Mitochondrial DNA analysis of hybridization between sympatric white-tailed deer and mule deer in west Texas.

Abstract

Sympatric populations of white-tailed deer and mule deer (Odocoileus virginianus and Odocoileus hemionus, respectively) on a west Texas ranch share a common mitochondrial DNA restriction map genotype. Phylogenetic analysis indicates that this genotype is more characteristic of 0.virginianus than of 0. hemionus. The genotype of west Texas deer differs from that of 0. virginianus from South Carolina by five mutational events (1.3% sequence divergence), whereas it differs from that of 0. hemionus from California by 17 events (5.5% divergence). We suggest that interspecies hybridization has occurred, primarily between mule deer bucks and whitetailed deer does, with preferential absorption of hybrid offspring into the mule deer gene pool. Introgressive hybridization may be involved in ongoing displacement of mule deer by white-tailed deer in west Texas.Natural hybridization between white-tailed deer (Odocoileus virginianus) and mule deer or black-tailed deer (Odocoileus hemionus) has long been suspected (1, 2). In New Mexico and west Texas, white-tailed deer have expanded their range westward at the expense of mule deer for some 40 years, and it has been suggested that hybridization might contribute to this displacement. Captive-breeding studies indicate that interspecific crosses are possible. Although most such matings are sterile, both reciprocal crosses can produce viable offspring, and at least some of these F1 progeny have been fertile in all backcross combinations (3, 4). This problem is of interest from both practical and theoretical considerations. Deer are among the most economically important wildlife species in the United States (5), and hybridization between species of ungulates or other large mammals appears to be rare in nature (6, 7). We are aware of only one published genetic study of natural hybridization among ungulates, a study of bison subspecies (8). Up to the present, the hypothesis of interspecies hybridization in deer has not been tested by quantitative genetic means.Mitochondrial DNA (mtDNA) has been used extensively in studies of population biology in recent years (9-11). The entire molecule has been sequenced in four vertebrate species, as a result of which the positions and natures of the coding sequences, tRNA genes, and rRNA regions are known. The gene order is identical in the four species sequenced thus far (12-15). Because mtDNA is a separate genetic system, outside the nucleus, and seems to be strictly maternally inherited, it has been used as a probe of interspecies gene flow (16)(17)(18)(19)(20)(21).The two species of the genus Odocoileus are distributed throughout North America. Mule deer (including conspecific black-tailed deer of the Pacific Northwest) are primarily western animals, whereas white-tailed deer are more common in the central and eastern United States and in Central America. The two species are broadly sympatric over much oftheir range (22). They are distinguished morphologically by several criteria, including the form of the antlers and the size of the met...

Heritabilities for antler characteristics and body weight in yearling white-tailed deer

“…White-tailed deer are believed to possess a high level of heterozygosity (Smith et at., 1976;Breshears et a!., 1988;Scribner et at., 1984Scribner et at., , 1989Scribner & Smith, 1990). A review of papers by Carr et at., (1986), Derr (1991, Derr et at. (1991) and Ballinger et at.…”

Mitochondrial Analysis of Gene Flow between New Zealand Mallards (Anas platyrhynchos) and Grey Ducks (A. superciliosa)

“…This adds to the increasing number of examples of mitochondrial gene exchange betw^een species in other taxa (e.g. mammals [Ferris et al 1983, Carr et al 1986, Tegelstrom 1987, Lehman et al 1991, amphibians [Spolsky andUzzell 1984, Lamb andAvise 1986], and fish [Avise and Saunders 1984]). …”

Novel chloroplast DNA polymorphism in a sympatric region of two pines1

“…However, in several studies of extranuclear DNA polymorphisms in hybrid zones, sample sizes have been too small to permit the detection of rare variants, or the numbers of these variants have been too few to be interpreted confidently as limited to geographic regions of 'Journal Paper No. 88.8.11 hybridization (Ferris et al, 1983;Powell, 1983;Avise and Saunders, 1984;Hale and Beckenbach, 1985;Carr et al, 1986;Lamb and Avise, 1986;Wagner et al, 1987). One of the major extranuclear genomes, the chloroplast genome, is a circular molecule, encoding functions essential for plastid protein synthesis (Whitfeld and Bottomley, 1983).…”