Inferences from Strepsirrhine Primates

The hypothesis that ancestral primates lived in dispersed harem systems has recently been rejected on the basis of new data on cheirogaleid and lorisiform social organization (Müller and Thalmann, 2000). If it is assumed that cheirogaleids and lorisiforms approach the ancestral primate condition most closely and that the pattern of social organization that is found most frequently in those two groups is most likely to be representative of the first primates, the hypothesis of a dispersed harem system representing the ancestral primate condition can indeed not be upheld. No cheirogaleid species studied so far exhibits a dispersed harem system. Mirza coquereli as well as Microcebus murinus, M. ravelobensis and presumably M. rufus, and M. berthae (see Rasoloarison et al., 2000) exhibit dispersed multimale/multifemale systems (Atsalis, 2000; Ehresmann, 2000; Fietz, 1999a; Kappeler, 1997b; Radespiel, 2000; Schwab, 2000), whereas Cheirogaleus medius and Phaner furcifer live in dispersed monogamous family groups (Charles-Dominique and Petter, 1980; Fietz, 1999b; Fietz et al., 2000; Müller 1998, 1999a,b; Schülke and Kappeler, 2003). There are as yet no data on the social organization of the remaining cheirogaleid species.

A reevaluation and reinterpretation of the patterns of social organization in bushbabies and lorises revealed that, with the possible exception of Galago alleni, none of the species exhibit a dispersed harem system. Instead, these species are most likely to exhibit dispersed multimale/multifemale systems (Müller and Thalmann, 2000). Bushbaby males generally have bigger home ranges than females, and the females are associated in matriarchies. The females of one group are usually aggressive toward females of another group and the males are often aggressive toward other males (Bearder and Doyle, 1974; Bearder and Martin, 1980; Bearder, 1987; Charles-Dominique, 1974, 1977). In Galagoides demidoff and Galago moholi, males have been divided into A and B males. The home range of an A male overlaps the range of one or more female groups, but other males have at least spatial access to those females as well (Bearder and Martin, 1980; Charles-Dominique, 1972, 1977; Pullen et al., 2000). In fact, Pullen et al., (2000) observed that G. moholi females copulated with more than one male. In Otolemur crassicaudatus and O. garnettii, an adult male overlaps only one female association but again, the females have access to more than one male (Bearder, 1987; Clark, 1985; Doyle and Bearder, 1977; Nash and Harcourt, 1986). By contrast, Galagoides zanzibaricus is organized in dispersed monogamous groups (Harcourt and Nash, 1986a). Data on lorisid social organization are very limited (Müller and Thalmann, 2000) but the Asian slender loris (Loris tardi-gradus) has been reported to live in dispersed multimale/multifemale systems (Nekaris, 2003).

The larger solitary foragers (Daubentonia madagascariensis and Lepilemur sp.) and the gregarious lemurs do not live in harems either but in multi-male/multifemale systems or monogamously. Based on all of the above data, it was concluded that dispersed multimale/multifemale systems and dispersed monogamy are the predominant patterns of social organization found in strepsirrhine primates (Müller and Thalmann, 2000) (Figure 1). A dispersed multimale/multifemale system is the most frequent pattern among strep-sirhines, but monogamy occurs almost as often, especially in lemurs. Which

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