THE NICHE-WIDTH VARIATION HYPOTHESIS RECONFIRMED - VALIDATION BY GENETIC DIVERSITY IN THE SESSILE INTERTIDAL CIRRIPEDES CHTHAMALUS-STELLATUS AND EURAPHIA-DEPRESSA (CRUSTACEA, CHTHAMALIDAE)

Genetic diversity in a pair of cirripede species, based on electrophor etic analysis of 25 gene loci, is higher for Chthamalus stellatus, the species with a broader biogeographical distribution, and hence, with a broader ecological niche, than that of Euraphia depressa. Comparing the genetic diversity within E. depressa we again report a higher gene tic diversity among the specimens exposed to solar radiation (living i n the wider ecological niche) versus the specimens confined to the she ltered dark environments in caves or under boulders. The indices of ge netic diversity used in this study are polymorphism, heterozygosity, m ean number of alleles per locus and gene diversity. We conclude that t he niche-width variation hypothesis has been confirmed in this pair of species: genetic diversity is positively correlated with niche breadt h.