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DEVELOPMENT OF THE HYBRID SWARM BETWEEN PECOS PUPFISH (CYPRINODONTIDAE: CYPRINODON PECOSENSIS ) AND SHEEPSHEAD MINNOW ( CYPRINODON VARIEGATUS ): A PERSPECTIVE FROM ALLOZYMES AND mtDNA
Author(s) -
Childs Michael R.,
Echelle Anthony A.,
Dowling Thomas E.
Publication year - 1996
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.1558-5646.1996.tb03588.x
Subject(s) - biology , introgression , gene flow , mitochondrial dna , zoology , conservation genetics , evolutionary biology , ecology , allele , genetic variation , genetics , microsatellite , gene
A comparison of allozyme and mtDNA frequencies was used for insight into a situation in the Pecos River, Texas where contact between the endemic pupfish ( Cyprinodon pecosensis ) and an introduced congener ( C. variegatus ) has resulted in rapid, geographically extensive genetic introgression. Temporal changes in mean frequencies of diagnostic allozyme markers indicate that the clinal pattern of introduced genetic material (Echelle and Connor 1989) is slowly decreasing in amplitude. Significant rank concordance in diagnostic allele frequencies among sites and across sampling years indicates directional influences upon temporal allele frequency change. These observations are consistent with the theory of gene flow in neutral clines. Levels of introgression indicated by each of four allozyme loci and mtDNA were roughly equivalent. The early history of the hybrid swarm is explained by genetic swamping, possibly mediated by selection for C. variegatus or C. variegatus × C. pecosensis , at a time when the normally abundant endemic species had been catastrophically depleted. High frequencies of an introduced GPI‐A allele in all samples of intergrades suggests that the introduced genome originated with a single founding event.