Gender trading in a hermaphrodite

(2005). Social experience and pheromonal perception can change male-male interactions in Drosophila melanogaster. (2002). Novel genes expressed in subsets of chemosensory sensilla on the front legs of male Drosophila melanogaster. experience and their interaction on the courtship behaviour of transgenic Drosophila males. (1988). Precise characterization of cuticular compounds in young Drosophila by mass-spectrometry. Dominance hierarchy and reproductive conflicts among subordinates in a monogynous queenless ant. neuroendocrine consequences of social subjugation across adolescence and adulthood. Front. Current Biology Vol 15 No 19 R792 Figure 2. Exposure to adult cuticular hydrocarbons induces courtship dominance in B42 flies. The figure shows the percentage of B42 males displaying courtship dominance following social interactions with a range of male types (n > 25 in all cases). B42 males were housed at age 0–24 hours with adult males of varying genotypes and conditions. Data for dominance intensity (BIs) are not presented; there were no significant differences between dominant and non-dominant males for this measure. B42 and Dijon, males that predominantly produce 7-tricosene; Tai, males that predominantly produce 7-penta-cosene; Desat, males that produce no unsaturated cuticular hydrocarbons. Flies marked ** were Desat flies carrying the cuticular profile typical of the strain marked between the asterisks, following hydrocarbon transfer between live flies. Hydrocarbon transfer took place for 24 hours at three days old (at this age, differential dominance can not be induced). HL, headless. Bars are coded according to the hydrocarbon profile of the Although males and females may face severe sexual conflicts [1], the decision over who donates and who receives sperm is fixed. This is not necessarily the case in simultaneous hermaphrodites, where each mate may insist on copulating as 'male,' 'female' or both. The resulting conflicts over gender provide an opportunity to study conflict-solving strategies. By directly manipulating mating interests in the sea slug Chelidonura hirundinina, we present the first unequivocal evidence for 'sperm trading' [2], a mating strategy where sperm donation is conditional on sperm receipt. Trading enforces reciprocity, offering a simple solution for the gender conflict. Following its original description in 1984 [2], sperm trading has been suggested to be widespread as many hermaphrodites inseminate reciprocally. But recent studies have shown that reciprocity alone does not prove sperm trading [3,4]. Showing that bidirectional sperm exchange is indeed conditional requires experimental manipulation of sex roles, which is impractical in most species studied thus far [5–7]. Hermaphroditic sea slugs of the Order Cephalaspidea are exceptional …