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ENVIRONMENTAL INFLUENCES ON EPISTATIC INTERACTIONS: VIABILITIES OF CYTOCHROME C GENOTYPES IN INTERPOPULATION CROSSES
Author(s) -
Willett Christopher S.,
Burton Ronald S.
Publication year - 2003
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.0014-3820.2003.tb00240.x
Subject(s) - biology , epistasis , mitochondrial dna , genetics , copepod , hybrid , gene , reproductive isolation , genotype , allele , evolutionary biology , ecology , botany , population , demography , crustacean , sociology
.The genetic incompatibilities that underlie F 2 hybrid breakdown and reproductive isolation between al‐lopatric populations may be susceptible to environmental interactions. Here we show that epistatic interactions between cytochrome c ( CYC ) alleles and mitochondrial DNA (mtDNA) variation are dramatically influenced by environmental temperature in interpopulation hybrids of the copepod Tigriopus californicus . CYC is a nuclear‐encoded gene that functionally interacts with electron transport system (ETS) complexes composed in part of mtDNA‐encoded proteins. Previous studies have provided evidence for functional coadaptation between CYC and ETS complex IV (cytochrome c oxidase) and for cytoplasmic effects on the fitness of CYC genotype in copepod hybrids. In this study, selection on CYC genotype is shown to continue into advanced generation hybrids (F 2 ‐F 8 ) increasing the likelihood that CYC itself is involved in the interaction (and not a linked factor). Relative viabilities varied markedly between copepods raised in two different temperature/light regimes. These results suggest that both intrinsic coadaptation and extrinsic selection will influence the outcome of natural hybridizations between populations. Furthermore, the results indicate that the fitness of particular hybrid genotypes depends on additional non‐mtDNA encoded genes that interact with CYC.