PARENT SESSION
Contributed Oral Session 87: Rare, Threatened, and Endangered Species: Flora; Habitat
Wednesday, August 10, 8:00 AM - 11:30 AM, Meeting Room 522 A, Level 5, Palais des congrès de Montréal

Metapopulation ecology and genetics of the Florida scrub endemic Polygonella basiramia.

Boyle, Owen^*,1, ¹ Wisconsin Department of Natural Resources, Milwaukee, WI

ABSTRACT- Polygonella basiramia is a rare plant endemic to the naturally patchy, fire-driven Florida scrub ecosystem. I analyzed long-term demographic data using metapopulation approaches to determine how habitat patch properties affect patch occupancy and turnover. P. basiramia inhabits white sand gaps in the Florida rosemary-dominated community that itself occurs patchily, allowing me to explicitly consider the scale of metapopulation dynamics. Logistic regression shows that the incidence of P. basiramia within gaps increases in larger, less isolated gaps. From 1999 to 2002, turnover among 1,210 gaps was 8%/year with local extinctions outpacing colonizations. The probability of local extinction decreases with increasing gap area. The probability that a vacant gap is colonized rises with gap area and proximity to other occupied gaps. I also used Bayesian methods to estimate genetic diversity and structure from 102 polymorphic Amplified Fragment Length Polymorphism (AFLP) markers at the large scale (among rosemary patches) and 81 markers at the small scale (among gaps within rosemary patches). Within-deme heterozygosity was moderate at both scales (Hs = 0.263) and was not correlated with deme age, patch area, or isolation. Population differentiation as measured by F_ST was low (large scale = 0.046, small scale = 0.140) and decreased with patch age. Patterns of gene flow and genetic structure are consistent with the rapid turnover dynamics observed in the field.

Key words: metapopulation dynamics, genetic diversity, Polygonella basiramia, Florida scrub