GENOTYPIC DIVERSITY IN OENOTHERA LACINIATA (ONAGRACEAE), A PERMANENT TRANSLOCATION HETEROZYGOTE.

Abstract

Electrophoretic studies have revealed remarkable variability within and among populations of several unisexual animal species. Multiple genotypes, detected by various allozyme phenotypes, exist for unisexual insects (Parker et al., 1977; Suomalinen et al., 1977; Mitter et al., 1979), fishes (Schultz, 1977), lizards (Uzzell and Darevsky, 1975; Parker and Selander, 1976) and annelids (Christensen et al., 1976; Jaenike and Selander, 1979). The few studies employing allozymes as genetic markers for clonal plant species have either focused closely on one or a few populations (Solbrig and Simpson, 1974; Hancock and Wilson, 1976; Hancock, 1977; Steiner and Levin, 1977; Silander, 1979) or concentrated mainly on interpopulational differences (Solbrig, 1971; Levin, 1975; Levy and Winternheimer, 1977; Ellstrand and Levin, 1980a, 1980b). No study has yet described genotypic diversity both within plant populations and over the range of a clonal plant species. The object of this study is to obtain a minimal determination of levels of diversity in a clonal plant species and compare these levels with those exhibited within and among populations of unisexual animal species. The species chosen for study is Oenothera laciniata Hill, an annualwhich occurs in disturbed sandy soils from Texas east to the Atlantic coast and north to Illinois and New Jersey (P. Raven, pers. comm.). This species is a permanent translocation heterozygote, cytogenetically studied throughout its range (Hecht, 1950; Gregory and Klein, 1960; McMullen, 1966; Cleland, 1968; P. Raven and W. Dietrich, pers. comm.). Permanent translocation heterozygosity is an unusual genetic system which results in an effectively asexual mode of reproduction (for details, see Cleland, 1972). Oenothera laciniata is probably a derivative of 0. grandis Smyth, an outcrosser with a conventional genetic system, which occurs primarily in south and central Texas (Munz, 1965; Ellstrand and Levin, 1980b).