GENETIC DIFFERENTIATION BETWEEN CAREX LASIOCARPA AND C-PELLITA (CYPERACEAE) IN NORTH-AMERICA

Carex lasiocarpa and C. pellita (sect. Carex) share a very similar mor phology and have overlapping ranges in North America, but are found in different habitats characterized by contrasting soil types and pH. We studied allozyme variation and chromosome numbers to assess genetic d ifferentiation between the two taxa. Both principal components analysi s on the allele frequencies from 12 putative enzyme-coding loci and cl uster analysis of genetic identities separated 51 sampled populations into two groups that were consistent with recognized structural differ ences between C. lasiocarpa and C pellita. Mean within-group genetic i dentities were 0.95 for C. lasiocarpa and 0.93 for C. pellita; mean be tween-group genetic identity was 0.81. With the exception of two rare alleles, the alleles of C. pellita were a subset of those found in C. lasiocarpa. Principal components analysis of measurements of structura l characters from voucher specimens representing 46 populations also s eparated the two species with minimal overlap. Meiotic squashes of mic rosporocytes revealed haploid chromosome numbers of 38 and 38 + 1 for C. lasiocarpa and 41 and 40 + 1 for C pellita. These data support the continued recognition of the two taxa as distinct species, and suggest that C. pellita may be a daughter species still in the process of div ergence from C. lasiocarpa.