GENETIC STRUCTURE OF THICK-BILLED MURRE (URIA LOMVIA) POPULATIONS EXAMINED USING DIRECT SEQUENCE ANALYSIS OF AMPLIFIED DNA.

Abstract

Recent research has revealed that the extent of genetic differentiation of animal populations varies greatly (reviewed by Avise et al., 1987), and appears to be negatively correlated with dispersal capability (Ball et al., 1988). Most birds are highly mobile, and correspondingly most avian populations have little if any genetic structuring (e.g., see review by Evans, 1987; also Tegelstrom, 1987; Ball et al., 1988). However, many avian species exhibit strong natal philopatry, and genetic differentiation of demes within some species is substantial, despite high dispersal capabilities (e.g., Canada geese, Branta canadensis; Van Wagner and Baker, 1986; Shields and Wilson, 1987; black brant, B. bernicla; Shields, 1990; fairy prions, Pachyptila turtur; Ovenden et al., 1991). Most previous population genetics studies of birds involved protein electrophoresis, which may not be sufficiently sensitive to detect genetic structuring in many cases. Because mitochondrial DNA (mtDNA) is haploid and maternally inherited, its effective population size is 1/4 that of nuclear genes. MtDNA is therefore affected by founder effects, bottlenecks, and genetic isolation more than are nuclear genes (Birky et al., 1983; Wilson et al., 1985). MtDNA also evolves more quickly than do nuclear-encoded proteins (Brown et al., 1979; Wilson et al., 1985), and although mtDNA analyses are based on only one locus, restriction endonuclease studies of mtDNA have proven more sensitive than protein electrophoresis in detecting genetic structure in many animal species, particularly birds (e.g., Ovenden et al., 1987; Shields and Wilson, 1987; Shields, 1990). Restriction analyses however miss many mutations, such as multiple substitutions within single