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The pattern indicates repeated vicariant speciation events among these groups. [48] It is thought that rivers may play a role as the geographic barriers to Charis, [1]: 97 not unlike the river barrier hypothesis used to explain the high rates of diversity in the Amazon basin—though this hypothesis has been disputed.
There are four geographic modes of speciation in nature, based on the extent to which speciating populations are isolated from one another: allopatric, peripatric, parapatric, and sympatric. Whether genetic drift is a minor or major contributor to speciation is the subject of much ongoing discussion.
Habitat isolation is not equivalent to a geographic barrier like that of allopatric speciation. [1]: 182 Instead, it is based on genetic differences, where one species is unable to exploit a different environment, resulting from fitness advantages, fitness disadvantages, or resource competition. [1]: 182
The river seemed to be a barrier for only a few taxa, with the majority either homogeneous throughout the research area or divided into monophyletic upriver and downriver clades. Patton argues that the geographic location of these clades suggest that landform evolution is an under-appreciated factor in diversification in Amazonia. This project ...
A genetic isolate is a population of organisms that has little to no genetic mixing with other organisms of the same species due to geographic isolation or other factors that prevent reproduction. Genetic isolates form new species through an evolutionary process known as speciation. All modern species diversity is a product of genetic isolates ...
This mode of speciation has three distinguishing characteristics: 1) mating occurs non-randomly, 2) gene flow occurs unequally, and 3) populations exist in either continuous or discontinuous geographic ranges. This distribution pattern may be the result of unequal dispersal, incomplete geographical barriers, or divergent expressions of behavior ...
Speciation ultimately results due to the reproductive isolation between two populations. This can happen in a multitude of ways, a common mode of which is known as allopatric speciation. The geographic mode, where two species become physically isolated and unable to interbreed, allows for selection to act on both populations independently. Over ...
The types of barriers that can cause this isolation include: different habitats, physical barriers, and a difference in the time of sexual maturity or flowering. [ 6 ] [ 7 ] An example of the ecological or habitat differences that impede the meeting of potential pairs occurs in two fish species of the family Gasterosteidae (sticklebacks).