Conservation Genetics

, Volume 15, Issue 3, pp 509–520 | Cite as

Interspecific hybridization contributes to high genetic diversity and apparent effective population size in an endemic population of mottled ducks (Anas fulvigula maculosa)

  • Jeffrey L. PetersEmail author
  • Sarah A. Sonsthagen
  • Philip Lavretsky
  • Michael Rezsutek
  • William P. Johnson
  • Kevin G. McCracken
Research Article


Under drift-mutation equilibrium, genetic diversity is expected to be correlated with effective population size (N e ). Changes in population size and gene flow are two important processes that can cause populations to deviate from this expected relationship. In this study, we used DNA sequences from six independent loci to examine the influence of these processes on standing genetic diversity in endemic mottled ducks (Anas fulvigula) and geographically widespread mallards (A. platyrhynchos), two species known to hybridize. Mottled ducks have an estimated census size that is about two orders-of-magnitude smaller than that of mallards, yet these two species have similar levels of genetic diversity, especially at nuclear DNA. Coalescent analyses suggest that a population expansion in the mallard at least partly explains this discrepancy, but the mottled duck harbors higher genetic diversity and apparent N e than expected for its census size even after accounting for a population decline. Incorporating gene flow into the model, however, reduced the estimated N e of mottled ducks to 33 % of the equilibrium N e and yielded an estimated N e consistent with census size. We also examined the utility of these loci to distinguish among mallards, mottled ducks, and their hybrids. Most putatively pure individuals were correctly assigned to species, but the power for detecting hybrids was low. Although hybridization with mallards potentially poses a conservation threat to mottled ducks by creating a risk of extinction by hybridization, introgression of mallard alleles has helped maintain high genetic diversity in mottled ducks and might be important for the adaptability and survival of this species.


Coalescent Phenotype Introgression Population structure Multilocus phylogeography mtDNA Introns 



Shawn Houston provided high-performance computing through the University of Alaska’s Life Science Informatics Portal. Funding was provided by the National Science Foundation (Alaska EPSCoR EPS-0346770) and the Texas Parks and Wildlife Department. J Pearce and two anonymous reviewers provided valuable comments on drafts of this manuscript. Any use of trade names is for descriptive purposes only and does not imply endorsement of the US Government.

Supplementary material

10592_2013_557_MOESM1_ESM.docx (18 kb)
Supplementary material 1 (DOCX 18 kb)


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Copyright information

© Springer Science+Business Media Dordrecht 2013

Authors and Affiliations

  • Jeffrey L. Peters
    • 1
    • 2
    Email author
  • Sarah A. Sonsthagen
    • 2
    • 3
  • Philip Lavretsky
    • 1
  • Michael Rezsutek
    • 4
  • William P. Johnson
    • 5
    • 6
  • Kevin G. McCracken
    • 2
    • 7
  1. 1.Department of Biological SciencesWright State UniversityDaytonUSA
  2. 2.Institute of Arctic BiologyUniversity of Alaska FairbanksFairbanksUSA
  3. 3.United States Geological Survey, Alaska Science CenterAnchorageUSA
  4. 4.Texas Parks and Wildlife DepartmentPort ArthurUSA
  5. 5.Texas Parks and Wildlife DepartmentCanyonUSA
  6. 6.U.S. Fish and Wildlife Service, National Wildlife Refuge System, Division of Biological SciencesWest Texas A&M UniversityCanyonUSA
  7. 7.Department of Biology and Rosenstiel School of Marine and Atmospheric SciencesUniversity of MiamiCoral GablesUSA

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