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4 mechanisms of speciation

allopatric speciation

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Speciation. • All species on earth thought to share single common ancestor. – That is life arose once, ca. 3.8 bya. • Speciation is the generation of species level diversity. • What processes lead to genetic differences sufficient to create a new species?
There are two general modes of speciation defined by how the gene flow between populations is interrupted. In allopatric speciation a physically barrier isolates a population, whereas sympatric speciation occur within a single geographical area and reproductive isolation arises between individuals that always have the
African pygmy kingfisher, showing coloration shared by all adults of that species to a high degree of fidelity. Comparison of allopatric, peripatric, parapatric and sympatric speciation. Freshwater angelfish, a cichlid. Rhagoletis pomonella. Gaur (Indian bison) can interbreed with domestic cattle.
How one lineage can become incompatible with its closest relative lineage is the key question of how new species are formed. Speciation can involve the gradual development of reproductive isolation, or in the case of some types of chromosomal change, be nearly instantaneous. Gradual speciation can be defined through

in Darwin's words, speciation is the “multiplication of species". • according to the BSC, speciation occurs when populations evolve reproductive isolating mechanisms. • these barriers may act to prevent fertilization – this is prezygotic isolation. • may involve changes in location or timing of breeding, or courtship.
Allopatric speciation–separate geographical areas. Peripatric speciation (tiny isolated subpopulation) Parapatric speciation–adjacent areas with some gene flow. Sympatric speciation–same area Page 21 Allopatric speciation The best understood mode of speciation is allopatric meaning “separate homelands".
ered species to be merely populations with distinguishing characteristics, the question of how they originate would be easily answered: natural selection or genetic drift can fix novel alleles or characteristics (see Chapters 10–13). But if the permanence of these distinctions depends on reproductive isolation, and.
Species and. Speciation. Species are different “kinds" of organisms. Species are the product of divergence of genetic lineages. When one genetic lineage becomes two each lineage can have an independent evolutionary future. The difference between species can be slight or dramatic. Biologists differ in their concept of
3 Jun 2008 The most common classification of modes of speciation begins with the spatial context in which divergence occurs: sympatric, parapatric or allopatric. This classification is unsatisfactory because it divides a continuum into discrete categories, concentrating attention on the extremes, and it subordinates other

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March 2018