Cryptic polyandry overt sperm competition

The phenotypic expression of traits subject to intense sexual selection via female choice can evolve condition dependence, providing honest signals of the underlying genetic quality of potential mates [ 40 , , ]. Using factorial North Carolina II type breeding design experiments [ 25 ], p. Through experimentally controlled natural matings, we confirm that selection against related males' sperm occurs within the female reproductive tract but demonstrate that this is more accurately predicted by MHC similarity: Indeed, we see considerable phenotypic plasticity within species, with males investing in mate guarding more heavily when the risk of sperm competition is high. On top of the difficulties in isolating evidence for indirect polyandry benefits, are the challenges in identifying the controlling processes that might allow such benefits to be gained, and whether they arise through specific sperm—egg interactions, or by mechanisms controlled by the female reproductive tract. Results Following paired comparisons of offspring generated from up to 21 versus 21 eggs from up to 24 females and 16 males, we find that offspring fitness was almost identical between treatment groups that had been fertilized in the presence versus absence of opportunities for sperm competition and cryptic female choice. Nonetheless, where the benefits of mating exceed these costs, so that females have positive Bateman gradients, selection is expected to favour the evolution of polyandry.

Reproductive benefits from female promiscuous mating in a small mammal. Whales can be found in polar, temperate, and tropical waters, both near shore and in the open ocean, and from the water's surface to depths of over 1 kilometer. The Animal Diversity Web follows this revised classification. We do not consider sexual differences i. In these cases, males provide at least some care to their offspring. Apfelbach, ; Vaughan, et al.

Gestation in eutherians is metabolically expensive. Reichholf, b ; Vaughan, et al. Like social insects Hymenoptera and Isoptera , naked mole rats are eusocial, with a queen female mating with several males and bearing all of the young in the colony. Many mammals are seasonal breeders, with environmental stimuli such as day length, resource intake and temperature dictating when mating occurs. Negative Some mammal species are considered to have a detrimental impact on human interests.