Habitat loss leads to a decrease in the total area of suitable habitat, and to the isolation of remaining habitat into fragments. I examined the effects of fragmentation on both demographic and genetic features of the rare epiphytic Malagasy orchid Erasanthe henrici at broad spatial and temporal scales. Erasanthe henrici is also threatened by overcollection, which affects orchid species worldwide.
I detected relatively low levels of genetic differentiation among populations using microsatellite markers. The lack of regional differences in genetic diversity suggests that fragmentation of these populations is a recent phenomenon. My demographic analyses suggest that all but the largest populations have a high extinction risk. Legal protection of forests reduces the rate of forest destruction and the frequency with which plants are collected for the horticultural market. When I incorporated varying levels of harvest I found that populations declined under all harvest scenarios, but most severely under those where only reproductive plants were being harvested. Malagasy orchids are harvested for both the local and international markets, and my analysis of exportation data found that the effects are not equal across species. My research identified highly traded species that would benefit from further study.
|Advisor:||Holsinger, Kent E.|
|Commitee:||Anderson, Gregory J., Holsinger, Kent E., Silander, John A., Jr.|
|School:||University of Connecticut|
|Department:||Ecology and Evolutionary Biology|
|School Location:||United States -- Connecticut|
|Source:||DAI-B 74/04(E), Dissertation Abstracts International|
|Subjects:||Biology, Plant biology, Conservation|
|Keywords:||Demography, Endemic orchid, Erasanthe henrici, Madagascar|
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