevent the exchange of genetic information between th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Galápagos Islands
The Galápagos Islands () are an archipelago of volcanic islands in the Eastern Pacific, located around the equator, west of the mainland of South America. They form the Galápagos Province of the Republic of Ecuador, with a population of slightly over 33,000 (2020). The province is divided into the Cantons of Ecuador, cantons of San Cristóbal Island, San Cristóbal, Santa Cruz Island (Galápagos), Santa Cruz, and Isabela Island (Galápagos), Isabela, the three most populated islands in the chain. The Galápagos are famous for their large number of Endemism, endemic species, which were studied by Charles Darwin in the 1830s and inception of Darwin's theory, inspired his theory of evolution by means of natural selection. All of these islands are protected as part of Ecuador's Galápagos National Park and Galápagos Marine Reserve, Marine Reserve. Thus far, there is no firm evidence that Polynesian expansion, Polynesians or the indigenous peoples of South America, Indigenous pe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Darwin's Finches
Darwin's finches (also known as the Galápagos finches) are a group of about 18 species of passerine birds. They are well known for being a classic example of adaptive radiation and for their remarkable diversity in beak form and function. They are often classified as the subfamily Geospizinae or tribe (biology), tribe Geospizini. They belong to the Thraupidae, tanager Family (biology), family and are not closely related to the true finches. The closest known relative of the Galápagos finches is the South American dull-coloured grassquit (''Asemospiza obscura''). They were first collected when Second voyage of HMS Beagle, the second voyage of the ''Beagle'' visited the Galápagos Islands, with Charles Darwin on board as a gentleman naturalist. Apart from the Cocos finch, which is from Cocos Island, the others are found only on the Galápagos Islands. The term "Darwin's finches" was first applied by Percy Lowe in 1936, and popularised in 1947 by David Lack in his book ''Darwin' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Parallel Evolution
Parallel evolution is the similar development of a trait in distinct species that are not closely related, but share a similar original trait in response to similar evolutionary pressure.Zhang, J. and Kumar, S. 1997Detection of convergent and parallel evolution at the amino acid sequence level. ''Mol. Biol. Evol.'' 14, 527-36. Parallel vs. convergent evolution Given a trait that occurs in each of two lineages descended from a specified ancestor, it is possible in theory to define parallel and convergent evolutionary trends strictly, and distinguish them clearly from one another. However, the criteria for defining convergent as opposed to parallel evolution are unclear in practice, so that arbitrary diagnosis is common. When two species share a trait, evolution is defined as parallel if the ancestors are known to have shared that similarity; if not, it is defined as convergent. However, the stated conditions are a matter of degree; all organisms share common ancestors. Scientis ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
