Conservation Genetics

, Volume 17, Issue 4, pp 903–920 | Cite as

Exploring the legacy of goat grazing: signatures of habitat fragmentation on genetic patterns of endemic weevil populations in Northern Isabela Island, Galápagos (Ecuador)

  • Andrea S. Sequeira
  • Courtney C. Stepien
  • Christina T. Tran
  • Austin Stuckert
  • Lázaro Roque Albelo
  • Weixia Guo
Research Article


Together with reduction in habitat area and quality, reduction in habitat connectivity is one of the major factors influencing species’ persistence in fragmented landscapes. We explore the consequences of recent habitat fragmentation on volcanoes across Isabela Island, Galápagos by analyzing genetic patterns of populations of endemic weevils whose host plants have been depleted by indiscriminate goat grazing. We predicted that if grazing on the weevils’ host plants has caused habitat fragmentation on the weevils populations themselves, then the effects on the genetic architecture of populations should be more severe on Galapaganus conwayensis populations from volcanoes on Northern Isabela than on those from Santa Cruz or Pinta islands where vegetation destruction was not as extensive. We used mitochondrial sequences to reveal historical colonization patterns and microsatellite variation to understand more contemporary genetic changes. We found significantly lower microsatellite genetic diversity and population size within localities and increased genetic differentiation at a small geographic scale with a stronger isolation by distance pattern and larger numbers of genetic clusters on Isabela. In the absence of long-standing mitochondrial structure within each volcano, we interpret the microsatellite results as suggesting that recent host plant habitat fragmentation may indeed influence the genetic patterns of plant feeding insects and highlight the importance of controlling the spread of introduced herbivores in the Galápagos Islands.


Galapaganus conwayensis Microsatellite loci Mitochondrial sequences Within-population variation Population differentiation Genetic clusters 



Scientific research permits for all collecting trips were obtained from the Parque Nacional Galápagos through the Department of Terrestrial Invertebrates at the Charles Darwin Research Station (Santa Cruz Island). We gratefully acknowledge L. Cruz (and the crew from “El Pirata”), T. Dittmann, H. Herrera, P. Lincagno, A. Mieles, A. M. Ortega, J. Rosado, O. Suing and station volunteers for invaluable assistance in the field. Field logistical support was obtained from the Department of Terrestrial Invertebrates at the Charles Darwin Research Station. This work was supported by a National Science Foundation Award (DEB-0817978) to A.S.S., by a Brachman Hoffman Fellowship through Wellesley College to A.S.S. and by a Howard Hughes Medical Institute grant to Wellesley College (C.C.S and A.S.S.).

Supplementary material

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Supplementary material 1 (DOCX 75 kb)


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Copyright information

© Springer Science+Business Media Dordrecht 2016

Authors and Affiliations

  1. 1.Department of Biological SciencesWellesley CollegeWellesleyUSA
  2. 2.Department of Terrestrial InvertebratesCharles Darwin Research StationPuerto AyoraEcuador
  3. 3.Graduate Program, Committee on Evolutionary BiologyUniversity of ChicagoChicagoUSA
  4. 4.Invertebrate Science Team, Ecologia Environment, Australia and Curtin Institute for Biodiversity and ClimateCurtin UniversityPerthAustralia

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