Chapter 15: Literature: Speciation, Hybridization, and Ecotones
Article SummaryHybrid Fitness
The studies by Rosemary and Peter Grant are among the very few to document fitness effects of hybrids in wild animal populations. How general are these results, or more specifically, do other birds on islands also hybridize as frequently? If so, does this result in the high variability of traits like beak depth which is characteristic for Darwin's finches?
Peter Grant analyzed this question in more than 500 museum specimens of honeycreeper-finches from the Hawaiian islands, which he then compared to six Darwin's ground finch species. Interestingly, the Hawaiian finches were not as variable as the Darwin's finches. Even potentially hybridizing species were not more variable than allopatric species. Peter Grant concluded that this leaves very little evidence for hybridization within at least the last 100 years or so--this is as far back as the museum collections go.