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BIOCHEMICAL GENETICS OF SUNFISH. I. GEOGRAPHIC VARIATION AND SUBSPECIFIC INTERGRADATION IN THE BLUEGILL, LEPOMIS MACROCHIRUS
Author(s) -
Avise John C.,
Smith Michael H.
Publication year - 1974
Publication title -
evolution
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.84
H-Index - 199
eISSN - 1558-5646
pISSN - 0014-3820
DOI - 10.1111/j.1558-5646.1974.tb00725.x
Subject(s) - south carolina , lepomis macrochirus , biology , ecology , library science , genealogy , fishery , fish <actinopterygii> , computer science , history , political science , public administration
Zones of secondary contact between allopatrically evolved populations have long been of particular interest to students of evolution. Former isolates often have not evolved fully efficient isolating mechanisms before rejoining and hybridization results. With the acquisition of electrophoretic techniques, the genetic aspects of natural hybridization can be examined in detail. Patterns of introgression of alleles are expected to differ depending largely on the extent to which the populations' gene pools have diverged and on the intensity of selection against "the infiltration of genes from one balanced complex into another" (Mayr, 1963). Theoretically, situations should be found representing a continuum from hybridization with no introgression, to free gene exchange resulting in the eventual fusion of gene pools. Genic and/or chromosomal imbalance may lead to hybrid sterility and restrict allelic exchange to the F 1 generation. Patton et al. (1972) found no evidence of genic introgression between two hybridizing species of gophers in Arizona. Lowered fitness of certain recombinant types may greatly limit allelic introgression. Hall and Selander (1973) found evidence for a very low level of introgression between karyotypically distinct "F6" and "PI" populations formerly placed in the lizard species Sceloporus grammicus. Selander et al. (1969) and Hunt and Selander (1973), working with semispecies of house mice, found steep gradients of transition in genic character across an area of contact, and differential extents of introgression of alleles among loci. They