On the dependence of speciation rates on species abundance and characteristic population size |
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Authors: | Email author" target="_blank">Anastassia?M?MakarievaEmail author Victor?G?Gorshkov |
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Institution: | (1) Theoretical Physics Division, Petersburg Nuclear Physics Institute, St-Petersburg, 188300 Gatchina, Russia |
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Abstract: | The question of the potential importance for speciation of large/small population sizes remains open. We compare speciation
rates in twelve major taxonomic groups that differ by twenty orders of magnitude in characteristic species abundance (global
population number). It is observed that the twenty orders of magnitude’s difference in species abundances scales to less than
two orders of magnitude’s difference in speciation rates. As far as species abundance largely determines the rate of generation
of intraspecific endogenous genetic variation, the result obtained suggests that the latter rate is not a limiting factor
for speciation. Furthermore, the observed approximate constancy of speciation rates in different taxa cannot be accounted
for by assuming a neutral or nearly neutral molecular clock in subdivided populations. Neutral fixation is only relevant in
sufficiently small populations with 4N
ev < 1, which appears an unrealistic condition for many taxa of the smaller organisms. Further research is clearly needed to
reveal the mechanisms that could equate the evolutionary pace in taxa with dramatically different population sizes |
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Keywords: | Extinction fixation molecular clock neutral theory population size species duration |
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