GENETIC CORRELATES OF FITNESS IN THE GREEN TREEFROG, HYLA-CINEREA

Effects of an individual's genotype on its fitness may vary with envir onmental conditions or across time. Green treefrogs, Hyla cinerea, wer e collected from a single pond for three consecutive summers (1989-199 1) and identified as belonging to one of four groups: calling males, m ated males, mated females, and juvenile metamorphs. We used eight poly morphic loci to examine differences among groups and across years. Het erozygosity at the isocitrate dehydrogenase-2 (IDH-2) locus was associ ated with enhanced overwinter survival of juveniles and male mating su ccess; however, the relationship was not consistent across time. The a ssociation at the IDH-2 locus may be weak or the result of an interact ion and, therefore, seen only under certain conditions. A shift in all elic and genotypic frequencies corresponded to changes in heterozygosi ty. Although the exact cause of the association is not known, this stu dy illustrates the temporally dynamic nature of the genetics of natura l populations. Multilocus heterozygosity did not appear to be a good i ndicator of survival or mating success in N. cinerea.