Advisors: Dr. Stanley F. Fox and Dr. Christopher J. Raxworthy (American Museum of Natural History)
General Research Interests: Herpetology, lizard ecology, evolutionary ecology, behavioral ecology, sexual selection, phylogeography, and community ecology.
Dissertation title: Sexual selection, mating systems, behavior, and population status of chameleons in southwest Madagascar
Typically, species that are closely related should be broadly similar in morphology. However, in southwest Madagascar, there are four closely related chameleon species that are strikingly different in morphological characters. Some have large casques, some have rostral appendages, some have large dorsal crests, and some species have males nearly twice as large as females. However, there are other species lacking all or some combination of these characters in the southwest. To have such diverse morphology in such a closely related phylogenetic lineage, there must be very strong selection to cause these differences in mophological characters. Furthermore, these characters are usually sexually selected.
For my dissertation research, I am testing hypotheses of mating systems, intrasexual selection (male-male competition for mates), and intersexual selection (female mate choice) to delineate their roles (or lack thereof) in the evolution of such diverse morphology in a closely related group of chameleons. My research focuses on four species of chameleons in southwest Madagascar near Tuléar (Toliara): Furcifer antimena, F. labordi, F. lateralis, and F. verrucosus. The two main objectives of my dissertation are to 1) quantify intra- and intersexual selection with respect to sexual size dimorphism (SSD) and secondary sexual characters (SSCs) and 2) describe the mating systems of these four chameleon species.
As a corollary to my main study, I am also collecting population data on all
four species of the sexual selection study. These data will be used to determine
population densities and population age and sex structure; data vital to determining
how conservation efforts should be implemented in the Tuléar region.
Additionally, we are attempting to collect population/conservation data on a
fifth species, F. belalandaensis. Furcifer belalandaensis
has only been found in one specific location in southwestern Madagascar and
is usually considered one of, if not the rarest chameleon species in the world
(if it is not already extinct). We are presently trying to determine if it still
occurs in the southwest, and if so, what is the current population status. Data
on this species, and others in the southwest, are urgently needed.
Other current research:
The effects of incubation environment on performance, survival, territory acquisition, and reproductive success in collared lizards with Jerry Husak (Fox Lab, OSU) and Day Ligon (Lovern Lab, OSU).
Basking behavior, UV photoregulation, and microhabitat use in panther chameleons (Furcifer pardalis) with Gary Ferguson (TCU).
UV photoregulation and basking behavior in Jamaican Anolis lizards with Gary Ferguson (TCU), Bill Gehrmann, Tai Chen (Boston University Medical Center), and Michael Holick (Boston University Medical Center).
Thermoregulation, microhabitat use, and social organization in collared lizards (Crotaphytus collaris) with Jerry Husak (Fox Lab, OSU).
Karsten, K. B. and G. W. Ferguson. Outdoor enclosure design and technique for studying three-dimensional movement patterns of arboreal lizards. Herpetological Review. In press.
Ferguson, G. W., W. H. Gehrmann, K. B. Karsten, S. H. Hammack, M. McRae, T. C. Chen, N. P. Lung, and M. F. Holick. 2003. Do panther chameleons bask to regulate endogenous vitamin D3 production? Physiological and Biochemical Zoology. 76(1): 52-59.
Back to Fox Lab