Comparative morphological trade-offs between pre- and post-copulatory sexual selection in Giant hissing cockroaches (Tribe: Gromphadorhini)

Sperm competition theory predicts that animals face a trade-off between investment in weaponry and investment in ejaculate composition. Within the Madagascan giant hissing cockroaches (Tribe Gromphadorhini) differences in morphology exist that may indicate differing strategies of male-male competition. We compared relative pronotal horn length using high-resolution X-ray CT scanning data, relative testes mass, and male-male agonistic behaviour between two species of hissing cockroaches, Gromphadorhina oblongonota and Aeluropoda insignis. The gross morphology and behaviour of these two species indicated that G. oblongonota is selected for pre-copulatory mate acquisition and that A. insignis is selected for post-copulatory sperm competition. We found evidence for a trade-off when investing in testes mass vs. horn length between the species. The large, aggressive G. oblongonota follows a strategy of greater investment in weapons at the expense of testes mass while the smaller, less-aggressive A. insignis invests in relatively greater testes mass and less in pronotal weapon length. We also found evidence of a trade-off within each species, where individuals invest more heavily in weapon length at the expense of testes mass. These findings support the predictions of pre- and postcopulatory competitive investment trade-offs for a relatively understudied Tribe of cockroaches

Verification by Construction of Distributed Algorithms

International audienceThe verification of distributed algorithms is a challenge for formal techniques supported by tools, as model checkers and proof as- sistants. The difficulties, even for powerful tools, lie in the derivation of proofs of required properties, such as safety and eventuality, for dis- tributed algorithms. Verification by construction can be achieved by us- ing a formal framework in which models are constructed at different levels of abstraction; each level of abstraction is refined by the one below, and this refinement relationships is documented by an abstraction relation namely a gluing invariant. The highest levels of abstraction are used to express the required behavior in terms of the problem domain and the lowest level of abstraction corresponds to an implementation from which an efficient implementation can be derived automatically. In this paper, we describe a methodology based on the general concept of refinement and used for developing distributed algorithms satisfying a given list of safety and liveness properties. The modelling methodology is defined in the Event-B modelling language using the IDE Rodin