Phone: 408-551-3000 x 6144
Room number: Alumni Science 234
B.S. 1996 University of Illinois
M.S. 2002 Oregon State University
Ph.D. 2006 Carleton University
Postdoctoral Research 2007-2009 Spanish Ministry of Education & Science, Universidad de Vigo, Pontevedra, Spain
Bio 23 Investigations in Evolution & Ecology
Bio 150 Conservation Biology
Bio 156 General Ecology
link to my full CV
I am generally interested in the origins and maintenance of diversity. My past and current projects investigate a variety of factors that contribute to this diversity, from spatial and mechanical isolation, through life history evolution and reproductive ecology to behavioral ecology and communication. I explore these phenomena using both empirical and theoretical approaches. I have predominantly worked with insects in my field research, with a special emphasis on dragonflies and damselflies (Insecta: Odonata). I have also utilized 'virtual' organisms, studying computer-generated populations under selection by human 'predators'. Following are brief descriptions of some of my current projects.
The evolution of warning signals and mimicry in multispecies systems
My Doctoral research considered the evolution of warning signals and the related phenomenon of Müllerian mimicry, exploring how conspicuous warning signals may have evolved, as well as how these signals are maintained. Through a novel technique, using human "predators" foraging for computer-generated "prey", I was able to explore these phenomena at scales that are intractable to study in the field (large numbers of individuals in a population, large numbers of prey species, many generations). My colleagues and I have explored the fate of rare conspicuous mutants in these systems(1), the affect of aggregation on the evolution of conspicuous warning signals(2) and the selection pressures for signal convergence (Müllerian mimicry) when there are few or many different prey types(3). We have consistently found that the reliability of the signal (the degree to which it is uniquely associated with unprofitability)(4) has a great impact on the evolution of the warning signal. In conjunction with Dr. Dan Franks at the University of York in the UK, I am continuing to develop these simulation models, exploring the interplay between Batesian and Müllerian mimics in complex systems.
Sex-ratio distortion and speciation in endemic island damselflies
In collaboration with an international team of colleagues, I am studying the damselflies of the genus Nesobasis, which are endemic to the islands of Fiji. This group is unique among island damselflies in that it is quite diverse (21 described species, with at least 12 undescribed species, the largest known radiation of oceanic zygopterans) and offers an opportunity to ask some fascinating questions about the evolution of behavior and sex, as well as questions concerning the process of speciation itself. Previous researchers had suggested that several of these species had extremely female-biased sex-ratios at oviposition sites and that individuals in these species demonstrated sex-role reversal, with females defending territories(5,6). photo courtesy of H. Van Gossum
In research funded by a National Geographic Society Exploration Grant, we discovered that, while females in these species are not territorial, sex ratios are indeed quite divergent between species(7,8). Some species of Nesobasis are male-biased in the adult stage, while others are female-biased, a condition which is at odds with damselfly populations throughout the world. We have found that these damselflies are infected with strains of Wolbachia, a bacterium known to skew sex-ratios in some arthropods through killing or feminizing males(9,10). Wolbachia has also been suggested to promote host speciation in some groups through cytoplasmic incompatibility(11), which opens the possibility that its presence has contributed to the large radiation in Nesobasis. We have recently developed the first molecular phylogeny of this genus and can now explore the relationship between species with differing sex ratios and Wolbachia infection rates, as well as species groups within and between islands, to begin to understand the patterns of Nesobasis speciation.
Future research (supported by a grant from the Spanish Ministry of Science and Innovation) will involve the analysis of prezygotic isolation mechanisms and the relative influence of natural and sexual selection in the species radiation of Nesobasis. Through the use of a new methodology of three-dimensional analysis of male and female mating structures(12) we will explore how morphological structures, inter-island dispersal and behavior have resulted in the complex pattern of speciation in this group.
Batesian mimicry in tropical damselflies
In 2008 I began an exciting new project, which allows me to fully combine my expertise in warning signal evolution and damselfly behavioral ecology. Supported by a grant from the Spanish Ministry of Education and Science, I and colleagues are investigating coloration in damselflies of the genus Polythore, found in Peru, Ecuador and Brazil(13). It has been suggested by several biologists that these damselflies resemble unpalatable Heliconius and Ithomiine butterflies in the region(14,15), and as such may be the first known example of Batesian mimics in damselflies. While this phenomenon has been recognized anecdotally, it has never been formally studied. Currently, there are twenty described species in this genus, which are identified predominantly by differences in wing coloration.
We are studying the geographic distribution of these species in several locations throughout Peru, correlating the distribution of Polythore species to those of different forms of Heliconius and Ithomiine butterflies, which are known to form mimicry rings. In conjunction with these biogeographical studies, are developing a molecular phylogeny of this genus to determine if the species currently described in fact represent different color morphs of the same species, taking part in different mimicry rings in different regions. This mimicry is reported to be at its most effective when the damselflies are in flight; we are also studying the colors and patterns generated when these damselflies are in motion, through spectrophotometric and video analysis.
REFERENCES:1. Sherratt, T. N. & Beatty, C.D. 2003. American Naturalist 162: 377-389; 2. Beatty, C. D., R. S. Bain and T. N. Sherratt 2005. Animal Behaviour 70: 199-208; 3. Beatty, C. D., K. Beirinckx and T. N. Sherratt 2004. Nature 431 (7004): 63-66; 4. Sherratt, T. N. 2002. Proceedings of the Royal Society of London B 269: 741-746; 5. Donnelly, T.W. 1990. New Zealand Journal of Zoology 17: 87-117; 6. Donnelly, T.W. 1994. Argia 5: 4-7; 7. H. Van Gossum, C. D. Beatty, et al. 2007. Journal of Tropical Ecology 23(5): 591-598; 8. Beatty, C. D., H. Van Gossum & T. N. Sherratt 2007. Odonatologica 36(1): 13-26; 9. Jiggins, F. M., Hurst, G. D. D. & Majerus, M. E. N. 2000. Proceedings of the Royal Society of London B 267: 69-73; 10. Charlat, S., Hurst, G. D. D. & Mercot H. 2003. Trends in Genetics 19: 217-223; 11. Telschow A., Hammerstein P. & Werren, J. H. 2005. Evolution 59(8): 1607-1619; 12. McPeek M.A., Shen L., Torrey J.Z. & Farid H. 2008. American Naturalist 171(5): E158-E178; 13. Bick, G. H. & J. C. Bick 1986. Odonatologica 15(3): 245-273; 14. Beccaloni, G. W. 1997. Tropical Lepidoptera 8(2): 103-124; 15. Silsby, J. 2001. Dragonflies of the World. CSIRO Publishing, USA. 256 pp.
T. N. Sherratt & C. D. Beatty 2003. The evolution of warning signals as reliable indicators of prey defense. The American Naturalist 162(4): 377-389. (featured in a News & Views article in Nature and an editor's review in American Entomologist)
T. N. Sherratt, A. Rashed & C. D. Beatty 2004. The evolution of locomotory behaviour in profitable and unprofitable simulated prey. Oecologia 138: 143-150.
C. D. Beatty, K. Beirinck & T. N. Sherratt 2004. The evolution of müllerian mimicry in multispecies communities. Nature 431(7004): 63-66.
C. D. Beatty, R. S. Bain & T. N. Sherratt 2005. The evolution of aggregation in profitable and unprofitable prey. Animal Behaviour 70: 199-208.
T. N. Sherratt & C. D. Beatty 2005. Island of the Clones. Nature 435(7045): 1039-1040.
T. N. Sherratt, A. Rashed & C. D. Beatty 2005. Hiding in Plain Sight. Trends in Ecology and Evolution 20(8): 414-416.
A. Rashed, C. D. Beatty, M. R. Forbes & T. N. Sherratt 2005. Prey selection by dragonflies in relation to prey size and wasp-like colours and patterns. Animal Behaviour 70: 1195?1202.
H. Van Gossum, C. D. Beatty & T. N. Sherratt 2006. The Zygoptera of Viti Levu and Vanua Levu, the two larger islands in the Fiji archipelago. IDF-Report 9: 1-14.
C. D. Beatty, H. Van Gossum & T. N. Sherratt 2007. Nesobasis species diversity and abundance: notes on an endemic damselfly genus of the Island group of Fiji (Zygoptera: Coenagrionidae). Odonatologica 36(1): 13-26
H. Van Gossum, C. D. Beatty, S. Charlat, H. Waqa, T. Markwell, J. H. Skevington, M. Tuiwawa & T. N. Sherratt 2007. Male rarity and putative sex-role reversal in Fijian damselflies (Odonata). Journal of Tropical Ecology 23(5): 591-598.
H. Van Gossum, C. D. Beatty, M. Tokota´a & T. N. Sherratt 2008. The Fijian Nesobasis: A further examination of species diversity and abundance (Odonata: Zygoptera). Odonatologica 37(3): 235-245.
M.O. Lorenzo Carballa, C.D. Beatty, C. Utzeri, V. Vieira & A. Cordero Rivera. 2010. Parthenogenetic Ischnura hastata populations in the Azores revisited: present status and notes on biology, behaviour and population ecology. International Journal of Odonatology (in press).
C. D. Beatty, S. Fraser, F. Pérez-Jvostov & T. N. Sherratt 2010. Dragonfly and Damselfly (Insecta: Odonata) Distributions in Ontario, Canada: Investigating the Influence of Climate Change. In. J. Ott (ed.) Monitoring Climate Change with Dragonflies, Pensoft Publishers (in press).
M.O. Lorenzo Carballa, C. D. Beatty & A. Cordero Rivera 2010. Parthenogenesis in island insects - the case study of Ischnura hastata. In: Terrestrial Arthropods of Macaronesia ? biodiversity, ecology and evolution. (M. Boieiro & A. Serrano eds.) (in press).