John C. Avise A. Beaumont Kim T. Scribner 1994 <p>Experimental laboratory crosses and population experiments reveal significant differences in individual life-history traits and population demography between two related species of mosquitofish, <i>Gambusia affinis</i> and <i>G. holbrooki</i>. With respect to life-history traits, progeny from <i>G. holbrooki</i> exhibit larger size at birth and earlier age at sexual maturity than do progeny from <i>G. affinis</i> parents. With respect to demography, populations of <i>G. holbrooki</i> exhibit higher recruitment and carrying capacity and loser overwinter mortality than do populations of <i>G. affinis</i>. These differences help t explain the dramatic changes in cytonuclear genotype frequency observed in replicated experimental hybrid populations of <i>Gambusia</i> monitored over 52 weeks. These experimental results are interpreted in the context of introgression patterns previously studied indirectly from distributions of cytonuclear genotypes in a natural mosquitofish hybrid zone.</p> application/pdf en Chapman and Hall Demographic and life history characteristics influence the cytonuclear composition of mosquitofish populations chapter