Genetic variation in the invasive avian parasite, Philornis downsi (Diptera, Muscidae) on the Galápagos archipelago

Rachael Y. Dudaniec, Michael G. Gardner, Steve Donnellan, Sonia Kleindorfer*

*Corresponding author for this work

Research output: Contribution to journalArticle

21 Citations (Scopus)
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Abstract

Background. Understanding the dispersal and genetic structure of invasive insects across islands is important for designing management plans that are appropriate at spatial and temporal scales. For invasive parasites, population dynamics are largely determined by the distribution and density of their host species. The introduced parasitic fly, Philornis downsi, parasitises nestlings of endemic birds on all major islands of the Galápagos archipelago. The fly's high mortality and fitness impacts are of conservation concern for vulnerable and declining species of Darwin's finches. Using microsatellite data in Bayesian clustering and landscape genetic analyses, we examine gene flow and dispersal in P. downsi between three islands and across habitats (highlands, lowlands) and examine for the presence of population bottlenecks. We also examine variation at the mitochondrial gene CO1 across islands to establish if cryptic species were present. Results. Both the mitochondrial and microsatellite data were consistent with there being a single species across islands. We found low genetic differentiation between islands and strong evidence for inter-island gene flow, or shared recent ancestry among individuals. Landscape genetic analysis identified two genetic clusters: one encompassing Santa Cruz and Isabela, and one on Floreana Island. There was no evidence of genetic differentiation between habitats and molecular variance was mainly attributable to within individuals. The combined P. downsi population was found to have undergone a population bottleneck. Conclusion. Philornis downsi populations have high connectivity within and between islands, with low levels of genetic differentiation between Floreana and the other two islands examined. The genetic bottleneck found across islands suggests there was a small founding population or few introduction events of P. downsi. The high dispersal capacity and wide habitat use of P. downsi highlights the significant threat that this parasite poses to the Galápagos avifauna. Our findings are relevant for assessing the viability of methods to control P. downsi on Galápagos, such as the sterile insect technique.

Original languageEnglish
Article number13
Pages (from-to)1-13
Number of pages13
JournalBMC Ecology
Volume8
DOIs
Publication statusPublished - 2008
Externally publishedYes

Bibliographical note

Copyright the Author(s) 2008. Version archived for private and non-commercial use with the permission of the author/s and according to publisher conditions. For further rights please contact the publisher.

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