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==Divergent Evolution ==

==Divergent Evolution ==

When people hear the word "evolution," they most commonly think of divergent evolution,<ref>http://bioweb.cs.earlham.edu/9-12/evolution/HTML/converge.html</ref> the evolutionary pattern in which two species gradually become increasingly different. Divergent evolution refers to a group from a specific population developing into a new species. In order to adapt to various environmental conditions, the two groups are said to develop into distinct species due to differences in the demands driven by the environmental circumstances. On a large scale, divergent evolution is said to be responsible for the creation of the current diversity of life on earth from the first living cells. On a smaller scale, it is claimed to be responsible for the evolution of humans and apes from a common primate ancestor. On a molecular scale, it is what would describe the appearance of new catalytic functions of enzymes and membrane protein topology.<ref>http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=retrieve&db=pubmed&list_uids=11395407&dopt=Abstract</ref><ref>http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=17552</ref>

When people hear the word "evolution," they most commonly think of divergent evolution,<ref>http://bioweb.cs.earlham.edu/9-12/evolution/HTML/converge.html</ref> the evolutionary pattern in which two species gradually become increasingly different. Divergent evolution refers to a group from a specific population developing into a new species. In order to adapt to various environmental conditions, the two groups are said to develop into distinct species due to differences in the demands driven by the environmental circumstances. On a large scale, divergent evolution is said to be responsible for the creation of the current diversity of life on earth from the first living cells. On a smaller scale, it is claimed to be responsible for the evolution of humans and apes from a common primate ancestor. On a molecular scale, it is what would describe the appearance of new catalytic functions of enzymes and membrane protein topology.<ref>https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=retrieve&db=pubmed&list_uids=11395407&dopt=Abstract</ref><ref>http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=17552</ref>

To the extent that divergence only involves a "sorting out" of existing genes, and not the generation of new genetic [[information]], [[creationism|creationists]] agree that divergence occurs.

To the extent that divergence only involves a "sorting out" of existing genes, and not the generation of new genetic [[information]], [[creationism|creationists]] agree that divergence occurs.

===Examples of Divergence===

===Examples of Divergence===

There are many examples<ref>http://www.sciencemag.org/cgi/content/abstract/290/5491/516</ref><ref>http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11308083&dopt=Abstract</ref> of divergence in nature. If a freely-interbreeding population on an island is separated by a barrier, such as the presence of a new river, then over time, the organisms may start to diverge. If the opposite ends of the island have different pressures acting upon it, this may result in divergence. Or, if a certain group of birds in a population of other bird of the same species varies from their migratory track due to abnormal wind fluctuations, they may end up in a new environment. If the food source is such that only birds of the population with a variant beak are able to feed, then this trait will become more common by virtue of its selective survival advantage. The same species in the original geographical location and having the original food source do not require this beak trait and will, therefore, not change in the same way.

There are many examples<ref>http://www.sciencemag.org/cgi/content/abstract/290/5491/516</ref><ref>https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11308083&dopt=Abstract</ref> of divergence in nature. If a freely-interbreeding population on an island is separated by a barrier, such as the presence of a new river, then over time, the organisms may start to diverge. If the opposite ends of the island have different pressures acting upon it, this may result in divergence. Or, if a certain group of birds in a population of other bird of the same species varies from their migratory track due to abnormal wind fluctuations, they may end up in a new environment. If the food source is such that only birds of the population with a variant beak are able to feed, then this trait will become more common by virtue of its selective survival advantage. The same species in the original geographical location and having the original food source do not require this beak trait and will, therefore, not change in the same way.

Divergence appears to have also occurred in the red fox and the kit fox. While the kit fox lives in the desert where its coat helps disguise it from its predators, the red fox lives in forests, where the red coat blends into its surroundings. In the desert, the heat makes it difficult for animals to eliminate body heat. The ears of the kit fox have a greater surface area so that it can more efficiently remove excess body heat. Their different adaptations are determined primarily by the different environmental conditions and adaptation requirements, not on genetic differences.<!-- I don't understand this.--> If they were in the same environment, it is likely that they would evolve similarly. Divergence is supported by DNA analysis where the species that diverged can be shown to be genetically similar.

Divergence appears to have also occurred in the red fox and the kit fox. While the kit fox lives in the desert where its coat helps disguise it from its predators, the red fox lives in forests, where the red coat blends into its surroundings. In the desert, the heat makes it difficult for animals to eliminate body heat. The ears of the kit fox have a greater surface area so that it can more efficiently remove excess body heat. Their different adaptations are determined primarily by the different environmental conditions and adaptation requirements, not on genetic differences.<!-- I don't understand this.--> If they were in the same environment, it is likely that they would evolve similarly. Divergence is supported by DNA analysis where the species that diverged can be shown to be genetically similar.

==Convergent Evolution==

==Convergent Evolution==

Convergent evolution<ref>http://www.pbs.org/wgbh/evolution/library/01/4/l_014_01.html</ref> is where creatures are believed to have independently evolved similar features.  Convergence causes difficulties in fields of study such as comparative anatomy. Convergent evolution takes place when species of different ancestry begin to share analogous traits because of a shared environment or other selection pressure. Environmental circumstances that require similar developmental or structural alterations for the purposes of adaptation are thought to lead to convergent evolution even though the species differ in descent. These adaptation similarities that arise as a result of the same selective pressures can be misleading to scientists studying the natural evolution of a species.  Convergent evolution also creates problems for paleontologists using evolutionary patterns in taxonomy, or the categorization and classification of various organisms based on relatedness. It often leads to incorrect relationships and false evolutionary predictions.

Convergent evolution<ref>https://www.pbs.org/wgbh/evolution/library/01/4/l_014_01.html</ref> is where creatures are believed to have independently evolved similar features.  Convergence causes difficulties in fields of study such as comparative anatomy. Convergent evolution takes place when species of different ancestry begin to share analogous traits because of a shared environment or other selection pressure. Environmental circumstances that require similar developmental or structural alterations for the purposes of adaptation are thought to lead to convergent evolution even though the species differ in descent. These adaptation similarities that arise as a result of the same selective pressures can be misleading to scientists studying the natural evolution of a species.  Convergent evolution also creates problems for paleontologists using evolutionary patterns in taxonomy, or the categorization and classification of various organisms based on relatedness. It often leads to incorrect relationships and false evolutionary predictions.

As explained further below, creationists claim that convergence is merely a rationalization for evidence that contradicts divergence.

As explained further below, creationists claim that convergence is merely a rationalization for evidence that contradicts divergence.

One example is the complex plumage patterns that seem to have evolved independently among many very different bird species.<ref>http://www.sciencemag.org/cgi/content/summary/303/5665/1779</ref>

One example is the complex plumage patterns that seem to have evolved independently among many very different bird species.<ref>http://www.sciencemag.org/cgi/content/summary/303/5665/1779</ref>

A molecular example of Parallel Evolution is the ligand specificity of repressors and periplasmic sugar-binding proteins.<ref>http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=12598694</ref>

A molecular example of Parallel Evolution is the ligand specificity of repressors and periplasmic sugar-binding proteins.<ref>https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=12598694</ref>

Parallel evolution is exemplified in the case of the tympanal and atympanal mouthears in hawkmoths, or Sphingidae species. These insects have developed a tympanum, or eardrum, similar to humans as a means to communicate through sound. Sounds induce vibrations of a membrane that covers the tympanum, known as the tympanic membrane. These vibrations are detected by small proteins at the surface of the tympanic membrane called auditory receptors. Within the Sphingidae species, two differing subgroups acquired hearing capability by developing alterations in their mouthparts by a distinctly independent evolutionary pathway.

Parallel evolution is exemplified in the case of the tympanal and atympanal mouthears in hawkmoths, or Sphingidae species. These insects have developed a tympanum, or eardrum, similar to humans as a means to communicate through sound. Sounds induce vibrations of a membrane that covers the tympanum, known as the tympanic membrane. These vibrations are detected by small proteins at the surface of the tympanic membrane called auditory receptors. Within the Sphingidae species, two differing subgroups acquired hearing capability by developing alterations in their mouthparts by a distinctly independent evolutionary pathway.