CHARACTERIZATION OF MITOCHONDRIAL DNA VARIABILITY IN A HYBRID SWARM BETWEEN SUBSPECIES OF BLUEGILL SUNFISH ( LEPOMIS MACROCHIRUS )

Abstract

Genetic variation in mitochondrial have chosen an evolutionary setting (a DNA (mtDNA) has been studied in pop-local subspecies hybrid swarm) which ulations of mammals, Drosophila, and a should facilitate analysis of several posfew other higher animals (reviews in Av-sible features of mtDNA variation. Disise and Lansman, 1983;Brown, 1983). tinctive mtDNA genotypes contributed Among the noteworthy features of by the parental subspecies to the hybrid mtDNA variability pertinent to the anal-swarm are identified. As described later, ysis of evolutionary process are the fol-these provide a special opportunity to lowing: a rapid rate of evolution involv-recognize paternally-generated mtDNA ing primarily base substitutions plus very heteroplasmicity, if it does exist, both in small addition/deletions (Brown et al., somatic and germ cells. Study of the as-1979; Cann and Wilson, 1983); a re-sociation between allozyme and mtDNA markable stability of gene content and markers permits comparison of the evoarrangement; apparent mtDNA se-lutionary consequences ofbiparental verquence homogeneity (homoplasmicity) sus uniparental transmission of genoin somatic cells within an individual or-types across animal generations. We will ganism; extensive sequence polymor-also include a description of mtDNA sephism among con specifics; and maternal quence variation across a broader range transmission ofmtDNA to progeny. Em-of the species. At this macrogeographic pirical and conceptual reservations apply level, is the evolutionary divergence in to some of these generalities. For ex-mtDNA, reflecting matriarchal phylogample, low frequency mtDNA variants eny, concordant with the subspecies diswithin an individual would normally es-tributions defined by morphology and by cape empirical detection, and, given the allozymes encoded in the nuclear geubiquity of between-individual sequence nome? differences, it would seem that at least MATERIALS AND METHODS some transient mtDNA heteroplasmicity (perhaps in germ cell lineages) is ineviTaxa Examined table (see Olivo et al., 1983). Also, the Two subspecies of bluegill, originally consequential possibility remains that described by morphologic criteria, are some mtDNA molecules are successfully native to the southeastern United States transmitted to progeny from the male (Hubbs and Allen, 1944; Miller and parent (paternal leakage; but see Lans-Winn, 1951). Lepomis macrochirus purman et al., 1983).purescens, abundant in peninsular FlorThe main purpose of this study is to ida and Atlantic coastal streams, differs begin the characterization of mtDNA slightly in quantitative morphologic and polymorphism in another class of ver-physiologic features from L. m. macrotebrates-the fishes. Our approach has chirus, the bluegill inhabiting the Missisbeen to map mtDNA restriction site vari-sippi and other Gulfdrainages east to the ation in the bluegill sunfish (Lepomis Chattahoochee River in Georgia (Hubbs macrochirus;Centrarchidae), using a large and Lagler, 1958). A recent protein-elecnumber of restriction endo...

Mitochondrial DNA Sequence Similarity of Atlantic and Pacific Albacore Tuna (Thunnus alalunga)

“…Analysis of fragment sizes resulting from digestions with Ava I, Eco RI, Hinc 11, and Hind I11 produced a mean genome size of 16 750 -e 200 nucleotide base pairs for the albacore mitochondrial genome (Table 1). This value lies within the 16 300 to 19 800 base pair range reported for other fish mtDNAs (Avise et al 1984;Berg and Ferris 1984;Graves et al 1984;Beckwitt and Petruska 1985;Bentzen et al 1988). …”

“…At a level of analysis comparable with the present study, both in numbers of individuals and restriction fragments surveyed, significant intraspecific differentiation has been demonstrated in pocket gophers of different counties (Avise et al 1979), deer mice of different counties (Lansman et al 1983), and different coastal islands (Ashley and Wills 1987), cotton rats of the same field (Kessler and Avise 1985), bluegill within the same drainage system (Avise and Saunders 1984;Avise et al 1984), cutthroat trout from different drainage systems (Gyllensten et al 1985), horseshoe crabs of the Atlantic and Gulf coasts of Florida , and toadfishes of the Atlantic coast of the United States (Avise et al 1987). No such differentiation was found between albacore of the north Pacific and south Atlantic.…”

Mitochondrial DNA differentiation in the Japanese brown frog Rana japonica as revealed by restriction endonuclease analysis.

“…Several studies have provided evidence for interspecific mtDNA transfer in the absence of nuclear gene introgression (Ferris et al, 1983;Powell, 1983;Spolsky and Uzzell, 1984). On the other hand, nuclear and mitochondrial genes were found to change concordantly within hybrid populations or in a transect across hybrid zones (Avise et al, 1984;Szymura et al, 1985;Harrison et al, 1987;Wallis and Arntzen, 1987;Rand and Harrison, 1989;Sumida and Ishihara, 1997). The present study suggests that mitochondrial gene flow may have occurred into the Akita population from the eastern populations of R. japonica.…”

Atypical mitochondrial DNA from the deep-sea scallop Placopecten magellanicus

“…Our data do not support duplication as the origin, for two reasons. First, there is no (23). Differences in size have been reported in population surveys of bowfin fish and tree frogs (24), in a nematode (19), in crickets (25), and in several species of lizard (26,27).…”