Sexual selection and extinction: The fate of plumage-dimorphic and plumage-monomorphic birds introduced onto islands

Correlates of the fate of 132 species of birds introduced onto one or more oceanic islands (Hawaii, Kauai, Oahu, Tahiti, La Reunion, Saint Helena, Ber muda, New Zealand and Mauritius) were examined. Introduction success rate w as less for species with sexually dichromatic plumage than for species with sexually monochromatic plumage. The diet of introduced sexually monochroma tic and dichromatic species did not differ, but a broader diet was associat ed with higher introduction success rates. In a two-way analysis, plumage a nd diet had significant effects on the introduction success rate. Species n esting primarily in bushes had higher success rates than those nesting on t he ground or in trees. Plumage type was not associated with nest location. Both plumage type and nest location had significant effects on introduction success rate in a two-way analysis. Species of introduced sexually dichrom atic birds had a lower rate of bi-parental care than did species of introdu ced sexually monochromatic birds. However, neither the number of nest-tendi ng parents nor clutch size significantly affected the rate of successful in troduction. Sexual selection drives the evolution of sexual dichromatism. T hus, our results suggest that sexual selection indirectly promotes extincti on of small, colonizing populations encountering new environmental demands by constraining ecological plasticity and evolutionary response to natural selection pressures.