Signals of 11 species in the E. binotata species complex. While similar in structure, signals differ in traits important for mate choice, including pitch and duration.
What role do communication systems play in assortative mating between diverging populations? And how do the ecological changes that accompany diversification shape the communication systems used in mating and other social interactions? The Enchenopa binotata species complex of treehoppers is one of the most widely cited examples of sympatric speciation in plant-feeding insects. The eleven species in this clade are host plant specialists that may have diversified as a consequence of changes in host use.
We have been investigating the patterns and processes of divergence in mating signals in the E. binotata complex, focusing on the consequences of signal evolution for assortative mating and sympatric divergence. Our approaches include comparative behavioral studies of signals, preferences, and mating systems; investigation of how signaling environments differ among host plants; ecological experiments to assess local adaptation and developmental plasticity; and molecular phylogeny and phylogeography to estimate species relationships and the evolutionary history of host plant shifts. This research was initiated in collaboration with the late Tom Wood and continues in collaboration with Rafa Rodriguez (University of Wisconsin-Milwaukee).
Publications:
Cocroft, RB & Sullivan-Beckers, LE. 2012. Female preference functions provide a window into cognition, the evolution of communication, and speciation in plant-feeding insects. In J. Vonk & T. Shackleford (eds.), Oxford Handbook of Comparative Evolutionary Psychology, pp. 339-355. Oxford: Oxford University Press. (pdf)
Rodríguez, RL, Haen, C, Cocroft, RB & Fowler-Finn, KD. 2012. Males adjust signaling effort based on female mate preference cues. Behavioral Ecology. 23: 1218-1225. doi: 10.1093/beheco/ars105 (pdf)
Sullivan Beckers, LE & Cocroft, RB. 2010. The importance of female choice, male-male competition and signal transmission as causes of selection on male mating signals. Evolution 64:3158-3171. (pdf)
Cocroft, RB, Rodriguez, RL & Hunt, RE. 2010. Host shifts and signal divergence: mating signals covary with host use in a complex of specialized plant-feeding insects. Biological Journal of the Linnean Society. 99: 60–72. (pdf)
Holan, SH, Wikle, CK, Sullivan Beckers, LE & Cocroft, RB. 2010. Modeling complex phenotypes: Generalized linear models using spectrogram predictors of animal communication signals. Biometrics 66: 914-924. (pdf)
McNett, GD & Cocroft, RB. 2008. Host shifts favor vibrational signal divergence in Enchenopa binotata treehoppers. Behavioral Ecology 19:650-656. (pdf)
Rodriguez, RL, Sullivan LM, Snyder RL & Cocroft, RB. 2008. Host shifts and the beginning of signal divergence. Evolution 62:12-20. (pdf)
Cocroft, RB, Rodriguez, RL & Hunt, RE. 2008. Host shifts, the evolution of communication and speciation in the Enchenopa binotata species complex of treehoppers. Pp. 88-100 in: Tilmon, KJ (ed.), Specialization, Speciation and Radiation: The Evolutionary Biology of Herbivorous Insects. University of California Press, Berkeley, CA. (pdf)
Rodriguez, RL & Cocroft, RB. 2006. Divergence in female duetting signals in the Enchenopa binotata species complex of treehoppers (Hemiptera: Membracidae). Ethology 112:1231–1238. (pdf)
Rodríguez, RL, Ramaswamy, K & Cocroft, RB. 2006. Evidence that female preferences have shaped male signal evolution in a clade of specialized plant-feeding insects. Proceedings of the Royal Society B 273:2585-2593. (pdf)
Rodríguez, RL, Sullivan, L, & Cocroft, RB. 2004. Vibrational communication and reproductive isolation in the Enchenopa binotata species complex of treehoppers. Evolution 58:571-578. (pdf)
Sattman, DA & Cocroft, RB. 2003. Phenotypic plasticity and repeatability in signals of Enchenopa treehoppers, with implications for gene flow among host-shifted populations. Ethology 109:981-994. (pdf)
Collaborations:
Dr. Rafael Rodriguez, University of Wisconsin-Milwaukee
Dr. Randy Hunt, University of Indiana-Southeast
Dr. Tom Wood (d), University of Delaware