Correlations among size-related traits affected by chromosome inversions in Drosophila buzzatii: the comparison within and across environments.

Genetic variation in correlations among size-related traits of head, thorax, and wings was examined in Drosophila buzzatii, by comparing the pattern of the Phenotypic Correlation Matrix (Rp) between inversion karyotypes of the second chromosome. No similarity in Rp was observed between some karyotypes in a natural population. The pattern of Rp in wild-reared heterokaryotypes, but not in homokaryotypes, was similar to the whole population represented by laboratory-reared flies. While phenotypic correlations in wild-reared flies were found to be larger than in laboratory-reared flies, similarity in the pattern of Rp was very high for one homokaryotype reared in both environments: the relatively homogeneous lab environment and the more variable field environment. While no such a similarity across environments was detected between different karyotypes, the pattern of Rp was similar for a same homokaryotype in different populations. Thus, the lack of karyotypic similarity in Rp is, at least partially, genetic. These results indicate that chromosomal inversions are factors affecting genetic correlations among traits known to be phenotypically correlated with adult fitness components in this species.