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1.  How does breeding system variation modulate sexual antagonism? 
Biology Letters  2009;5(5):717-720.
The study of sexually antagonistic (SA) traits remains largely limited to dioecious (separate sex), mobile animals. However, the occurrence of sexual conflict is restricted neither by breeding system (the mode of sexual reproduction, e.g. dioecy or hermaphroditism) nor by sessility. Here, we synthesize how variation in breeding system can affect the evolution and expression of intra- and inter-locus sexual conflicts in plants and animals. We predict that, in hermaphrodites, SA traits will (i) display lower levels of polymorphism; (ii) respond more quickly to selection; and (iii) involve unique forms of interlocus conflict over sex allocation, mating roles and selfing rates. Explicit modelling and empirical tests in a broader range of breeding systems are necessary to obtain a general understanding of the evolution of SA traits.
PMCID: PMC2781973  PMID: 19553248
sexual conflict; sex allocation; selfing; sex chromosomes; simultaneous hermaphroditism; dioecy
2.  Accessory male investment can undermine the evolutionary stability of simultaneous hermaphroditism 
Biology Letters  2009;5(5):709-712.
Sex allocation (SA) models are traditionally based on the implicit assumption that hermaphroditism must meet criteria that make it stable against transition to dioecy. This, however, puts serious constraints on the adaptive values that SA can attain. A transition to gonochorism may, however, be impossible in many systems and therefore realized SA in hermaphrodites may not be limited by conditions that guarantee stability against dioecy. We here relax these conditions and explore how sexual selection on male accessory investments (e.g. a penis) that offer a paternity benefit affects the evolutionary stable strategy SA in outcrossing, simultaneous hermaphrodites. Across much of the parameter space, our model predicts male allocations well above 50 per cent. These predictions can help to explain apparently ‘maladaptive’ hermaphrodite systems.
PMCID: PMC2781950  PMID: 19605385
simultaneous hermaphroditism; sex allocation; sexual selection; male copulatory organ; adaptiveness; sexual antagonism
3.  Precopulatory stabbing, hypodermic injections and unilateral copulations in a hermaphroditic sea slug 
Biology Letters  2007;3(2):121-124.
Reciprocity constitutes the prevalent mating mechanism among simultaneous hermaphrodites. Yet, when copulations in the female role confer fitness costs through male manipulation, it becomes advantageous sometimes to mate unilaterally in the male role only. In the sea slug Siphopteron quadrispinosum, acting males stab their partner with a bipartite penis, which not only hypodermically injects prostate fluids, but also apparently mechanically enforces unilateral male matings. Despite a pronounced male mating drive in both partners, unilaterality ensued when one slug stabbed more rapidly than its partner. The acting male may thus avoid the costs inflicted by traumatic injections and penial spines. While future studies need to elucidate the net fitness consequences of stabbing, our behavioural evidence is in line with the hypothesis that mating in S. quadrispinosum represents conflicting rather than complementary mating interests between mates.
PMCID: PMC2375930  PMID: 17251120
hermaphroditism; sexual conflict; Siphopteron quadrispinosum

Results 1-3 (3)