Department of Biology
102 Myers Hall
915 East Third Street
Bloomington, IN, 47405-7107
Phone: (812) 856-1783
NIH-post doctoral fellow
Advisor: Dr. Armin P. Moczek
Indiana University, Bloomington, IN, January 2012- current.
Post-doctoral Research Associate
Advisor: Dr. William E. Wagner Jr.
University of Nebraska, Lincoln, NE, August 2008 – December 2011.
Ph.D. in Biological Sciences (Ecology, Evolution, and Behavior)
Advisor: Dr. Johannes Schul
University of Missouri, Columbia, MO, May 2003 - August 2008.
M. S. in Biology (Ecology, Evolution, and Behavior)
Advisors: Dr. Otto von Helversen & Dr. Johannes Schul
Friedrich-Alexander University-Erlangen (Germany), November 1996 - February 2003.
The Evolution of Animal Behavior
I am fascinated by animal behavior and the factors involved in its evolution. My research has been focused on animal behavior in the context of reproduction. This field is especially interesting for evolutionary processes because any trait involved in the reproductive success of the trait-bearer influences whether his/her genes are passed on to the the next generation and thus how the population diversifies or even diverges into new species. I have primarily investigated acoustic communication used by frogs, katydids, crickets and their eavesdropping parasitoid fly. My research so far has covered the impact of phenotypic plasticity, natural selection by eavesdropping parasitoids, sexual selection by female choice, mate assessment strategies on the evolution of male mating signals and female preferences for male signals. Recently, I started investigating the genetics underlying mating behavior in horned beetles. Below, I outline overviews of my research, starting at my current project.
1.) Genetic regulation of reproductive behavior in horned beetles
Behavioral and morphological traits that are important features of reproductive strategies often appear tightly co-regulated, such as antler possession and fighting behavior in deer or colorful displays and associated behaviors in many insects and birds. Such coordinated regulation of the expression of sexual morphological and behavioral traits is crucial because mismatches could severely reduce fitness (e.g. having antlers but not using them in the context of reproduction).
The dung beetle system, Onthophagus taurus, represents an emerging model system in the study of development, sexual behavior, and the regulation of sex differences. One key feature of this system is that male beetles are polyphenic in both appearance and mating behavior. Depending on larval
diet, males mature into discretely different large and horned (picture to the right) or smaller and hornless adults (picture to the left). Female body size is similarly influenced by nutrition, but in almost all species females will not develop horns and remain monomorphic. Importantly, male reproductive behavior changes in parallel with morphology: horned males engage in aggressive fight(s) over access to females, defend tunnels containing females, and engage to a much higher degree in cooperative behavior with females during brood provisioning. In contrast, small hornless males sneak copulations, are less aggressive, rely on sperm competition, and do not display cooperative behavior. Thus, these behavioral differences related to the alternative morphological phenotypes play an important role for the reproductive success of both males and females.
Recently, the regulation of morphological (horn) differences in O. taurus has been linked to the gene doublesex (dsx) (Kijimoto et al., in review). I am currently testing the hypothesis that the coordination of male horn morphology and reproductive behavior is controlled by dsx using a combination of RNA interference to down-regulate the gene product and behavioral assays to identify its effects. I am planning to investigate the effect of dsx also in females, other beetle species, and repeat the experiments with a second target gene, fruitless (fru).
2.) The significance of an eavesdropping (lethal) parasitoid on the evolution of a cricket communication system
Males of the cricket Gryllus lineaticeps produce conspicuous songs to attract females for mating and females express preferences for certain song types. Unfortunately for the cricket, the eavesdropping fly Ormia ochracea also uses the male mating songs to localize the singing male (picture to the right: fly, cricket, and fly pupa from top to bottom). After the fly lands next to the male, it expels planidial larvae on and around the cricket. Infested crickets die within 10 days. Female crickets can get parasitized too. Interestingly, the flies have the same preferences for male song types as the female crickets (i.e. they prefer faster and longer songs). Thus, from the male’s perspective, advertising his ‘sexiness’ to attract females increases the risk of getting infested by the fly. From the female’s perspective, approaching a ‘sexy’ male for mating also increases her chances of being parasitized. Thus, natural and sexual selection act in opposing directions for both male song and female preferences. I investigated with Dr. Wagner at UNL how fly parasitism has influenced the evolution of the host’s communication system using a comparative study between 6 parasitized and 6 non-parasitized populations of G. lineaticeps. Surprisingly, songs and singing activity in parasitized populations seem to have evolved primarily under the influence of sexual selection and not natural selection (Beckers & Wagner 2011c, Beckers & Wagner in preparation). The analysis of female preferences for different song types from all 12 populations is in the works. Additionally, we found that the two most preferred song characters are negatively correlated with each other, limiting the evolution of male mating songs in this species (Wagner, Beckers, Tolle, and Basolo 2012).
3.) The significance of developmental plasticity in the evolution of a katydid communication system
Communication systems typically consist of a signaler and a receiver. The female usually uses the male mating signals for species identification, mate choice, and mate approach. The male signal and female signal recognition have to be matched for the communication system to function, otherwise costly mismatings with heterospecifics are likely to occur. Consequently, signals and signal recognition are unique for each species and variation in each trait is typically low.
In contrast to the vast majority of communicating animals, males of the katydid Neoconocephalus triops (picture to the right) produce different mating songs in different seasons in North America. Males that develop during long photoperiods produce a fast summer song and males developing under short photoperiods produce a substantially slower winter song. The songs are so different that the two generations of N. triops were originally described as different species. I found that the speed of the mating song is actually the single most important song character that females use to identify the songs of their males (Beckers & Schul 2008). These findings raised the question how females recognize the songs of males in each generation. Surprisingly, summer and winter females do not differ in their preferences and prefer the same song rates. However, female preference strongly changes with ambient temperature. At low temperatures (typical for the winter generation) females prefer the slower winter song and at high temperatures (typical for the summer generation) females prefer the faster summer song (Beckers & Schul 2008), resulting in a functioning communication system despite the substantial variation. Further experiments indicated that the steep temperature dependence of female preferences has evolved to compensate for male song plasticity (Beckers & Schul 2010). Thus, male phenotypic plasticity contributed to the evolution of a female trait in an unusual way: plasticity of male songs led to the diversification of female preferences.
Beckers, O.M. and Wagner, W.E. Jr. (2013). Parasitoid infestation changes female mating preferences. Animal Behaviour 85: 791-796.
Beckers O.M. and Wagner, W.E. Jr. (2012) Eavesdropping parasitoids do not cause the evolution of less conspicuous signalling behaviour in a field cricket. Animal Behaviour 84: 1457-1462.
Kijimoto T., Pespeni M., Beckers O.M., Moczek A.P. (2012) Beetle horns and horned beetles: emerging models in developmental evolution and ecology. WIREs Interdisciplinary Reviews in Developmental Biology. DOI: 10.1002/wdev.81.
Wagner, W.E. Jr. Beckers, O.M., Tolle, A.E and Basolo, A.L. (2012). Tradeoffs limit the evolution of male traits that are attractive to females. Proceedings of the Royal Society B. 279:2899–2906.
Beckers, O.M. and Wagner, W.E. Jr. (2012). Divergent preferences for song structure in a field cricket and its phonotactic parasitoid. Journal of Insect Behavior. 25: 467–477.
Beckers, O.M., and Wagner, W.E. Jr. (2011) Male field crickets infested by parasitoid flies express phenotypes that may benefit the parasitoids. Animal Behaviour 82(5):1151-1157.
Beckers, O.M., Martin, C., and Wagner, W.E. Jr. (2011). Survival rates of planidial larvae of the parasitoid fly Ormia ochracea (Diptera: Tachinidae). Journal of the Kansas Entomological Society 84(3): 235-237.
Beckers O.M. and Wagner W.E. Jr. (2011). Mate sampling in a field cricket: evidence for a fixed threshold strategy with last chance option. Animal Behaviour 81:519-527.
Beckers O.M. and Schul J. (2010). Female adaptation to developmental plasticity of male calling behavior. Behavioral Ecology and Sociobiology 64(8): 1279-1290.
Bush S.L., Beckers O.M., and Schul J. (2009). A complex mechanism of call recognition in the katydid Neoconocephalus affinis. Journal of Experimental Biology 212: 648-655.
Beckers, O.M. and Schul J. (2008). Developmental plasticity of mating calls enables acoustic communication in diverse environments. Proceedings of the Royal Society B 275: 1243-1248.
Beckers, O.M. and Schul J. (2004). Phonotaxis in Hyla versicolor (Anura: Hylidae): the effect of absolute call amplitude. Journal of Comparative Physiology A 190: 869-876.
The Animal Behavior manuscript (Beckers & Wagner 2013) has been featured in ScienceNews, Scientific American as well as on diverse other online webpages and was featured in the radio broadcast 'Academic Minute' on WAMC Northeast Public Radio on July 3.
The Animal Behavior manuscript (Beckers & Wagner 2011) has been featured in the 'In Focus' section of the Journal.
The Carmel Valley Pine Cone, CA: 'Aided by extraordinary hearing, flies stalk mate-seeking crickets'. July 31, 2009.
The manuscript published in the Proceedings of the Royal Society (2008) was featured in national newspapers and on national and international web-pages, such as: EurekAlert (AAAS), ScienceDaily, St. Louis Post