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1 June 2005 SPECIATION THROUGH COMPETITION: A CRITICAL REVIEW
Jitka Polechová, Nicholas H. Barton
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Abstract

We examined causes of speciation in asexual populations in both sympatry and parapatry, providing an alternative explanation for the speciation patterns reported by Dieckmann and Doebeli (1999) and Doebeli and Dieckmann (2003). Both in sympatry and parapatry, they find that speciation occurs relatively easily. We reveal that in the sympatric clonal model, the equilibrium distribution is continuous and the disruptive selection driving evolution of discrete clusters is only transient. Hence, if discrete phenotypes are to remain stable in the sympatric sexual model, there should be some source of nontransient disruptive selection that will drive evolution of assortment. We analyze sexually reproducing populations using the Bulmer's infinitesimal model and show that cost-free assortment alone leads to speciation and disruptive selection only arises when the optimal distribution cannot be matched—in this example, because the phenotypic range is limited. In addition, Doebeli and Dieckmann's analyses assumed a high genetic variance and a high mutation rate. Thus, these theoretical models do not support the conclusion that sympatric speciation is a likely outcome of competition for resources. In their parapatric model (Doebeli and Dieckmann 2003), clustering into distinct phenotypes is driven by edge effects, rather than by frequency-dependent competition.

Jitka Polechová and Nicholas H. Barton "SPECIATION THROUGH COMPETITION: A CRITICAL REVIEW," Evolution 59(6), 1194-1210, (1 June 2005). https://doi.org/10.1554/04-691
Received: 16 November 2004; Accepted: 22 March 2005; Published: 1 June 2005
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KEYWORDS
Asexual populations
assortative mating
frequency-dependent selection
overdominance
parapatry
sympatry
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