by
Stephen E. W. Green
Thesis submitted for the degree of Doctor of Philosophy in Biodiversity Management
Durrell Institute of Conservation and Ecology (DICE)
University of Kent,
Canterbury,
United Kingdom
2011
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Declaration of own work
I Stephen Edward Warren Green declare that this Ph.D. thesis, entitled Evolutionary Biology and Conservation of the Hog Island Boa Constrictor is an original piece of research and contains no material that has been submitted previously, in whole or in part, for the award of any other academic degree or diploma. Except where otherwise indicated, this thesis is my own work.
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Abstract
The Hog Island Boa constrictor is a dwarfed insular race of Boa constrictor imperator endemic to two small islands (Cayo Cochino Grande and Cayo Cochino Pequeño) in the Cayos Cochinos archipelago, Honduras. During the late 1970s and 1980s the wild population was decimated by intensive and unregulated collection for the pet trade. Fortunately, conservation management appears to be promoting demographic recovery of the population. Capture-mark-recapture analysis of the Cayo Cochino Pequeño population estimates current adult census size to be in the region of 700 individuals, with genetic analysis suggesting the Cayo Cochino Grande population to be of a similar size. Although evidence of a recent genetic bottleneck was detected in both populations, the rapid rate at which the populations recovered from the demographic bottlenecking event may have prevented the loss of substantial genetic diversity. Phylogenetic analysis reveals that populations of B. c. imperator in the Cayos Cochinos and on the nearby Bay Islands form a monophyletic group that likely diverged from the mainland approximately 2 million years ago. Dwarfism has subsequently evolved rapidly in the Cayos Cochinos since the islands were last isolated from the mainland by rising sea levels at the end of the last ice age. Thus, the Cayos Cochinos and Bay Island populations represent an Evolutionary Significant Unit of high conservation priority representing both historical and recent adaptive divergence of the species on islands. Conservation management strategies should focus on conserving this important historical genetic diversity while maintaining the ecological processes responsible for phenotypic variation in the Cayos Cochinos.
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Acknowledgements
This research could not have been conducted without the help and support of a great many number of individuals and organisations, to all of whom I am deeply grateful. First of all, I would like to thank my supervisory committee, Professor Richard Griffiths, Dr. Jim Groombridge and Dr. Alison Rosser, for their constant support, advice and encouragement, and without whom, this research would not have been possible. I am also greatly indebted to Drs. Chad Montgomery, Scott Boback and Robert Reed for not only presenting me with the opportunity to pursue this research, but for providing me with continued help and support along the way.
I am truly grateful for the financial support of my sponsors; Operation Wallacea, University of Kent, Disney Wildlife Conservation Fund and British Herpetological Society and for the permissions granted by the following authorities to have allowed this work to take place; the Honduran Coral Reef Fund (HCRF), AFE-COHDEFOR and CITES. I also owe my deepest gratitude to all those who supported this research through the provision of their time, expertise, facilities and equipment.