Geiger, John .
Experimental seed and seedling performance of the endangered vine Ipomoea microdactyla Griseb. (Convolvulaceae).
Habitat loss and fragmentation are the primary threats to the persistence of an increasing number of species. The main effects of fragmentation are reductions in population size and isolation of the remaining populations. Theory predicts several potential negative consequences as a result, such as, genetic erosion, reduced reproduction, inbreeding depression and decreased fitness of progeny. Beginning in the 1980s conservation biologists have been engaged in a debate over the relative importance of demographic and genetic factors for the population viability of rare species. The body of scientific knowledge concerning the effects of habitat fragmentation on both common and rare plant species has grown considerably in this span of time. Still the conflict between the significance of demographic and genetic processes in determining population persistence is an active field. An experimental approach is one way to address this question. The purpose of this research is to gauge the demographic performance (i.e. growth, survival and reproduction) of experimentally outplanted seeds and seedlings derived from small and large populations. The study species is Ipomoea microdactyla Griseb. (Convolvulaceae), a hermaphroditic, self-incompatible vine occurring in Miami-Dade County, Florida (USA). Presently the species is restricted to the remaining 2 % of pine rockland habitat found in Miami-Dade County. Results from the seed outplanting experiment show significant differences in both germination and survival for the factors of planting site and seed provenance over the two year study. There are significant differences in the growth, survival and reproduction of the outplanted seedlings for the factors of site and seedling provenance. The superior performance of seeds and seedlings generated from small populations is surprising. These results can be explained by the recent fragmentation of this habitat coupled with the long-lived individuals. It appears that remaining populations, even at densities less than 50 individuals, harbor high levels of genetic variation.
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1 - Florida International University, Biological Sciences, 11200 S.W. 8th ST., Miami, Florida, 33199, USA
Presentation Type: Oral Paper:Papers for Sections
Location: Lake Ontario/Hilton
Date: Monday, July 9th, 2007
Time: 1:30 PM