Partial brood release in woodlice: A bet-hedging tactic?

No Abstrac

Mating behaviour and mate choice experiments in some tropical millipedes (Diplopoda: Spirostreptidae)

Single and multiple choice mating experiments were conducted using individuals of six species of spirostreptid millipede collected from five separate localities in Zimbabwe. Mating behaviour and copulation duration were recorded. In three of the species between-population comparisons were made. The most common copulatory behaviour was highly physical with the male coiled tightly around the female. In one species (Calostreptus sp.) the sexes copulated in parallel with no overt physical manoeuvring by the male. This species also had the shortest copulation duration. In single choice experiments random mating was assumed when mating frequency was independent of male body mass. This occurred in both populations of Cabstreptus sp., Spinotarsus sp. 1 and one of the populations of Albporus uncinatus. In four cases there was a significant positive relationship between mating frequency and body mass. Only three populations mated randomly in the multiple choice experiments. In two populations mating was random in single choice and non-random in multiple choice experiments and the reverse occurred in one population of Odontopyge sp. 3. The implications of these results are discussed in relation to processes of male-male competition and female choice

Males control the duration of copulation in the tropical millipede Alloporus uncinatus (Diplopoda: Julida)

Prolonged copulation in Alloporus uncinatus is a form of mate guarding against sperm competition. Here we show, using a simple experiment, that males control the duration of copulation, an often overlooked assumption regarding the adaptive significance of prolonged copulation. The sex-specific evolutionary benefits of prolonged copulation are discussed in relation to the role played by sperm competition in the evolution of the mating system of A. uncinatus