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Conservation Genetics

, Volume 9, Issue 3, pp 645–651 | Cite as

Quantifying and managing the loss of genetic variation in a free-ranging population of takahe through the use of pedigrees

  • Catherine E. Grueber
  • Ian G. Jamieson
Research Article

Abstract

Pedigree analysis has clear benefits for the genetic management of threatened populations through the evaluation of inbreeding, population structure and genetic diversity. The use of pedigrees is usually restricted to captive populations and few examples exist of their exclusive use in managing free-ranging populations. One such example is the management of the takahe (Porphyrio hochstetteri), a highly endangered, flightless New Zealand rail at risk from introduced mammalian predators and habitat loss. During the 1980’s and 90’s, as part of the takahe recovery programme, birds were translocated from the sole remnant population in Fiordland to four offshore islands from which introduced predators had been eradicated. The subsequent “island” population, now numbering 83 and thought to be at carrying capacity, has been closely monitored since founding. Detailed breeding records allow us to analyse the island pedigree, which is up to 7 generations deep. Gene-drop analysis indicated that 7.5% of genetic diversity has been lost over the relatively short timeframe since founding (2.1 generations on average; total genetic founders = 31) due to both a failure to equalise founder representation early on and subsequent disproportionate breeding success (founder equivalents = 12.5; founder genome equivalents = 6.6). A high prevalence of close inbreeding will have also impacted on genetic diversity. Predictions from pedigree modelling suggest that 90% genetic diversity will be maintained for only 12 years, but by introducing a low level of immigration from the Fiordland population and permitting the population to grow, 90% GD could be maintained over the next 100 years. More generally, the results demonstrate the value of maintaining pedigrees for wild populations, especially in the years immediately after a translocation event.

Keywords

Founders Genetic diversity Heterozygosity Porphyrio hochstetteri Threatened species 

Notes

Acknowledgments

We thank the Takahe Recovery Group, especially D. Crouchley, A. Smart, J. Christensen, B. Walter and G. Moorcroft for providing essential pedigree information on island takahe. We are also grateful to P. Ritchie and J. Waters for their helpful comments on an earlier draft of the manuscript. Our research on takahe is funded by the Takahe Recovery Group, as part of the Mitre 10 Takahe Rescue—a sponsorship partnership with the New Zealand Department of Conservation (DOC). Additional funding was provided by DOC Science, Research & Development (contract no. 3576), Landcare Research (OBI contract no. C09X0503) and the University of Otago. CEG is supported by a New Zealand Tertiary Education Commission Top Achiever’s Doctoral Scholarship.

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Copyright information

© Springer Science+Business Media B.V. 2007

Authors and Affiliations

  1. 1.Department of ZoologyUniversity of OtagoDunedinNew Zealand

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