title: Evidence for the circadian gene period as a proximate mechanism of protandry in a pollinating fig wasp.
abstract: Protandry in insects is the tendency for adult males to emerge before females and usually results from intra-sexual selection. However, the genetic basis of this common phenomenon is poorly understood. Pollinating fig wasp (Agaonidae) larvae develop in galled flowers within the enclosed inflorescences ('figs') of fig trees. Upon emergence, males locate and mate with the still galled females. After mating, males release females from their galls to enable dispersal. Females cannot exit galls or disperse from a fig without male assistance. We sampled male and female Ceratosolen solmsi (the pollinator of Ficus hispida) every 3 h over a 24 h emergence period, and then measured the expression of five circadian genes: period (per), clock (clk), cycle (cyc), pigment-dispersing factor (pdf) and clockwork orange (cwo). We found significant male-biased sexual dimorphism in the expression of all five genes. per showed the greatest divergence between the sexes and was the only gene rhythmically expressed. Expression of per correlated closely with emergence rates at specific time intervals in both male and female wasps. We suggest that this rhythmical expression of per may be a proximate mechanism of protandry in this species.
authors.affiliation: Key Laboratory of Zoological Systematics and Evolution, Institute of Zoology, Chinese Academy of Sciences, , Beijing 100101, People's Republic of China.
authors.forename: Hai-Feng
authors.initials: HF
authors.lastname: Gu
authors.forename: Jin-Hua
authors.initials: JH
authors.lastname: Xiao
authors.forename: Derek W
authors.initials: DW
authors.lastname: Dunn
authors.forename: Li-Ming
authors.initials: LM
authors.lastname: Niu
authors.forename: Bo
authors.initials: B
authors.lastname: Wang
authors.forename: Ling-Yi
authors.initials: LY
authors.lastname: Jia
authors.forename: Da-Wei
authors.initials: DW
authors.lastname: Huang
mesh_terms: D000818:Animals; D002681:China; D005260:Female; D005786:Gene Expression Regulation; D019476:Insect Proteins / Q000235:genetics* / Q000378:metabolism; D008297:Male; D008969:Molecular Sequence Data; D056950:Period Circadian Proteins / Q000235:genetics* / Q000378:metabolism; D060888:Real-Time Polymerase Chain Reaction; D012098:Reproduction; D017422:Sequence Analysis, DNA; D012727:Sex Characteristics; D014863:Wasps / Q000235:genetics / Q000502:physiology*
chemical_list: D019476:Insect Proteins; D056950:Period Circadian Proteins
keywords: circadian clock; eclosion; mutualism system; sexual selection