Reconciling molecular signatures across markers: mitochondrial DNA confirms founder effect in invasive North American house finches (<Emphasis Type="Italic">Carpodacus mexicanus</Emphasis>) |
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Authors: | Dana M Hawley James Briggs André A Dhondt Irby J Lovette |
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Institution: | (1) Laboratory of Ornithology, Cornell University, Ithaca, NY 14850, USA;(2) Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, NY 14853, USA;(3) Department of Biology, Virginia Tech, 3030 Derring Hall, Blacksburg, VA 24061, USA |
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Abstract: | Well-characterized species introductions provide opportunities to compare the genetic signatures of known founder effects
across classes of molecular markers. The release of small numbers of house finches (Carpodacus mexicanus) into the eastern United States in the 1940s led to substantial interest in the effects of this introduction on genetic diversity
in this now abundant species, an issue that has been highlighted by a recent Mycoplasma disease epidemic that most intensively affects the introduced and potentially genetically depauperate house finch populations.
Previous studies comparing genetic diversity levels in native and introduced house finch populations produced seemingly disparate
results: comparisons based on amplified fragment length polymorphism, RFLP mtDNA, and allozyme markers found essentially equivalent
levels of diversity in eastern and western populations, whereas microsatellite markers showed clear reductions in diversity
in the introduced populations. Here we employ sequence variation at the ND2 mtDNA locus to further compare levels of diversity
between the four native and five introduced house finch populations that were previously examined in the microsatellite study.
We found substantially lower ND2 haplotype richness and diversity across all introduced populations of house finches. The
majority of sequence variation (78%) was detected within subpopulations, with the remainder (22%) explained by the historical
status of each population (native or introduced). Our results are consistent with previous microsatellite evidence for a founder
effect during the introduction of eastern house finches, and suggest that the mtDNA founder effect was particularly severe,
likely owing to a male-biased sex ratio at the time of introduction coupled with the lower effective population size of clonally
inherited markers. We discuss how the inconsistencies between past studies of house finch diversity can inform the usefulness
of distinct marker sets for detecting molecular signatures of founder events. |
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Keywords: | Population bottleneck Founder effect Mitochondrial DNA Introduced species Genetic diversity House finch ND2 locus |
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