• Microcebus cf myoxinus;
  • spatial distribution;
  • mating system;
  • sexual size dimorphism;
  • sperm competition


According to current hypotheses on the evolution of life history traits and social systems of Malagasy lemurs, nocturnality is associated with a solitary lifestyle and a polygynous or promiscuous mating system. Recent studies, however, have indicated that this may not be true of all lemurs. The goal of this study was to investigate the sociality and the mating system of pygmy mouse lemurs (Microcebus cf myoxinus), which are the smallest known primates, and which retain characteristics of the most primitive primates. I compared my findings with data on the sympatric Microcebus murinus and Cheirogaleus medius. Observational, morphometric and spatial distribution data were obtained by a radiotracking study in 1994, and from a capture–recapture study conducted during 1995/96. Pygmy mouse lemurs usually slept alone in a tangle of vegetation. During the mating season, sleeping sites of males were distributed over a much broader area than were female sites, indicating that male home ranges are larger than those of females. The home ranges of males overlapped during the mating season, and males occasionally roamed over long distances during a single night. Pygmy mouse lemurs forage primarily alone. Analysis of estrus stages indicate that female cycles are unsynchronized during the mating season. There was a lack of sexual dimorphism in body size but not in body mass. Males were heavier than females during the reproductive season but lighter than females the rest of the year. Testes of males varied in size seasonally and enlarged significantly during the mating season. The presence of a vaginal sperm plug in a female indicated the importance of preventing additional matings in this species. Thus pygmy mouse lemurs follow the predictions derived from sexual selection theory for multi-male mating systems with promiscuous matings and male sperm competition. Am. J. Primatol. 51:41–60, 2000. © 2000 Wiley-Liss, Inc.