Collaborative Research
Evolution and biogeography of rattlesnakes (Crotalus and Sistrurus)     I have been working with Harry Greene (Cornell University), David Hillis (University of Texas at Austin), Javier Rodriguez (University of Nevada, Las Vegas) and Jonathan Campbell (University of Texas at Arlington) investigating the phylogenetic relationships among species of rattlesnakes.	Crotalus molossus, a personal friend.
Rattlesnakes (genera Crotalus and Sistrurus) are widespread in the New World and are a particularly interesting group because of the diversity of habitats they occupy (ranging from deserts to montane habitats), their biogeographic history, and particularly, the evolution of the rattle, the noise making appendage that is a synapomorphy for this clade. We obtained multiple samples of all species of rattlesnakes and multiple outgroups; last Fall (1998) we completed the data collection for this project. We have sequenced three mitochondrial gene fragments (ND4, ND2, and a fragment spanning the 12S/16S genes) for a total of 2600 base pairs. Once we have a working hypothesis about relationships within this group, we will use the phylogeny to address questions about the origin and geographic diversification of this clade, the biogeographical history of rattlesnakes, and what this history tells us about the evolution of the rattle.
Phylogeography, population differentiation and gene flow in reptiles and amphibians of Atlantic Coastal Forest, Brazil I am collaborating with Márcio Martins (Universidade de São Paulo) and Célio Haddad (Universidade Estadual de São Paulo, Rio Claro) and their students on various projects examining population connectivity and patterns of differentiation in vertebrates of southeastern Brazil.	Cycloramphus boraceiensis, an Atlantic Coastal Forest endemic
One of our studies focuses on the genetic connectivity and gene flow among coastal populations of the fer-de-lance Bothrops jararaca, and two species that inhabit islands off the coast of São Paulo state (B. insularis and B. alcatraz). We are using microsatellites to infer patterns of gene flow and connectivity in coastal populations and the origin and differentiation of the island endemics. This project includes two additional collaborators: Chris Parkinson (University of Central Florida), and Otávio Marques (Instituto Butantan, Brazil) A second project examines differentiation and patterns of gene flow among populations of a frog (Cycloramphus boraceiensis) and a fish (Trichogenes longipinnis) that are habitat specialists and live in forest streams in Atlantic Coastal Forest. Given their habitat specificity and the possibility of reduced overland dispersal, we hypothesize that patterns of genetic diversity will mirror patterns of stream connectivity. We are using molecular markers to infer dispersal at various geographic scales (within streams, among streams within drainages, and among drainages). Finally, I am interested in patterns of differentiation, speciation, and diversity in endemic Atlantic Forest taxa and am therefore reconstructing a population-level phylogeny for Cycloramphus boraceiensis, a widespread frog, and a species level phylogeny for the genus Cycloramphus. Bothrops alcatraz, an endemic of Ilha Alcatrazes, São Paulo State, Brazil. Trichogenes longipinnis, a freshwater catfish that inhabits Atlantic Coastal Forest streams, São Paulo, Brazil. More Brazil Photos... Population genetics and conservation of bog turtles (Clemmys muhlenbergii) and the Florida scrub sand skink (Neoseps reynoldsii) I am interested in the genetic consequences of habitat specificity for taxa that occupy fragmented or patchy habitats, and am involved in two collaborations examining population differentiation in two such species that are threatened or endangered due to alteration of habitat. With Peter Rosenbaum (SUNY OSwego) I am examining population-level differentiation among highly isolated populations of bog turtles, North America's smallest and most endangered freshwater turtle. In collaboration with Kyle Ashton, I am examining patterns of connectivity and gene flow among populations of the sand skink, a species endemic to highly fragmented patches of Florida scrub in peninsular Florida.
Alternative mating strategies in Uta stansburiana In collaboration with Barry Sinervo (UC Santa Cruz), I completed a paternity analysis in a lizard population exhibiting three alternative male mating strategies. The Sinervo lab has worked extensively on one population of the side-blotched lizard (Uta stansburiana) over the last 10 years and has detailed records on the demographics of the population as well as behaviors exhibited by males adopting each strategy.	Uta stansburiana: orange, blue, and yellow males Photo: B. Sinervo
Three throat-color and behavioral morphs are present in this population: aggressive and territorial males with orange throats, mate-guarding territorial blue-throated males, and non-territorial yellow-throated males that mimic females and "sneak" copulations by making forays into territories of the other two male morphs. Behavioral observations suggest that each strategy has strengths that allow it to outcompete one morph, and weaknesses that leave it vulnerable to another. Orange-throated males maintain large territories but are cuckolded by yellow-throated "sneaker" males. Blue-throated males avoid cuckoldry by mate-guarding but are overpowered by aggressive orange-throated males. I cloned microsatellite loci specifically for Uta stansburiana from this population to estimate paternity for all offspring at the site. These data were then used to determine the fitness of these three strategies and explore how they succeed when in direct competition with one another. We found that the rates of paternity in this population support these behavioral observations: blue-throated males (mate-guarders) are often the single sire of a female's clutch, whereas yellow-throated males tend to share paternity within a female's clutch, usually with an orange-throated male. In addition, we found that male competition is not restricted to copulation success: "sneaker" males sire more offspring posthumously, indicating that sperm competition is an important component of their strategy. These findings are very exciting, and are one of the first genetic tests of the reproductive success of males adopting alternative mating strategies

Back to KZ Home