DOLAN, REBECCA W.1*, ERIC S. MENGES2, and REBECCA YAHR3. 1Friesner Herbarium, Butler University, Indianapolis, IN, 46208; 2Archbold Biological Station, PO Box 2057, Lake Placid, FL, 33862; 3Department of Botany, Box 90338, Duke University, Durham, NC, 27708. - Genetic variation in Nolina brittoniana, an endemic of the central ridges of Florida.
Nolina brittoniana is a perennial agave endemic to the central
ridges of the Florida peninsula. Its upland scrub and sandhill
habitats have suffered extensive destruction and fragmentation, and
indirect alteration through fire suppression. We examined genetic
variation in 48 populations from throughout its range using isozymes.
Features of the life history and ecology of the species led us to
predict that this federally listed plant would not be genetically
impoverished, in spite of its narrow range. However, we found lower
values for percentage of polymorphic loci, average numbers of alleles
per locus and expected heterozygosity than those generally reported
for endemic plants. Populations were fairly well differentiated (mean
FST = 0.363). Inbreeding rates were low and allele number
and frequency did not indicate recent bottlenecks. Significant clines
in allele frequency were detected along the north-south axis of
distribution. Spatial structure of genetic variation and high
population differentiation reflect the patchy distribution of scrub
habitats and support the need to preserve populations from throughout
N. brittoniana's range.
Key words: Agavaceae, Florida, isozyme analysis, Lake Wales Ridge, Nolina brittoniana, rare plants