Inversion polymorphisms in Trimerotropis pallidipennis (0 rt ho pte ra): clinal variation along an altitudinal gradient

CONFALONIERI, V. ; COLOMBO, P.C.

HEREDITY

NATURE PUBLISHING GROUP

Lugar: Londres; Año: 1989 vol. 62 p. 107 - 112

0018-067X

Six populations of Trimerotropis pallidipennis located along an Altitudinal gradient in the Antinaco—Los Colorados valley (La Rioja, Argentina), were cytologically analysed. The male karyotype consists of 23 chromosomes (22+XO) with three long pairs submetacentric, the X-chromosome metacentric and the remaining ones basically acrocentric. Populations from La Rioja were polymorphic for seven pericentric inversions. Correlations between chromosome frequencies and altitude were statistically tested. In most cases, variables were either positively or negatively related in a significant fashion. As a consequence, mean populational heterozygosis (measured as the mean number of heteromorphic bivalents per individual per population) was also Positively correlated with altitude. These results suggest that altitude (or other correlated environmental variable) may exert a differential selective pressure on coadapted gene blocks in the mutually inverted sequences. The possible relation of these results with the centralmarginal model is discussed.