Article Summary–Hybrid Fitness

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Article Summary–Hybrid Fitness

Grant, P.R. 1994. Population variation and hybridization--comparison of finches from 2 archipelagos. Evolutionary Ecology 8: 598-617.

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.

1. Explore why there is this difference between the avifaunas of the two archipelagos. Do the time scales for evolutionary change differ between the two archipelagos?
To create paragraphs in your essay response, type at the beginning of the paragraph, and at the end.

2. From your knowledge of the mechanisms of microevolutionary change, could you predict what kind of an influence a less seasonal and floristically rich habitat should have on speciation and variability of traits?
To create paragraphs in your essay response, type at the beginning of the paragraph, and at the end.

3. What could be the reason that there are no intermediate phenotypes, at least with regard to beak morphologies on the Hawaiian islands? Think about the ecological niches of the parental species.
To create paragraphs in your essay response, type at the beginning of the paragraph, and at the end.




1.	Explore why there is this difference between the avifaunas of the two archipelagos. Do the time scales for evolutionary change differ between the two archipelagos? To create paragraphs in your essay response, type <p> at the beginning of the paragraph, and </p> at the end.



2.	From your knowledge of the mechanisms of microevolutionary change, could you predict what kind of an influence a less seasonal and floristically rich habitat should have on speciation and variability of traits? To create paragraphs in your essay response, type <p> at the beginning of the paragraph, and </p> at the end.



3.	What could be the reason that there are no intermediate phenotypes, at least with regard to beak morphologies on the Hawaiian islands? Think about the ecological niches of the parental species. To create paragraphs in your essay response, type <p> at the beginning of the paragraph, and </p> at the end.

Chapter 15: Literature: Speciation, Hybridization, and Ecotones

Article Summary–Hybrid Fitness