sex will gather together to sleep. This is likely to conserve heat. Most often in a group of females, those that share a sleeping space are related, however, groups of males do not show much if any relation with those they sleep with. In addition to mutualistic sleeping behavior, these lemurs share another positive social interaction. During the mating season, males and females must come together fairly peacefully. This happens in the spring shortly after waking up from winter torpor. The males have large testes, which implies that as opposed to male-male competition in fighting, they are much more likely to undergo sperm competition which limits some of the social aspects of breeding that many other animals undergo. The male Goodman's Mouse Lemur is known to have more bodyweight than the female during the reproductive season. However, other times, how much these species weigh can vary according to the season. Phylogeny The genus Microcebus is shown to have diverged approximately ten to nine million years ago. This split allowed for greater radiation of mouse lemurs. The mouse lemurs split into three distinct clades. Goodman's mouse lemur has been grouped with five other species due to mitochondrial DNA sequencing. 540 thousand years ago M. marohita initially split from the other four mouse lemur populations within that clade. The most recent split was about 52 thousand years ago when M. lehilahytsara and M. mittermeieri became two distinct species. Correlated with the most recent speciation was a climatic change period. It has been proposed that this climate change likely would have desiccated the central highlands of Eastern Madagascar. The change in climate and habitat is likely the cause of the recent speciation. Evidence for this is that the habitat for Goodman's mouse lemur does not overlap with any other mouse lemurs. The habitat would have changed in such a way that the lemurs that would become Goodman's mouse lemur would be the only ones that could survive in that habitat. Their diet really varies from insects to fruits, flowers, nectar, gum and leaves. Not only food choices are diverse, but also their metabolism, body temperature and body mass can vary from time to time depending on the season and the conditions of the environment. References External links Two new lemur species discovered - Press release from the Chicago Field Museum Photos from ARKive. Arvedlund, M. & Nielsen, L.E. (1996) Do the anemonefish Amphiprion