The establishment of a hybrid zone between red and sika deer (genus Cervus)

Authors

  • K. ABERNETHY

    Corresponding author
    1. Institute of Cell, Animal and Population Biology, University of Edinburgh, Kings Buildings, West Mains Road, Edinburgh EH9 3JT, UK
      ICAPB, Kings Buildings, Edinburgh, EH9 3JT. Tel. 031 650 5448. Fax 031 667 3210.
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  • Kate Abernethy is a PhD student at the Institute of Cell, Animal and Population Biology, Edinburgh, working with Nick Barton and Andrew Illius. Her current research on the introduction of sika deer to Scotland includes work on their feeding ecology and ranging behaviour as well as population genetics. The studentship is a CASE award with the Forestry Commission, involving liaison with their Wildlife Branch staff and much of the research presented here was also collaborative, involving Mike Bruford and his co-workers at the Institute of Zoology and Josephine Pemberton at Cambridge University.

ICAPB, Kings Buildings, Edinburgh, EH9 3JT. Tel. 031 650 5448. Fax 031 667 3210.

Abstract

Japanese sika deer (Cervus nippon nippon) were introduced to Scotland around 80 years (20 generations) ago. The sika phenotype is expanding its range and hybridizing extensively with native red deer (Cervus elaphus) leading to the establishment of a hybrid zone. This zone is currently moving and cannot be considered to be at equilibrium. Cervid genotypes and mitochondrial haplotypes were mapped across the sika phenotype range, using diagnostic protein isozymes, microsatellite nuclear DNA markers and RFLPs in mtDNA. These were analysed to estimate heterozygote deficits and nuclear linkage disequilibria and cytonuclear disequilibria in relation to gene frequencies and time since contact. Introgression was found in both taxa and strong linkage disequilibria and heterozygote deficits characterize the populations longest exposed to hybridization. Populations further from the introduction site, where hybridization is facilitated by the dispersal of sika-like stags, show low values for linkage disequilibria and heterozygote deficit. The observed patterns in genotype are explained in terms of assortative mating and a selective advantage of the sika genotype. The genetic integrity of the Scottish mainland red deer is shown to be at risk from the invasion of sika.

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