MHC Variation in the Endangered Gila Topminnow

Sequence variation at a major histocompatibility complex (MHC) gene, assumed to be involved in parasite and pathogen resistance, was examined in the endangered Gila topminnow (Poeciliopis o. occidentalis), from the four watersheds where they remain in the United States. This is the first estimate of...

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Bibliographic Details
Published in:Evolution 1998-02, Vol.52 (1), p.194-199
Main Authors: Hedrick, Philip W., Parker, Karen M.
Format: Article
Language:English
Subjects:
Alleles
Amino acids
Bottleneck
conservation
Cyprinodontidae
Endangered & extinct species
Endangered species
evolutionarily significant unit
Evolutionary genetics
Fish
Freshwater
Freshwater fishes
Genetic loci
Genetic variation
Genetics
Heterozygotes
Human genetics
Killifishes
Major histocompatibility complex
parasite resistance
Parasites
Poeciliopis occidentalis occidentalis
polymorphism
Population genetics
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Summary:Sequence variation at a major histocompatibility complex (MHC) gene, assumed to be involved in parasite and pathogen resistance, was examined in the endangered Gila topminnow (Poeciliopis o. occidentalis), from the four watersheds where they remain in the United States. This is the first estimate of variation in MHC genes in natural populations of an endangered species. The population that has experienced the most bottlenecks historically was monomorphic for MHC variation. Another population, which earlier had been found to be the only population polymorphic for allozymes, had five MHC alleles, four different from those found in the other populations. Overall, nine different alleles were found. The four populations were highly divergent at MHC with four of the six population pairs not sharing any alleles. However, the magnitude of differentiation between populations on the amino-acid level varied fivefold for the populations that shared no alleles. Using single-stranded conformational polymorphism (SSCP), these alleles segregated consistently with Mendelian expectations in families. Because of the high genetic differentiation between these populations for a potentially adaptive gene, we recommend that the four watersheds be examined further for separate conservation and management.
ISSN:0014-3820
1558-5646
DOI:10.1111/j.1558-5646.1998.tb05152.x