Pair-Bonding, Female Aggression and the Evolution of Lemur Societies

Abstract

Lemur societies have been described as convergent with those of anthropoids, including Papio-like female-bonded multi-male groups. Recent research, however, shows at least 5 pair-bonded species among the Lemuridae and Indriidae. Three more, Eulemur mongoz, Eulemur fulvus and Varecia variegata, have societies combining aspects of pairing with aspects of troop life. The best-known female-bonded societies, those of Lemur catta, Propithecus diadema edwardsi and Propithecus verreauxi, may be assemblages of mother-daughter dyads, capable of high aggression towards other females, but derived from more solitary female ancestors, perhaps also living as pairs. The internal structure of such lemur groups differs from the more extensive kin groups of catarrhines. This in turn may relate to the lemurs’ level of social intelligence and to lemur female dominance over males.

Intertemporal choice in lemurs

“…Capuchins provide an interesting comparison because, though they share similar body sizes, capuchins wait on average three times longer (almost five times longer using only the data from Addessi et al, 2011) than lemurs. Though making comparisons across phylogenetically distantly related taxa warrants caution, socio-ecological characters such as social complexity, tool use, and extractive foraging for the lemur species tested here may not be as developed as those of capuchins (Jolly, 1998;Vasey, 2003). Without these pressures, lemurs may not have evolved the ability to wait like other primate species.…”

The lemur syndrome unresolved: extreme male reproductive skew in sifakas (Propithecus verreauxi), a sexually monomorphic primate with female dominance

“…In addition, breeding competition among female lemurs is unusually intense, including targeted aggression and eviction of close relatives (Vick and Pereira 1989;Pereira and Leigh 2003). Explaining this combination of traits-the "lemur syndrome"-has long posed a challenge to evolutionary anthropologists, and several hypotheses have been proposed to explain the even sex ratio, the lack of male-biased sexual dimorphism, and the evolution of female dominance (van Schaik and Kappeler 1996;Jolly 1998;Wright 1999;Richard et al 2002). In this study, we test predictions of relevant key hypotheses for the first time with reproductive skew theory.…”

“…Thus, lemur groups contain more subordinate males than expected for the number of adult females present (see Andelman 1986). Moreover, females tend to be larger and heavier than males, and they dominate males socially (Jolly 1966;Richard 1987;Kappeler 1993). In addition, breeding competition among female lemurs is unusually intense, including targeted aggression and eviction of close relatives (Vick and Pereira 1989;Pereira and Leigh 2003).…”

Androgen levels and female social dominance inLemur catta

“…Sex has no e¡ect on the dominance relationships among juveniles, but all females begin to dominate all males during puberty in dyadic interactions (Pereira 1993). Female dominance has since been reported for several other lemur species (Kappeler 1993;Jolly 1998) where it may require female aggression in certain dyads and/or contexts. The spotted hyena (Crocuta crocuta) is the only other mammalian species in which adult females generally dominate males (Kruuk 1972;Tilson & Hamilton 1984;Frank 1996), but natal males dominate at least some females of lower ranking matrilines (Frank 1986;Frank et al 1989;Smale et al 1993).…”

“…Sexual dimorphism and male dominance over females are considered as evolutionary by-products of this type of selection (Darwin 1871;Andersson 1994). Accordingly, socalled reversed sexual dimorphism and female dominance, de¢ned as unconditional dominance of all adult females over all adult males, are unexpected and, indeed, rare among mammals (Ralls 1976;Richard 1987;Kappeler 1993;Jolly 1998). The evolutionary causes favouring such sex role reversals remain obscure (Young et al 1990;Tilden & Oftedal 1995;Kappeler 1996a).…”