scholarly journals CONVERGENT EVOLUTION OF DARWIN'S FINCHES CAUSED BY INTROGRESSIVE HYBRIDIZATION AND SELECTION

Evolution ◽  
2004 ◽  
Vol 58 (7) ◽  
pp. 1588-1599 ◽  
Author(s):  
Peter R. Grant ◽  
B. Rosemary Grant ◽  
Jeffrey A. Markert ◽  
Lukas F. Keller ◽  
K. Petren
Keyword(s):  
Convergent Evolution ◽  
Introgressive Hybridization ◽  
Darwin's Finches ◽  
Darwin’S Finches

CONVERGENT EVOLUTION OF DARWIN'S FINCHES CAUSED BY INTROGRESSIVE HYBRIDIZATION AND SELECTION

Evolution ◽  
2004 ◽  
Vol 58 (7) ◽  
pp. 1588 ◽  
Author(s):  
Peter R. Grant ◽  
B. Rosemary Grant ◽  
Jeffrey A. Markert ◽  
Lukas F. Keller ◽  
K. Petren
Keyword(s):  
Convergent Evolution ◽  
Introgressive Hybridization ◽  
Darwin's Finches ◽  
Darwin’S Finches

scholarly journals Conspecific versus heterospecific gene exchange between populations of Darwin's finches

2010 ◽  
Vol 365 (1543) ◽  
pp. 1065-1076 ◽  
Author(s):  
Peter R. Grant ◽  
B. Rosemary Grant
Keyword(s):  
Gene Flow ◽  
Introgressive Hybridization ◽  
Small Island ◽  
Gene Exchange ◽  
Darwin's Finches ◽  
Galapagos Archipelago ◽  
Darwin’S Finches ◽  
Large Populations ◽  
Geospiza Fortis ◽  
Neighbouring Island

This study addresses the extent and consequences of gene exchange between populations of Darwin's finches. Four species of ground finches ( Geospiza ) inhabit the small island of Daphne Major in the centre of the Galápagos archipelago. We undertook a study of microsatellite DNA variation at 16 loci in order to quantify gene flow within species owing to immigration and between species owing to hybridization. A combination of pedigrees of observed breeders and assignments of individuals to populations by the program S tructure enabled us to determine the frequency of gene exchange and the island of origin of immigrants in some cases. The relatively large populations of Geospiza fortis and G. scandens receive conspecific immigrants at a rate of less than one per generation. They exchange genes more frequently by rare but repeated hybridization. Effects of heterospecific gene flow from hybridization are not counteracted by lower fitness of the offspring. As a result, the standing genetic variation of the two main resident populations on Daphne Major is enhanced to a greater extent by introgressive hybridization than through breeding with conspecific immigrants. Immigrant G. fuliginosa also breeds with G. fortis . Conspecific immigration was highest in the fourth species, G. magnirostris . This species is much larger than the other three and perhaps for this reason it has not bred with any of them. The source island of most immigrants is probably the neighbouring island of Santa Cruz. Evolutionary change may be inhibited in G. magnirostris by continuing gene flow, but enhanced in G. fortis and G. scandens by introgressive hybridization.

scholarly journals Darwin's finches - an adaptive radiation constructed from ancestral genetic modules

2021 ◽  
Author(s):  
Carl-Johan Rubin ◽  
Erik D Enbody ◽  
Mariya P Dobreva ◽  
Arkhat Abzhanov ◽  
Brian W Davis ◽  
...  
Keyword(s):  
Environmental Variability ◽  
Phenotypic Diversity ◽  
Introgressive Hybridization ◽  
Ancestral Haplotype ◽  
Darwin's Finches ◽  
Haplotype Blocks ◽  
Darwin’S Finches ◽  
Adaptive Radiations ◽  
Beak Size ◽  
Genomic Regions

Recent adaptive radiations are models for investigating mechanisms contributing to the evolution of biodiversity. An unresolved question is the relative importance of new mutations, ancestral variants, and introgressive hybridization for phenotypic evolution and speciation. Here we address this issue using Darwin's finches, which vary in size from an 8g warbler finch with a pointed beak to a 40g large ground finch with a massive blunt beak. We present a highly contiguous genome assembly for one of the species and investigate the genomic architecture underlying phenotypic diversity in the entire radiation. Admixture mapping for beak and body size in the small, medium and large ground finches revealed 28 loci showing strong genetic differentiation. These loci represent ancestral haplotype blocks with origins as old as the Darwin's finch phylogeny (1-2 million years). Genes expressed in the developing beak are overrepresented in these genomic regions. Frequencies of allelic variants at the 28 loci covary with phenotypic similarities in body and beak size across the Darwin's finch phylogeny. These ancestral haplotypes constitute genetic modules for selection, and act as key determinants of the exceptional phenotypic diversity of Darwin's finches. Such ancestral haplotype blocks can be critical for how species adapt to environmental variability and change.

scholarly journals Isotopic Niche Segregation among Darwin’s Finches on Santa Cruz Island, Galápagos

Diversity ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 147
Author(s):  
Mariana Villegas ◽  
Catherine Soos ◽  
Gustavo Jiménez-Uzcátegui ◽  
Shukri Matan ◽  
Keith A. Hobson
Keyword(s):  
Three Dimensional ◽  
Sympatric Species ◽  
Isotopic Niche ◽  
Museum Specimens ◽  
Santa Cruz Island ◽  
Santa Cruz ◽  
Δ13c And Δ15n ◽  
Darwin's Finches ◽  
Darwin’S Finches ◽  
Foraging Guilds

Darwin’s finches are a classic example of adaptive radiation involving differential use of dietary resources among sympatric species. Here, we apply stable isotope (δ13C, δ15N, and δ2H) analyses of feathers to examine ecological segregation among eight Darwin’s finch species in Santa Cruz Island, Galápagos collected from live birds and museum specimens (1962–2019). We found that δ13C values were higher for the granivorous and herbivorous foraging guilds, and lower for the insectivorous finches. Values of δ15N were similar among foraging guilds but values of δ2H were higher for insectivores, followed by granivores, and lowest for herbivores. The herbivorous guild generally occupied the largest isotopic standard ellipse areas for all isotopic combinations and the insectivorous guild the smallest. Values of δ2H provided better trophic discrimination than those of δ15N possibly due to confounding influences of agricultural inputs of nitrogen. Segregation among guilds was enhanced by portraying guilds in three-dimensional isotope (δ13C, δ15N, and δ2H) space. Values of δ13C and δ15N were higher for feathers of museum specimens than for live birds. We provide evidence that Darwin’s finches on Santa Cruz Island tend to be generalists with overlapping isotopic niches and suggest that dietary overlap may also be more considerable than previously thought.

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