Medium Ground-Finch (Geospiza fortis)

2020 ◽  
Author(s):  
Alvaro Jaramillo ◽  
David Christie
Keyword(s):  
Geospiza Fortis

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

2010 ◽  
Vol 365 (1543) ◽  
pp. 1031-1039 ◽  
Author(s):  
Jeffrey Podos
Keyword(s):  
Assortative Mating ◽  
Disruptive Selection ◽  
Evolutionary Divergence ◽  
Santa Cruz Island ◽  
Evolutionary Diversification ◽  
Acoustic Discrimination ◽  
Behavioural Types ◽  
Geospiza Fortis ◽  
Beak Size ◽  
Behavioural Mechanism

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.

scholarly journals INBREEDING IN DARWIN'S MEDIUM GROUND FINCHES (GEOSPIZA FORTIS )

Evolution ◽  
1989 ◽  
Vol 43 (6) ◽  
pp. 1273-1284 ◽  
Author(s):  
H. Lisle Gibbs ◽  
Peter R. Grant
Keyword(s):  
Geospiza Fortis

scholarly journals Inbreeding in Darwin's Medium Ground Finches (Geospiza fortis)

Evolution ◽  
1989 ◽  
Vol 43 (6) ◽  
pp. 1273 ◽  
Author(s):  
H. Lisle Gibbs ◽  
Peter R. Grant
Keyword(s):  
Geospiza Fortis

scholarly journals Morphological ghosts of introgression in Darwin’s finch populations

2021 ◽  
Vol 118 (31) ◽  
pp. e2107434118
Author(s):  
Peter R. Grant ◽  
B. Rosemary Grant
Keyword(s):  
Evolutionary History ◽  
Genomic Data ◽  
Evolutionary Divergence ◽  
Gene Exchange ◽  
Future Evolution ◽  
Large Form ◽  
Large Samples ◽  
As Species ◽  
History Of ◽  
Geospiza Fortis

Many species of plants, animals, and microorganisms exchange genes well after the point of evolutionary divergence at which taxonomists recognize them as species. Genomes contain signatures of past gene exchange and, in some cases, they reveal a legacy of lineages that no longer exist. But genomic data are not available for many organisms, and particularly problematic for reconstructing and interpreting evolutionary history are communities that have been depleted by extinctions. For these, morphology may substitute for genes, as exemplified by the history of Darwin’s finches on the Galápagos islands of Floreana and San Cristóbal. Darwin and companions collected seven specimens of a uniquely large form of Geospiza magnirostris in 1835. The populations became extinct in the next few decades, partly due to destruction of Opuntia cactus by introduced goats, whereas Geospiza fortis has persisted to the present. We used measurements of large samples of G. fortis collected for museums in the period 1891 to 1906 to test for unusually large variances and skewed distributions of beak and body size resulting from introgression. We found strong evidence of hybridization on Floreana but not on San Cristóbal. The skew is in the direction of the absent G. magnirostris. We estimate introgression influenced 6% of the frequency distribution that was eroded by selection after G. magnirostris became extinct on these islands. The genetic residuum of an extinct species in an extant one has implications for its future evolution, as well as for a conservation program of reintroductions in extinction-depleted communities.

scholarly journals Ontogeny of the cranial skeleton in a Darwin’s finch (Geospiza fortis)

2011 ◽  
Vol 219 (2) ◽  
pp. 115-131 ◽  
Author(s):  
Annelies Genbrugge ◽  
Anne-Sophie Heyde ◽  
Dominique Adriaens ◽  
Matthieu Boone ◽  
Luc Van Hoorebeke ◽  
...  
Keyword(s):  
Geospiza Fortis

scholarly journals Neutral locus heterozygosity, inbreeding, and survival in Darwin's ground finches (Geospiza fortis and G. scandens)

Heredity ◽  
2004 ◽  
Vol 92 (4) ◽  
pp. 306-315 ◽  
Author(s):  
J A Markert ◽  
P R Grant ◽  
B R Grant ◽  
L F Keller ◽  
J L Coombs ◽  
...  
Keyword(s):  
Neutral Locus ◽  
Geospiza Fortis

scholarly journals Possible human impacts on adaptive radiation: beak size bimodality in Darwin's finches

2006 ◽  
Vol 273 (1596) ◽  
pp. 1887-1894 ◽  
Author(s):  
Andrew P Hendry ◽  
Peter R Grant ◽  
B Rosemary Grant ◽  
Hugh A Ford ◽  
Mark J Brewer ◽  
...  
Keyword(s):  
Adaptive Radiation ◽  
Human Activities ◽  
Human Impacts ◽  
Adaptive Landscape ◽  
Hybrid Fitness ◽  
Evolutionary Diversification ◽  
Adaptive Landscapes ◽  
Adaptive Radiations ◽  
Geospiza Fortis ◽  
Beak Size

Adaptive radiation is facilitated by a rugged adaptive landscape, where fitness peaks correspond to trait values that enhance the use of distinct resources. Different species are thought to occupy the different peaks, with hybrids falling into low-fitness valleys between them. We hypothesize that human activities can smooth adaptive landscapes, increase hybrid fitness and hamper evolutionary diversification. We investigated this possibility by analysing beak size data for 1755 Geospiza fortis measured between 1964 and 2005 on the island of Santa Cruz, Galápagos. Some populations of this species can display a resource-based bimodality in beak size, which mirrors the greater beak size differences among species. We first show that an historically bimodal population at one site, Academy Bay, has lost this property in concert with a marked increase in local human population density. We next show that a nearby site with lower human impacts, El Garrapatero, currently manifests strong bimodality. This comparison suggests that bimodality can persist when human densities are low (Academy Bay in the past, El Garrapatero in the present), but not when they are high (Academy Bay in the present). Human activities may negatively impact diversification in ‘young’ adaptive radiations, perhaps by altering adaptive landscapes.

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