Biogeography as Evidence That Evolution Accounts for Diversity of Life

2) Biogeography is one source of designate that evolution accounts for the diverseness of liveness. Biogeography is the study of the geographical scattering of species and has contri simplyed evidence for descent from common ancestors, which was hypothesized by Charles Darwin. Darwin and Alfred Wallace were both very interested in biogeography, which provided Darwin with evidence for evolution. Species distri moreoverion potful be accounted for by ecological factors or by historical factors. The terce major historical factors affecting geographic dispersal be dispersal, extinguishing and vicariance.Is cut biogeography has been extensively studied to show the evolution of species due to geographic barriers. Biogeography along with the history of the earth lends supporting evidence to evolution and the diversity of life on earth. Darwin showed that biogeographic facts make sense if a species has a defined site of origin, achieves a broader distribution by dispersal, and beco mes modified giving fount to descendent species in the regions in which it migrates. He noniced that unrelated organisms watch parts of the world with similar climates and habitats, such(prenominal) as Old and mod World organisms.Darwin also found that organisms of various regions may be unlike due to barriers or obstacles that may limit migration. He also decl bed that there is a relation surrounded by inhabitants of the same continent or sea but that species differ from place to place. An example of this is aquatic rodents of south America ar related to mountainous and grassland rodents of South America, but not to aquatic rodents of North America. Alfred Wallace noticed that several higher taxa had similar distributions and that the base of biota is more uniform within certain regions then amidst them.He had collected specimens in the Malay Archipelago and had thought of natural selection. He did extensive dramatics work in the Amazon and noticed that geographic barrie rs, such as the Amazon River itself, separated the regorges of closely related species. These observations conduct him to designate several biogeographic realms. He observe that the fauna of Australia and Asia were antithetic and the break between them is known as the Wallace Line. Historical factors affecting geographic distributions of species include extinction, dispersal, and vicariance. Extinction of certain opulations reduces the distribution of species but it also allows for diversification. Extinctions be selective in that some species are more likely to give way then former(a)s. For example, gastropods with wide geographic and ecological distributions and those with many species survived the end-Permian extinction. Extinction suffer lead to diversification in that it resets the stage for evolutionary radiations, perhaps by permitting the appearance of vernal community structures. Futuyma suggests that the extinction of one group permits the heyday of others, which is also shown in the fossil record.Dispersal and vicariance are the major hypotheses attributing to a taxons distribution. An example of vicarance is taxa that have members on antithetical land masses in the Southern Hemisphere, which is hypothesized to be due to the breakup of Gondwanaland separate descendents of common ancestors. America, Africa, Madagascar, and India are all home to the freshwater fishes, cichlids. Molecular phyletic analyses has shown that two sister clades of cichlids have been found, one consisting of Madagas bed and Indian species, and the other of two monophyletic groups, one in Africa and one in South America.However, the splits between the clades are more recent than the breakup of Gondwanaland which suggests that perhaps the cichlids achieved their distribution by dispersal. Both vicariance and dispersal could be the likely cause of the geographic distribution of cichlids. Species expand their ranges by dispersal which is a critical process for geogra phic isolation in evolution and the current geographic distributions. Most species are restricted to certain biogeographic realms by their dispersal ability but many species have expanded their range due to human transplant.For example, the European starling has expanded in North America following its introduction into upstart York City in 1896 (Futuyma, 2005). Transplanted species may disrupt the ecosystem at its new arrangement by evolving and adapting to the new environment, possibly causing the extinction of native species. adjustment to the environment as a primary product of evolution was suggested by Jean Baptiste Lamarck who believed that evolution is the best explanation of the diversity of life. Vicariance is the insularism of populations of a widespread species by barriers arising from changes in climate, geology, or habitat.Vicariance force out lead to speciation if populations are separated by a geographic barrier and evolve transmittable reproductive isolation su ch that if the barrier disappears, the species can no long-term interbreed. Natural selection is a powerful evolutionary force and then the genetic changes that result in reproductive isolation in vicariant speciation are likely due to adaptational evolution. Several geological processes can fraction a population into two, such as a mountain range emerging, rivers, lakes, or land bridges.Island biogeography is a very good example of evidence for evolution. Islands are loosely where endemic species of plants and animals are found but Darwin observed that most island species are closely related to species from the nearest ma landlocked or neighbouring island. both islands that have similar environments in opposite parts of the world are populated by species that are taxonomically affiliated with the plants and animals of the nearest mainland which generally has a different environment.Speciation may go on islands if a species that disperses from a mainland to an island succeeds in its new environment and gives rise to several new species as populations spread to other islands. Once isolated, geographically separated populations become genetically differentiated as a result of mutation and other processes such as natural selection. Environmental factors are likely to be different from one place to another so natural selection can contribute to geographic variation, differences in the gene pool between populations.Speciation is lots a gradual process as the reproductive barriers between the groups is save partial in the beginning but leads to complete reproduction separation (Campbell and Reece, 2002). An example of vicariance and island biogeography is the finches on the Galapagos Islands. Darwin noticed that the finches he collected from the islands were very similar, but that they were in fact different species. Some were unique to individual islands, small-arm other species were distributed on two or more islands that were close together. hot finch s pecies had arisen from an ancestral form by the gradual accumulation of adaptations to a different environment. For example, the different beak sizes of the finches are adapted to the specific food procurable to them on their home island. This is an example of species adapting and evolving to suit their new environment. The Hawaiian Islands are another example of the worlds showcase of evolution and island biogeography. distributively island started bare but was gradually populated by species that either rode nautical currents or blew over in the wind, either from distant islands or continents.The animal(prenominal) diversity of each island provides many different environmental opportunities for evolutionary dissimilarity by natural selection. Many of the plants and animals that are currently found on the islands are found nowhere else in the world, they are endemic to the Hawaiian archipelago (Campbell and Reece, 2002). The history of earth also helps to explain the current ge ographic distribution of species. For example, the emergence of volcanic islands such as the Galapagos opens new environments for species to inhabit and adaptive radiation fills many of the available niches with new species.On a globular scale, continental drift is a major factor correlated with the spatial distribution of life and with such evolutionary episodes as mass extinctions followed by increases in biological diversity. The continents drift about earths come along on plates of crust floating on the hot mantle and their positions can therefore change relative to one another. At the end of the Paleozoic era, plate movements brought all the landmasses together into a super continent named Pangaea. Species that had been evolving in isolation were brought together at this point and forced to compete.The formation of Pangea reduce shoreline, drained shallow coastal areas, changed the climate and increased the area inland destroying a considerable amount of habitat and reshapin g biodiversity. During the Mesozoic, Pangaea broke apart creating new continents that became separate evolutionary areas allowing flora and fauna to diverge. The diversity of life on earth is due to millions of years of evolution. Darwin and Wallace were both important figures in the field of biogeography as their interest and research led to ideas that are still plain today.Historical geographic factors and the history of the earth are a few aspects that have led to current biodiversity. Biogeography shows compelling evidence that species evolve by natural selection by adapting to new environments. Speciation will continue to occur as the environment changes and as the continents continue to drift. References Campbell, N. A, and Reece, J. B. 2002. Biology Sixth Edition. genus Benzoin Cummings, San Francisco. Futuyma, D. J. 2005. Evolution. Sinauer Associates Inc. , Massachusetts.