Parallel adaptive patterns of allozyme and inversion polymorphisms on an ecological gradient

Abstract

Trimerotropis pallidipennis is an American grasshopper whose South American populations are polymorphic for pericentric inversions. The frequencies of some of these rearrangements are correlated with geographical and climatic variables, following similar patterns among different ecological gradients. Hence, this species constitutes a promising model in which the evolutionary significance of inversion systems can be analysed as possible sources of coadapted groups of linked genes. Six samples collected along an altitudinal gradient were assayed jointly for genetic and chromosomal variation. Interestingly, the phenograms constructed with Nei’s genetic distances obtained from allozyme and chromosome data were almost identical. This result is produced mainly by esterase loci variation, probably as a consequence of linkage disequilibrium. The evolutionary significance of this association is briefly discussed.