A CENTURY OF GENETIC CHANGE AND METAPOPULATION DYNAMICS IN THE GALÁPAGOS WARBLER FINCHES (CERTHIDEA)

• Published in: Evolution 2011-11, Vol.65 (11), p.3148-3161
• Main Authors: Farrington, Heather L., Petren, Kenneth
• Format: Article
• Language: English
• Subjects: Animal Migration; Animals; Biological variation; Birds; Conservation biology; Ecuador; Evolution; Evolution, Molecular; Evolutionary biology; Evolutionary genetics; Finches; Finches - genetics; Gene flow; Gene Frequency; Genetic diversity; Genetic loci; genetic monitoring; Genetic Variation; Genetics, Population; Human migration; Immigration; Microsatellite Repeats - genetics; museum specimens; Museums; natural history collections; Population Dynamics; Population genetics; Population size; Principal Component Analysis; SSR; Warblers
• ISSN: 0014-3820; 1558-5646
• DOI: 10.1111/j.1558-5646.2011.01385.x

Populations that are connected by immigrants play an important role in evolutionary and conservation biology, yet we have little direct evidence of how such metapopulations change genetically over evolutionary time. We compared historic (1894-1906) to modern (1988-2006) genetic variation in 11 populations of warbler finches at 14 microsatellite loci. Although several lines of evidence suggest that Darwin's finches may be in decline, we found that the genetic diversity of warbler finches has not generally declined, and broad-scale patterns of variation remained similar over time. Contrary to expectations, inferred population sizes have generally increased over time (6-8%) as have immigration rates (8-16%), which may reflect a recent increase in the frequency and intensity of El Nino events. Individual island populations showed significant declines (18-19%) and also substantial gains (18-20%) in allelic richness over time. Changes in genetic diversity were correlated with changes in immigration rates, but did not correspond to population size or human disturbance. These results reflect the expected stabilizing properties of whole metapopulations over time. However, the dramatic and unpredictable changes observed in individual populations during this short time interval suggests that care should be taken when monitoring individual population fragments with snapshots of genetic variation.