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

Dudaniec, Rachael LU ; Gardner, M. G.; Donnellan, S. and Kleindorfer, Sonia (2008) In BMC Ecology 8(13). p.13-13
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 Galapagos 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... (More)
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 Galapagos 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 Galapagos avifauna. Our findings are relevant for assessing the viability of methods to control P. downsi on Galapagos, such as the sterile insect technique. (Less)
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author
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Genetic Variation, Gene Frequency, Gene Flow, Finches/ parasitology, Molecular, Evolution, Ecuador, Ecosystem, Mitochondrial/ genetics, DNA, Animals, Bayes Theorem, Genetics, Population, Geography, Microsatellite Repeats, Muscidae/ genetics, Population Dynamics
in
BMC Ecology
volume
8
issue
13
pages
13 - 13
publisher
Springer
external identifiers
  • scopus:50849092890
ISSN
1472-6785
DOI
10.1186/1472-6785-8-13
language
English
LU publication?
no
id
4d1bf4c2-5ddc-4d78-839f-4eed627fecf6 (old id 3738416)
date added to LUP
2013-05-23 13:32:19
date last changed
2017-07-02 04:02:39
@article{4d1bf4c2-5ddc-4d78-839f-4eed627fecf6,
  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 Galapagos 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. <br/><br>
<br/><br>
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. <br/><br>
<br/><br>
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 Galapagos avifauna. Our findings are relevant for assessing the viability of methods to control P. downsi on Galapagos, such as the sterile insect technique.},
  author       = {Dudaniec, Rachael and Gardner, M. G. and Donnellan, S. and Kleindorfer, Sonia},
  issn         = {1472-6785},
  keyword      = {Genetic Variation,Gene Frequency,Gene Flow,Finches/ parasitology,Molecular,Evolution,Ecuador,Ecosystem,Mitochondrial/ genetics,DNA,Animals,Bayes Theorem,Genetics,Population,Geography,Microsatellite Repeats,Muscidae/ genetics,Population Dynamics},
  language     = {eng},
  number       = {13},
  pages        = {13--13},
  publisher    = {Springer},
  series       = {BMC Ecology},
  title        = {Genetic variation in the invasive avian parasite, Philornis downsi (Diptera, Muscidae) on the Galapagos archipelago},
  url          = {http://dx.doi.org/10.1186/1472-6785-8-13},
  volume       = {8},
  year         = {2008},
}