12/22/08

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(1) I investigated species diversity and community organization in the ant faunas of remote Polynesian islands, to which all ant species have been introduced and share no common coevolutionary history in the region.  The conventional wisdom was that remote Polynesian islands were depauperate in ants compared to less remote islands, due to a small species pool and fierce interspecific competition that resulted in complementary distributions of ant species among islands.  I discovered, however, that species numbers were low because the islands had not been thoroughly collected. Interspecific competition was not as strong a force as previously believed, and patterns of ant species distributions among islands were highly nested.  I documented hierarchical patterns of community structure and function in these 'synthetic' ant faunas that are analogous to those found in coevolved mainland ant communities.

Publications on Polynesian island biogeography
 

(2) I have investigated the metapopulation dynamics of ants and plants inhabiting four archipelagos of small islands in the Bahamas (encompassing >200 islands overall), documenting patterns of immigrations and extinctions and elucidating factors underlying turnover events.  I have found that populations of ants and plants occupying these small islands are very persistent over periods of years to a decade (in the absence of major disturbances), and I now have data spanning 13 years for many islands.  Such long-term data sets are extremely rare, although many important processes occur over such time scales.
 

All four of my study archipelagos were recently disturbed by hurricanes, presenting an opportunity to investigate the degree of resistance and resilience these taxa possess when affected by such disturbances.  I have also studied the terrestrial invertebrates occupying very small islands that lack terrestrial vegetation.  Such islands contain relatively diverse arthropod faunas, encompassing several trophic levels, that are entirely dependent upon the marine environment for energy inputs.  These islands hold insight into early successional processes, the base of insular food webs, and life in extreme environments.

Publications on Bahamian island biogeography

(3) I am interested in the structure and function of mainland ant and associated arthropod communities and how invasive species impact native communities.  I have investigated the mechanisms of competitive asymmetries among native and invasive fire ant species, discovering that a numerical advantage is of primary importance in the displacement of native ants.  I have also documented how native ant and arthropod communities were affected in the long term (>10 years) by the imported fire ant (Solenopsis invicta).  Although native arthropod communities have revealed relatively little resistance to this invader in the short term, I found that, after a decade, populations of other ants and arthropods had rebounded to near pre-invasion levels, demonstrating a surprising degree of resilience in native arthropod assemblages.

Publications on invasive ants
 

(4) I am interested in the factors limiting populations in general.  Interspecific competition among ants has often been demonstrated to be an important factor regulating ant populations.  Other types of interspecific interactions, however, such as predation, parasitism, and interspecific competition with other types of organisms have been studied relatively rarely.  A small but increasing body of evidence indicates that some predators and parasites may have large impacts on worker ant behavior and ultimately population abundance.  Predators and parasites may have relatively small direct but large indirect effects, changing the behavior of their host or prey and causing them to be at a competitive disadvantage relative to other ant species.  I have found that predatory ant lions and parasitoid phorid flies may at times have large impacts on ant behavior. I have also documented the first evidence of direct competition between ants and land crabs.

Publications on ant parasitoids, predators, and competitors

(5) Finally, I am interested in the application of findings from my basic research to conservation efforts.  My work with insular metapopulations has important implications for species occupying fragmented habitats and the design of nature preserves.  My work with the National Park Service’s Natural Resources Inventory and Monitoring Program will elucidate long-term patterns of population viability in preserved habitats.  This data will be invaluable to natural resource managers and planners. My current work focuses on the design of long-term monitoring programs and approaches to the statistical analysis of the the resulting data.

Publications on ecological monitoring