Darwin's finches: Population variation and sympatric speciation

Grant, B. Rosemary; Grant, Peter R.

doi:10.1073/pnas.76.5.2359

Cited by 71 publications

(44 citation statements)

References 18 publications

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“…Strong assortative mating, in turn, could power intermorph reproductive isolation and genetic divergence (Huber et al 2007). A parallel argument had been made previously for the Geospiza conirostris population on Isla Genovesa (Grant & Grant 1979), which in initial years of study showed vocal morphs and some bimodality in morphology. However, initial observed patterns of assortative mating broke down over subsequent years (Grant & Grant 1989).…”

Section: Discrimination Of Sympatric Morphs J Podos 1035mentioning

confidence: 69%

Acoustic discrimination of sympatric morphs in Darwin's finches: a behavioural mechanism for assortative mating?

Podos

2010

Phil. Trans. R. Soc. B

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Populations with multiple morphological or behavioural types provide unique opportunities for studying the causes and consequences of evolutionary diversification. A population of the medium ground finch (Geospiza fortis) at El Garrapatero on Santa Cruz Island, Galápagos, features two beak size morphs. These morphs produce acoustically distinctive songs, are subject to disruptive selection and mate assortatively by morph. The main goal of the present study was to assess whether finches from this population are able to use song as a cue for morph discrimination. A secondary goal of this study was to evaluate whether birds from this population discriminate songs of their own locality versus another St Cruz locality, Borrero Bay, approximately 24 km to the NW. I presented territorial males with playback of songs of their own morph, of the other morph, and of males from Borrero Bay. Males responded more strongly to same-morph than to other-morph playbacks, showing significantly shorter latencies to flight, higher flight rates and closer approaches to the playback speaker. By contrast, I found only minor effects of locality on responsiveness. Evidence for morph discrimination via acoustic cues supports the hypothesis that song can serve as a behavioural mechanism for assortative mating and sympatric evolutionary divergence.

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Section: Discrimination Of Sympatric Morphs J Podos 1035mentioning

confidence: 69%

Acoustic discrimination of sympatric morphs in Darwin's finches: a behavioural mechanism for assortative mating?

Podos

2010

Phil. Trans. R. Soc. B

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“…Gill (1973) has stressed the rarity with which avian microgeographic variation occurs on islands. Grenada may be one of the smallest islands with a polymorphic bird species (but see Grant and Grant, 1979). …”

Section: Discussionmentioning

confidence: 99%

AN ANALYSIS OF A MORPH RATIO CLINE IN THE BANANAQUIT (COEREBA FLAVEOLA) ON GRENADA, WEST INDIES

Wunderle

1981

Evolution

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“…In one, Grant & Grant (1979) described a population of Geospiza conirostris (large cactus ground finch) on Genovesa Island that was composed of two male types singing different songs and having different beak sizes and foraging habits. These initial distinctions subsequently broke down (Grant & Grant 1989), and no further attention has been directed towards this population.…”

Section: Introductionmentioning

confidence: 99%

Divergence with gene flow as facilitated by ecological differences: within-island variation in Darwin's finches

León

Bermingham

Podos

et al. 2010

Phil. Trans. R. Soc. B

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Divergence and speciation can sometimes proceed in the face of, and even be enhanced by, ongoing gene flow. We here study divergence with gene flow in Darwin's finches, focusing on the role of ecological/adaptive differences in maintaining/promoting divergence and reproductive isolation. To this end, we survey allelic variation at 10 microsatellite loci for 989 medium ground finches (Geospiza fortis) on Santa Cruz Island, Galápagos. We find only small genetic differences among G. fortis from different sites. We instead find noteworthy genetic differences associated with beak. Moreover, G. fortis at the site with the greatest divergence in beak size also showed the greatest divergence at neutral markers; i.e. the lowest gene flow. Finally, morphological and genetic differentiation between the G. fortis beak-size morphs was intermediate to that between G. fortis and its smaller (Geospiza fuliginosa) and larger (Geospiza magnirostris) congeners. We conclude that ecological differences associated with beak size (i.e. foraging) influence patterns of gene flow within G. fortis on a single island, providing additional support for ecological speciation in the face of gene flow. Patterns of genetic similarity within and between species also suggest that interspecific hybridization might contribute to the formation of beak-size morphs within G. fortis.

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Darwin's finches: Population variation and sympatric speciation

Abstract: The classical model of the adaptive radiation of Darwin's finches is one of repeated speciation in allopatry. Evidence

Cited by 71 publications

References 18 publications

Acoustic discrimination of sympatric morphs in Darwin's finches: a behavioural mechanism for assortative mating?

Acoustic discrimination of sympatric morphs in Darwin's finches: a behavioural mechanism for assortative mating?

AN ANALYSIS OF A MORPH RATIO CLINE IN THE BANANAQUIT (COEREBA FLAVEOLA) ON GRENADA, WEST INDIES

Divergence with gene flow as facilitated by ecological differences: within-island variation in Darwin's finches

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