title: Hydrocarbon divergence and reproductive isolation in Timema stick insects.
abstract: BACKGROUND
  Individuals commonly prefer certain trait values over others when choosing their mates. If such preferences diverge between populations, they can generate behavioral reproductive isolation and thereby contribute to speciation. Reproductive isolation in insects often involves chemical communication, and cuticular hydrocarbons, in particular, serve as mate recognition signals in many species. We combined data on female cuticular hydrocarbons, interspecific mating propensity, and phylogenetics to evaluate the role of cuticular hydrocarbons in diversification of Timema walking-sticks.
  
  
  RESULTS
  Hydrocarbon profiles differed substantially among the nine analyzed species, as well as between partially reproductively-isolated T. cristinae populations adapted to different host plants. In no-choice trials, mating was more likely between species with similar than divergent hydrocarbon profiles, even after correcting for genetic divergences. The macroevolution of hydrocarbon profiles, along a Timema species phylogeny, fits best with a punctuated model of phenotypic change concentrated around speciation events, consistent with change driven by selection during the evolution of reproductive isolation.
  
  
  CONCLUSIONS
  Altogether, our data indicate that cuticular hydrocarbon profiles vary among Timema species and populations, and that most evolutionary change in hydrocarbon profiles occurs in association with speciation events. Similarities in hydrocarbon profiles between species are correlated with interspecific mating propensities, suggesting a role for cuticular hydrocarbon profiles in mate choice and speciation in the genus Timema.
authors.affiliation: Center for Ecological and Evolutionary Studies, University of Groningen, Groningen, The Netherlands. tanja.schwander@unil.ch
authors.forename: Tanja
authors.initials: T
authors.lastname: Schwander
authors.forename: Devin
authors.initials: D
authors.lastname: Arbuthnott
authors.forename: Regine
authors.initials: R
authors.lastname: Gries
authors.forename: Gerhard
authors.initials: G
authors.lastname: Gries
authors.forename: Patrik
authors.initials: P
authors.lastname: Nosil
authors.forename: Bernard J
authors.initials: BJ
authors.lastname: Crespi
mesh_terms: D000818:Animals; D005260:Female; D006838:Hydrocarbons / Q000032:analysis / Q000378:metabolism*; D007313:Insecta / Q000737:chemistry / Q000145:classification / Q000235:genetics* / Q000502:physiology; D008297:Male; D010641:Phenotype; D010802:Phylogeny; D060047:Reproductive Isolation; D012641:Selection, Genetic; D012726:Sexual Behavior, Animal
chemical_list: D006838:Hydrocarbons