Why is there so much genetic variation for wing dimorphism? |
| |
Authors: | Derek A Roff |
| |
Institution: | (1) Department of Biology, McGill University, 1205 Dr Penfield Ave., H3A 1B1 Montreal, Canada |
| |
Abstract: | Wing dimorphism appears in general to be determined either by a single locus, 2 allele system in which brachyptery is dominant,
or by the additive action of numerous loci. In the latter case studies indicate that the heritability is typically quite large.
It is generally postulated that wing dimorphism is under strong selection: why then is genetic variation not eroded? In this
paper I consider three possible explanations. First, genetic variation may not be exposed to selection because environmental
heterogeneity effectively makes heritability zero. Because wing dimorphisms are known to evolve it seems unlikely that this
is the primary factor. Second, directional selection on a threshold trait may push the population almost to monomorphism but
erodes genetic variance at a very slow rate. This mechanism cannot preserve variation but makes it possible for other factors
to more easily maintain variability. Finally, I demonstrate that in a heterogeneous environment spatio-temporal variation
in fitness will itself maintain a genetic polymorphism for wing dimorphism.
This paper is dedicated to Professor Sinzo Masaki, whose work on the evolution of wing dimorphism and diapause has been so
important to our understanding of the evolution of dimorphic variation. |
| |
Keywords: | wing dimorphism heritability genetic variation heterogeneity |
本文献已被 SpringerLink 等数据库收录! |
|