BALANCING SELECTION IN A DESERT STREAM-DWELLING FISH, POECILIOPSIS MONACHA

Robert C Vrijenhoek; Edward Pfeiler; Jeffrey D Wetherington

doi:10.1111/j.1558-5646.1992.tb01159.x

BALANCING SELECTION IN A DESERT STREAM-DWELLING FISH, POECILIOPSIS MONACHA

Evolution. 1992 Dec;46(6):1642-1657. doi: 10.1111/j.1558-5646.1992.tb01159.x.

Authors

Robert C Vrijenhoek¹, Edward Pfeiler², Jeffrey D Wetherington^{1

3}

Affiliations

¹ Center for Theoretical and Applied Genetics, Rutgers University, New Brunswick, NJ, 08903-0231, USA.
² Departamento de Ciencias Marinas, Instituto Tecnológico y de Estudios Superiores de Monterrey, Guaymas, Sonora, 85400, MEXICO.
³ Agricultural Products Division, Dupont Company, Wilmington, DE, 19880-0402, USA.

PMID: 28567757
DOI: 10.1111/j.1558-5646.1992.tb01159.x

Abstract

The desert stream-dwelling fish Poeciliopsis monacha is exposed to extreme seasonal and spatial variation in physical stresses. We examined four diallelic gene loci (Ldh-1, Idh-2, Pgd, and Ck-A) in P. monacha and tested whether genotypes were associated with differential survival of individuals exposed to acute stress. For each locus, the common allele was associated with higher survival during heat and hypoxic stress, whereas the alternate allele was associated with higher survival during cold stress. In most cases, survival of heterozygotes was intermediate and they exhibited less variance in survival than corresponding homozygotes. Identification of substantial linkage disequilibrium in these fish confounds our ability to discern whether the allozymes are the direct targets of selection, or if they just mark chromosomal regions that contain the true modifiers of survival. Nevertheless, the present results clearly identified balancing processes that can serve to stabilize genetic polymorphism in this species.

Keywords: Allozymes; F-statistics; balancing selection; heterogeneous environment; linkage disequilibrium.