The fate of balanced, phenotypic polymorphisms in fragmented metapopulations

Craze, Paul G (2009) The fate of balanced, phenotypic polymorphisms in fragmented metapopulations. Journal of Evolutionary Biology, 22 (7). 1556 - 1561. ISSN 1420-9101

Full text not available from this repository.


In large populations, genetically distinct phenotypic morphs can be maintained in equilibrium (at a 1 : 1 ratio in the simplest case) by frequency-dependent selection, as shown by Sewall Wright. The consequences of population fragmentation on this equilibrium are not widely appreciated. Here, I use a simple computational model to emphasize that severe fragmentation biases the morph ratio towards the homozygous recessive genotype through drift in very small populations favouring the more common recessive allele. This model generalizes those developed elsewhere for heterostylous plants and major histocompatibility complex alleles, emphasizes one particular outcome and avoids the restricting assumptions of more analytical models. There are important implications for both fundamental evolutionary biology and conservation genetics. I illustrate this with a range of examples but refer particularly to shell polymorphism in snails. These examples show how habitat fragmentation could have a direct and often unappreciated effect on species at the level of their population genetics.

Item Type: Article
Keywords: computational modelling; frequency-dependent selection; genetic drift; recessive alleles
Schools and Departments: School of Life Sciences > Biology and Environmental Science
Depositing User: Paul Craze
Date Deposited: 06 Feb 2012 18:42
Last Modified: 24 Jul 2012 11:07
📧 Request an update