The work was supported by the Des Lee Collaborative Vision and by two grants from the Field Research for Conservation program of the Saint Louis Zoo, as well as grants to I. Levin and P. Parker from the Whitney R. Harris World Ecology Center and the Frank M. Chapman Memorial Fund of the American Museum of Natural History. I. Levin completed this work while supported by a Dissertation Fellowship from the University of Missouri – St. Louis.
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Original Research
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Philopatry drives genetic differentiation in an island archipelago: comparative population genetics of Galapagos Nazca boobies (Sula granti) and great frigatebirds (Fregata minor)
Article first published online: 4 OCT 2012
DOI: 10.1002/ece3.386
© 2012 The Authors. Published by Blackwell Publishing Ltd. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
Additional Information
How to Cite
Ecology and Evolution 2012; 2(11): 2775–2787
Publication History
- Issue published online: 8 NOV 2012
- Article first published online: 4 OCT 2012
- Manuscript Accepted: 27 AUG 2012
- Manuscript Revised: 21 AUG 2012
- Manuscript Received: 22 JUN 2012
Funded by
- Des Lee Collaborative Vision
- Saint Louis Zoo
- Whitney R. Harris World Ecology Center
- American Museum of Natural History
- University of Missouri – St. Louis
Keywords:
- Galapagos;
- natal philopatry;
- population genetics;
- seabird
Abstract
Seabirds are considered highly mobile, able to fly great distances with few apparent barriers to dispersal. However, it is often the case that seabird populations exhibit strong population genetic structure despite their potential vagility. Here we show that Galapagos Nazca booby (Sula granti) populations are substantially differentiated, even within the small geographic scale of this archipelago. On the other hand, Galapagos great frigatebird (Fregata minor) populations do not show any genetic structure. We characterized the genetic differentiation by sampling five colonies of both species in the Galapagos archipelago and analyzing eight microsatellite loci and three mitochondrial genes. Using an F-statistic approach on the multilocus data, we found significant differentiation between nearly all island pairs of Nazca booby populations and a Bayesian clustering analysis provided support for three distinct genetic clusters. Mitochondrial DNA showed less differentiation of Nazca booby colonies; only Nazca boobies from the island of Darwin were significantly differentiated from individuals throughout the rest of the archipelago. Great frigatebird populations showed little to no evidence for genetic differentiation at the same scale. Only two island pairs (Darwin – Wolf, N. Seymour – Wolf) were significantly differentiated using the multilocus data, and only two island pairs had statistically significant φST values (N. Seymour – Darwin, N. Seymour – Wolf) according to the mitochondrial data. There was no significant pattern of isolation by distance for either species calculated using both markers. Seven of the ten Nazca booby migration rates calculated between island pairs were in the south or southeast to north or northwest direction. The population differentiation found among Galapagos Nazca booby colonies, but not great frigatebird colonies, is most likely due to differences in natal and breeding philopatry.