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Genetic drift and evolution
Genetic drift and evolution
Genetic drift and evolution
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Before tackling the issue of the level at which speciation occurs as the result of divergence, we must first establish the definition of speciation. In the scientific community, this terminology is associated with the formation of new and distinctive species, from which a single evolutionary line splits into two or more genetically independent ones (Cook 1906). In essence, from one common ancestor derives two descendent species. Taking into consideration the controversial nature of what constitute a species, this is will refer to species as related individuals that resemble one another; they are able to breed with themselves, but not with members of another species (Rosenzweig 1995).
Now that we have established the meaning of speciation and species, we can proceed to answering the question of when speciation takes place. Speciation is more probable as a result of geographical isolation, which gives rise to reproductive isolation as a way to reinforce a divergent event that has already occurred. Since it has been established that the simplest form of speciation is lineage splitting, we must thus, understand how the split of one common ancestor can result in the formation of two separate and distinct species. Literature affirms that divergence of species is the outcome of accumulated differences between groups, which leads to the formation of new species (Salzburger et al. 2002). Usually this is a result of diffusion of the same species to different and isolated environments.
The isolation of environment plays the role of blocking the gene flow among the distinct population, allowing differentiated fixation of characteristics through natural selection to take place (Salzburger et al. 2002). Provided that most geographic...
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...ecies. Arguments and supporting examples were presented to illustrate how the formation of two or more species requires geographical isolation in order for reproductive isolation and natural selection to produce distinctive gene pools, thus resulting in the emergence of new species.
Bibliography
Cook, O.F. "Factors of species-formation." Science (1906): 506-507.
Hoskin, Conrad J, et al. "Reinforcement drives rapid allopatric speciation." Nature (2005): 437: 1353–1356.
Rosenzweig, M.L. Species Diversity in Space and Time. Cambridge: Cambridge University Press, 1995.
Salzburger, W, S Baric and C Sturnmbauer. "Speciation via introgressive hybridization in East African cichlids." Mol Ecol (2002): 619 - 625.
Sutera, R. 2001. The Origin of Whales and the Power of Independent Evidence. The Talk Origins Archive.
1) Carroll, R. L. 1988. Vertebrate Paleontology and Evolution. W. H. Freeman and Company, New York.
J. G. M. Thewissen and his colleagues changed the way in which scientists thought about the early lifestyles of whales. The evolution of the ancient artiodactyls was discovered to be joined with the well-known group of cetaceans. The tertiary period was a time of terrestrial life forms. Every mammal walked the earth. It wasn’t uncommon to see a whale running through the grasslands or shark sleeping on the coast of a land mass. It was a time when mammals roamed freely and unconfined by the limits of the ocean. Now that scientists have this newly found knowledge, it is time the scientists further investigate “why?”
The second of Tinbergen’s questions Phylogeny looks at the evolutionary explanations of development, as opposed to just how behaviour has adapted, including mutations in response to environmental changes. Some of these mutations remain in species even after necessity has gone, and can influence future characteristics of that species. The third of Tinbergen’s questions looks at Causation,...
As every species in the world developed, it's sub-species and it's further strains and breeds under those have evolved for a very specific reason - the preservation of the species, and ultimately, life itself. Each species is like a tree, with hundreds of branches, each leading to thousands of other branches. Each branch of the tree is slightly different from the one beside it, due to living in a different environment it has had to adapt and the resulting differences are due to the combination - the formula - of genes, which has survived the best in whatever environment it has encountered. Because of this branching of the species, whenever a particular disease, a natural phenomenon, or a new predator has arrived on the scene, the species has always been diverse enough to continue, as there will be one branch of the tree which has the immunity, adapted over time, in order to defend itself or escape from the catastrophe. This method, special branching, has ensured the survival of various species for thousands of years, and is in fact the reason for the existance of different species.
Some individuals have developed different traits to help them in the process of intra-sexual competition. The organisms with more distinctive traits have greater reproductive success. More genes of those traits are then ‘selected’ and are passed onto the offspring of the organisms. Throughout time variability in these traits becomes
Species that now populate the Earth come from other species that existed in the past, through a process of descent with modification. Biological evolution is the historical process of transformation from one species in other descendant species, including the extinction of most of the species that have ever existed. One of the most romantic ideas in the evolution of life is that any two living organisms, different as they are, they share a common ancestor sometime in the past. We and any current chimpanzee share an ancestor of 5 million years. We also have a common ancestor with any bacteria that exist today, although time this predecessor to soar in this case more than 3000 million years. However, the idea of evolution by itself is an open concept, is a mechanical description of change does not say anything about the engine or the creative force behind the transformation. Thus, in principle, evolution can be driven by immanent laws of matter, or a divine creator or by blind forces,
The origin of modern day whales, a mystery that has puzzled paleontologists for years, may have just been solved with the discovery of an ankle bone. This discovery might sound simple and unimportant, but the bones of these ancient animals hold many unanswered questions and provide solid proof of origin and behavior. The relationship between whales and other animals has proven to be difficult because whales are warm-blooded, like humans, yet they live in the sea. The fact that they are warm-blooded suggests that they are related to some type of land animal. However, the questions of exactly which animal, and how whales evolved from land to water, have remained unanswered until now.
Work Cited Colby, Chris. A. Web. " An Introduction to Evolutionary Biology." 28 August 2015.
...e single origin perspective but not the multiregional perspective (1988). For example, the first appearance of Homo sapiens raises problems. The newest fossils of Homo sapiens were discovered in Africa while Europe, the Far East and Australia have the oldest fossils (Stringer & Andrew 1988). If there was one linearly evolving species we should see the oldest fossils in Africa. Also, Although Europe and southwest Asia have the most complete fossil record there is an absence of Neanderthal and modern Homo sapiens transitional fossils, which goes against the idea that species evolved together (Stringer & Andrew, 1988). The fossils better describe the single origin perspective.
Rantala, M. J., and Roff, D. A. 2006. Analysis of the importance of genotypic variation,
Charles Darwin’s theory of natural selection explains the general laws by which any given species transforms into other varieties and species. Darwin extends the application of his theory to the entire hierarchy of classification and states that all forms of life have descended from one incredibly remote ancestor. The process of natural selection entails the divergence of character of specific varieties and the subsequent classification of once-related living forms as distinct entities on one or many levels of classification. The process occurs as a species varies slightly over the course of numerous generations. Through inheritance, natural selection preserves each variation that proves advantageous to that species in its present circumstances of living, which include its interaction with closely related species in the “struggle for existence” (Darwin 62).
One of the previous papers in English class required the class to pick a paper to explore, this question will be concentrated on further in the synthesis essay. What evidence do scientist have to prove that prehistoric sharks existed? The reason behind picking this question wasn’t just to find proof that these monsters swam the seas, but to learn more about them from different resources. One of the resources that were used was a chapter in Angelo Mojetta’s book Sharks, called “ The Birth Of A Legend”. The other resource that was used for information was an article in Discovery Channels website called “ Prehistoric Sharks”. Sharks and Discovery Channel are the two resources that led to many other questions about their different, and similar views on prehistoric sharks existence.
The literature does provide evidence for my hypothesis and also provides a clearer picture as to how frequent and to what extent the interbreeding is believed to occur. Examining these articles will introduce the new findin...
“Darwin's theory about how species originated doubled as a theory of how they vanished. Extinction and evolution were to each other the warp and weft of life’s fabric, or, if you prefer, two sides of the same coin. “The appearance of new forms and the disappearance of old forms” were, Darwin wrote, “bound together.” Driving both was a struggle for existence,” which rewarded the fit and eliminated the less so.” Kolbert, page 54.
Evolution is defined as the change of hereditary characteristics of populations over generations (Caroll, 2009). The environment is continually changing therefore organisms have to change in order to stand the changes in environment so they can survive and reproduce (Caroll, 2009). Regular change in genetic material of organisms over generations can lead to the development of new species that are more adapted to the environment (Caroll, 2009). It is said that failure to evolve may lead to extinction of a species (Caroll, 2009).