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Adaptive Radiation
In evolutionary biology, adaptive radiation is a process in which organisms diversify rapidly from an ancestral species into a multitude of new forms, particularly when a change in the environment makes new resources available, alters biotic interactions or opens new environmental niches. Starting with a single ancestor, this process results in the speciation and phenotypic adaptation of an array of species exhibiting different morphological and physiological traits. The prototypical example of adaptive radiation is finch speciation on the Galapagos ("Darwin's finches"), but examples are known from around the world. Characteristics Four features can be used to identify an adaptive radiation: #A common ancestry of component species: specifically a ''recent'' ancestry. Note that this is not the same as a monophyly in which ''all'' descendants of a common ancestor are included. #A phenotype-environment correlation: a ''significant'' association between environments and the morp ... [...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 their remarkable diversity in beak form and function. They are often classified as the subfamily Geospizinae or tribe Geospizini. They belong to the tanager family and are not closely related to the true finches. The closest known relative of the Galápagos finches is the South American '' Tiaris obscurus''. They were first collected when 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's Finches''. Lack based his analysis on the large collection of museum specimens collected by the 1905–06 Galápagos expedition of the California Academy ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rift Valley Lakes
The Rift Valley lakes are a series of lakes in the East African Rift valley that runs through eastern Africa from Ethiopia in the north to Malawi in the south, and includes the African Great Lakes in the south. These include some of the world's oldest lakes, deepest lakes, largest lakes by area, and largest lakes by volume. Many are freshwater ecoregions of great biodiversity, while others are alkaline "soda lakes" supporting highly specialised organisms. The Rift Valley lakes are well known for the evolution of at least 800 cichlid fish species that live in their waters. More species are expected to be discovered. The World Wide Fund for Nature has designated these lakes as one of its Global 200 priority ecoregions for conservation. Geology Lake Malawi and Lake Tanganyika have formed in the various valleys of the East African Rift zone. Ecology Lake Kivu's "still waters ... hide another face: dissolved within are billions of cubic meters of flammable methane and more stil ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Geospiza
''Geospiza'' is a genus of bird in the tanager family Thraupidae. All species in the genus are endemic to the Galápagos Islands. Together with related genera, they are collectively known as Darwin's finches. Although in the past, they were classified in the bunting and American sparrow family Emberizidae, more recent studies have shown they belong in the tanager family. Taxonomy and species list The genus ''Geospiza'' was introduced in 1837 by the English ornithologist John Gould with the large ground finch as the type species. The genus name derives from the two Ancient Greek words (), meaning "earth", and (), a catch-all term for ''finch''-like birds. The member of the genus form part of a group collectively known as Darwin's finches. Although traditionally placed with the buntings and New World sparrows in the family Emberizidae, molecular phylogenetic studies have shown that Darwin's finches are members of the subfamily Coerebinae within the tanager family Thraupidae. The ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Peter And Rosemary Grant
Peter Raymond Grant (born October 26, 1936) and Barbara Rosemary Grant (born October 8, 1936) are a British married couple who are evolutionary biologists at Princeton University. Each currently holds the position of emeritus professor. They are known for their work with Darwin's finches on Daphne Major, one of the Galápagos Islands. Since 1973, the Grants have spent six months of every year capturing, tagging, and taking blood samples from finches on the island. They have worked to show that natural selection can be seen within a single lifetime, or even within a couple of years. Charles Darwin originally thought that natural selection was a long, drawn out process but the Grants have shown that these changes in populations can happen very quickly. In 1994, they were awarded the Leidy Award from the Academy of Natural Sciences of Philadelphia. The Grants were the subject of the book '' The Beak of the Finch: A Story of Evolution in Our Time'' by Jonathan Weiner, which won ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sympatry
In biology, two related species or populations are considered sympatric when they exist in the same geographic area and thus frequently encounter one another. An initially interbreeding population that splits into two or more distinct species sharing a common range exemplifies sympatric speciation. Such speciation may be a product of reproductive isolation – which prevents hybrid offspring from being viable or able to reproduce, thereby reducing gene flow – that results in genetic divergence. Sympatric speciation may, but need not, arise through secondary contact, which refers to speciation or divergence in allopatry followed by range expansions leading to an area of sympatry. Sympatric species or taxa in secondary contact may or may not interbreed. Types of populations Four main types of population pairs exist in nature. Sympatric populations (or species) contrast with parapatric populations, which contact one another in adjacent but not shared ranges and do not ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Medium Ground Finch
The medium ground finch (''Geospiza fortis'') is a species of bird in the family Thraupidae. It is endemic to the Galapagos Islands. Its primary natural habitat is tropical shrubland. One of Darwin's finches, the species was the first which scientists have observed evolving in real-time. The population of medium ground finches has been experiencing inbreeding depression due to small population numbers. Inbreeding depression occurs when there is a decrease in fitness due to individuals mating with genetic relatives. Typically, this leads to a loss of genetic diversity and a reduction in heterozygosity. Description Like the other members of its genus, the medium ground finch is strongly sexually dimorphic; the female's plumage is brown and streaky, while male's is solid black, with white tips to the undertail coverts. The bird measures in length—which falls between the lengths of the small and large ground finches. The bill of this species is quite variable in size, though the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Small Ground Finch
The small ground finch (''Geospiza fuliginosa'') is a species of bird in the tanager family Thraupidae. Endemic to the Galápagos Islands, it is common and widespread in shrubland, woodland, and other habitats on most islands in the archipelago. It commonly feeds on small seeds and parasites from the skins of Galápagos land and marine iguanas and Galápagos tortoises. Taxonomy and systematics The small ground finch is one of Darwin's finches, a group of closely related birds which evolved on the Galápagos Islands. The group is related to the ''Tiaris'' grassquits, which are found in South America and the Caribbean. When Charles Darwin first collected the species in 1835, he thought it was a finch. John Gould, who officially described Darwin's specimens, agreed, placing it in the genus ''Fringilla'' with the Old World finches. By 1841, Gould had changed his mind, moving this and five other species into the new genus ''Geospiza'' — still a genus of finches, but distinct fr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Large Ground Finch
The large ground finch (''Geospiza magnirostris'') is a species of bird. One of Darwin's finches, it is now placed in the family Thraupidae and was formerly in the Emberizidae. It is endemic Endemism is the state of a species being found 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 found else ... to the Galapagos Islands, and is found in the arid zone of most of the archipelago, though it is absent from the southeastern islands ( Floreana, Española, San Cristóbal, and Santa Fé). It is the largest species of Darwin's finch both in total size and size of beak. It has a large, short beak for cracking nuts to get food. Gallery File:Large ground finch (4229044630).jpg, left, Large ground finch File:Geospiza magnirostris.jpg, left, One of Darwin's finches. Charles and Chatham Islands, Galapagos Archipelago. References Geospiza ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tanager
The tanagers (singular ) comprise the bird family Thraupidae, in the order Passeriformes. The family has a Neotropical distribution and is the second-largest family of birds. It represents about 4% of all avian species and 12% of the Neotropical birds. Traditionally, the family contained around 240 species of mostly brightly colored fruit-eating birds. As more of these birds were studied using modern molecular techniques, it became apparent that the traditional families were not monophyletic. ''Euphonia'' and ''Chlorophonia'', which were once considered part of the tanager family, are now treated as members of the Fringillidae, in their own subfamily (Euphoniinae). Likewise, the genera ''Piranga'' (which includes the scarlet tanager, summer tanager, and western tanager), '' Chlorothraupis'', and '' Habia'' appear to be members of the cardinal family, and have been reassigned to that family by the American Ornithological Society. Description Tanagers are small to medium-sized b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Finch
The true finches are small to medium-sized passerine birds in the family Fringillidae. Finches have stout conical bills adapted for eating seeds and nuts and often have colourful plumage. They occupy a great range of habitats where they are usually resident and do not migrate. They have a worldwide distribution except for Australia and the polar regions. The family Fringillidae contains more than two hundred species divided into fifty genera. It includes species known as siskins, canaries, redpolls, serins, grosbeaks and euphonias. Many birds in other families are also commonly called "finches". These groups include the estrildid finches (Estrildidae) of the Old World tropics and Australia; some members of the Old World bunting family (Emberizidae) and the New World sparrow family (Passerellidae); and the Darwin's finches of the Galapagos islands, now considered members of the tanager family (Thraupidae).Newton (1973), Clement ''et al.'' (1993) Finches and canaries were us ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Costa Rica
Costa Rica (, ; ; literally "Rich Coast"), officially the Republic of Costa Rica ( es, República de Costa Rica), is a country in the Central American region of North America, bordered by Nicaragua to the north, the Caribbean Sea to the northeast, Panama to the southeast, the Pacific Ocean to the southwest, and Maritime boundary, maritime border with Ecuador to the south of Cocos Island. It has a population of around five million in a land area of . An estimated 333,980 people live in the capital and largest city, San José, Costa Rica, San José, with around two million people in the surrounding metropolitan area. The sovereign state is a Unitary state, unitary Presidential system, presidential Constitution of Costa Rica, constitutional republic. It has a long-standing and stable democracy and a highly educated workforce. The country spends roughly 6.9% of its budget (2016) on education, compared to a global average of 4.4%. Its economy, once heavily dependent on agricultu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cocos Island
Cocos Island ( es, Isla del Coco) is an island in the Pacific Ocean administered by Costa Rica, approximately southwest of the Costa Rican mainland. It constitutes the 11th of the 13 districts of Puntarenas Canton of the Province of Puntarenas. With an area of approximately , the island is more or less rectangular in shape. It is the southernmost point of geopolitical North America if non-continental islands are included. The entirety of Cocos Island has been designated a Costa Rican National Park since 1978, and has no permanent inhabitants other than Costa Rican park rangers. Surrounded by deep waters with counter-currents, Cocos Island is admired by scuba divers for its populations of hammerhead sharks, rays, dolphins and other large marine species. The wet climate and oceanic qualities give Cocos an ecological character that is not shared with either the Galápagos Archipelago or any of the other islands (for example, Malpelo, Gorgona or Coiba) in the eastern Pacific O ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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