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Large body size in an island‐dwelling bird: a microevolutionary analysis
Author(s) -
FRENTIU F. D.,
CLEGG S. M.,
BLOWS M. W.,
OWENS I. P. F.
Publication year - 2007
Publication title -
journal of evolutionary biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.289
H-Index - 128
eISSN - 1420-9101
pISSN - 1010-061X
DOI - 10.1111/j.1420-9101.2006.01242.x
Subject(s) - passerine , biology , selection (genetic algorithm) , directional selection , evolutionary biology , stabilizing selection , microevolution , ecology , population , zoology , genetic variation , demography , genetics , artificial intelligence , sociology , computer science , gene
Island races of passerine birds display repeated evolution towards larger body size compared with their continental ancestors. The Capricorn silvereye ( Zosterops lateralis chlorocephalus ) has become up to six phenotypic standard deviations bigger in several morphological measures since colonization of an island approximately 4000 years ago. We estimated the genetic variance–covariance ( G) matrix using full‐sib and ‘animal model’ analyses, and selection gradients, for six morphological traits under field conditions in three consecutive cohorts of nestlings. Significant levels of genetic variance were found for all traits. Significant directional selection was detected for wing and tail lengths in one year and quadratic selection on culmen depth in another year. Although selection gradients on many traits were negative, the predicted evolutionary response to selection of these traits for all cohorts was uniformly positive. These results indicate that the G matrix and predicted evolutionary responses are consistent with those of a population evolving in the manner observed in the island passerine trend, that is, towards larger body size.