Introgression Through Rare Hybridization: A Genetic Study of a Hybrid Zone Between Red and Sika Deer (Genus Cervus) in Argyll, Scotland

Corresponding author: Nick H. Barton, Institute of Cell, Animal and Population Biology, University of Edinburgh, W. Mains Rd., Edinburgh, EH9 3JT, UK., n.barton{at}ed.ac.uk (E-mail)

Communicating editor: A. G. CLARK

In this article we describe the structure of a hybrid zone in Argyll, Scotland, between native red deer (Cervus elaphus) and introduced Japanese sika deer (Cervus nippon), on the basis of a genetic analysis using 11 microsatellite markers and mitochondrial DNA. In contrast to the findings of a previous study of the same population, we conclude that the deer fall into two distinct genetic classes, corresponding to either a sika-like or red-like phenotype. Introgression is rare at any one locus, but where the taxa overlap up to 40% of deer carry apparently introgressed alleles. While most putative hybrids are heterozygous at only one locus, there are rare multiple heterozygotes, reflecting significant linkage disequilibrium within both sika- and red-like populations. The rate of backcrossing into the sika population is estimated as H = 0.002 per generation and into red, H = 0.001 per generation. On the basis of historical evidence that red deer entered Kintyre only recently, a diffusion model evaluated by maximum likelihood shows that sika have increased at ~9.2% yr^-1 from low frequency and disperse at a rate of ~3.7 km yr^-1. Introgression into the red-like population is greater in the south, while introgression into sika varies little along the transect. For both sika- and red-like populations, the degree of introgression is 30–40% of that predicted from the rates of current hybridization inferred from linkage disequilibria; however, in neither case is this statistically significant evidence for selection against introgression.

This article has been cited by other articles:

				L. Cortes-Ortiz, T. F. Duda Jr., D. Canales-Espinosa, F. Garcia-Orduna, E. Rodriguez-Luna, and E. Bermingham Hybridization in Large-Bodied New World Primates Genetics, August 1, 2007; 176(4): 2421 - 2425. [Abstract] [Full Text] [PDF]

				E. C. Anderson and E. A. Thompson A Model-Based Method for Identifying Species Hybrids Using Multilocus Genetic Data Genetics, March 1, 2002; 160(3): 1217 - 1229. [Abstract] [Full Text] [PDF]

				E. Randi, M. Pierpaoli, M. Beaumont, B. Ragni, and A. Sforzi Genetic Identification of Wild and Domestic Cats (Felis silvestris) and Their Hybrids Using Bayesian Clustering Methods Mol. Biol. Evol., September 1, 2001; 18(9): 1679 - 1693. [Abstract] [Full Text] [PDF]

				L. Chikhi, M. W. Bruford, and M. A. Beaumont Estimation of Admixture Proportions: A Likelihood-Based Approach Using Markov Chain Monte Carlo Genetics, July 1, 2001; 158(3): 1347 - 1362. [Abstract] [Full Text] [PDF]