Allozyme Variation within the Carex pachystachya Complex (Cyperaceae)

The Carex pachystachya complex represents seven species noted for their extensive morphological variation. A study of allozyme variation was initiated to determine levels of genetic variation within and among populations, and to determine the level of genetic divergence among species. Progeny from 65 populations representing six species were scored for 14 enzyme systems presumably encoded by 21 loci. Oberved heterozygosity is zero in most populations and lower than the expected equilibrium values. Total genetic diversity is low, ranging from 0.019 to 0.170 within species. Average within population diversity is also low, ranging from zero to 0.097. The majority of genetic variation exists among populations as seen by the coefficient of gene differentiation, which ranges from 0.426 to 1.0. Although notable differences exists, the species are similar genetically with the standard genetic identity ranging from 0.745 up to 0.946. Low levels of genetic variation along with high amounts of differentiation agree with the pattern observed in predominately self- pollinated species, as well as possible cryptic differentiation. Low amounts of diversity within each species as well as high identities among species suggest a recent origin for the group.