Get access

Genetic analysis of the mating system of the common brushtail possum (Trichosurus vulpecula) in New Zealand farmland

Authors

  • A. C. Taylor,

    Corresponding author
    1. Cooperative Research Centre for Conservation and Management of Marsupials:School of Biological Sciences, Macquarie University, Sydney 2109, Australia,
    Search for more papers by this author
  • P. E. Cowan,

    1. Manaaki Whenua — Landcare Research, Private Bag 11052, Palmerston North, New Zealand
    Search for more papers by this author
  • B. L. Fricke,

    1. Cooperative Research Centre for Conservation and Management of Marsupials:School of Biological Sciences, Macquarie University, Sydney 2109, Australia,
    Search for more papers by this author
  • D. W. Cooper

    1. Cooperative Research Centre for Conservation and Management of Marsupials:School of Biological Sciences, Macquarie University, Sydney 2109, Australia,
    Search for more papers by this author

Andrea C. Taylor. Present address:School of Biological Sciences, Monash University, Wellington Road, Clayton 3168, Victoria, Australia. Fax: (613) 9905 5537; E-mail:Andrea.Taylor@sci.monash.edu.au

Abstract

We examined male reproductive success in a common brushtail possum population in New Zealand farmland. Paternity was assigned to 66 of 91 pouch young (maternity known), using a likelihood approach applied to genotypes at six microsatellite loci having an overall average exclusion probability of around 99%. The distribution of number of offspring per male was L-shaped with a standardized variance of 1.52. At least 46% of the 76 sampled reproductively mature males, bred, siring between one and four offspring each. Although breeding males were on average older and larger than nonbreeding males, the small differences did not result in a significant overall difference between the two groups in a multivariate permutation test analagous to a t-test. Paternity analysis of 22 sibling pairs (resulting from experimental removal of pouch young early in the breeding season, inducing a second oestrous) suggested that sequential mating of females with the same male was uncommon (≈ 16–27%). Whilst there was a tendency for female possums to mate with nearby males, consistent with previous observations of territorial mating behaviour in Australian populations, some interhabitat matings were also inferred. The study population displayed only a low degree of polygyny, which may in part reflect population and habitat characteristics of the study site. A comprehensive understanding of the mating system of Trichosurus vulpecula awaits genetic paternity analysis in additional populations from both Australia and New Zealand, using quantitative approaches undertaken in this study.

Ancillary