Genetic and behavioural evidence of monogamy in a mammal, Kirk's dik–dik (;Madoqua kirkii)

Abstract

SUMMARYLittle is known about the mating behaviour of monogamous mammals. Here, we present behavioural and genetic evidence of fidelity in a socially monogamous dwarf antelope, Kirk's dik-dik. DNA microsatellite analysis revealed no evidence of extra-pair paternity (EPP) in dik-diks : mothers' partners matched the paternal genotype in all 12 juveniles tested. One likely reason for the absence of EPP is that males guard their mates closely during oestrus and over-mark all female scent, thereby reducing the likelihood of other males attempting to mate. In addition, males may be limited in their ability to search for extra-pair copulations (EPCs) by activities associated with pair-bond maintenance. Year-round, males maintained proximity within pairs, followed their females' activity patterns, and spent approximately 64 % of their time with their partners. However, males did attempt to obtain EPCs when the opportunity arose, and genetic monogamy in dik-diks is probably best explained by the behaviour of females : in contrast to many monogamous female birds, female dik-diks do not appear to seek EPC partners. We propose that females avoid extra-pair males because they are unable to mate with them without instigating a potentially dangerous conflict.

Evidence for high rates of in-pair paternity in the socially monogamous snapping shrimp Alpheus angulosus

“…On the other hand, empirical investigations of other socially monogamous taxa have sometimes revealed a strong overlap between social and parental monogamy, which may result from constraints that limit opportunities for EPCs (Brotherton et al 1997, Gardner et al 2002. In snapping shrimp, it appears that a large majority of embryos are the result of in-pair matings, and therefore that, at least in terms of the overall proportions of offspring sired by females' social partners, social monogamy may correlate closely with genetic monogamy.…”

“…However, social monogamy has been documented in a broad range of taxa (reviewed in Mathews 2002a), and is thought to have evolved in response to a number of selective pressures, such as the net fitness benefits of shared direct or indirect parental care (Gardner et al 2002), the high costs of mate-searching (Seibt & Wickler 1979, Brotherton et al 1997, and a net fitness benefit which may result from sharing a territory (Mathews 2002a). In such cases, both males and females should be under selection to engage in extrapair copulations (EPCs) whenever there is a net fitness benefit for doing so.…”

Correlates of genetic monogamy in socially monogamous mammals: insights from Azara's owl monkeys

“…For example, male Kirk's dik-diks do not seem to provide much infant care, but have been described as genetically monogamous [26], and fat-tailed dwarf lemurs have nearly 50% EPP rates but still show male care. It is possible that the influence of pair bonds and infant care are affected at different levels of influence in these species.…”

“…In not being committed to parental investment through pregnancy and lactation, males may enhance their reproductive success through extra-pair copulations without increasing their parental investment [12]. Still, a small but significant number of mammal species are socially monogamous [24] and genetic monogamy has been reported for four species, the California mouse (Peromyscus californicus) [25], Kirk's dik-dik (Madoqua kirkii) [26], the Malagasy giant jumping rat (Hypogeomys antimena) [27], as well as for packliving coyotes (Canis latrans) [28]. However, several other pair-living species have shown high EPP rates.…”

Female space use is the best predictor of monogamy in mammals

“…We use this de¢nition because genetic evidence for mating exclusivity is rare in mammals. Extrapair copulations have been observed in up to six monogamous species, but no extra-pair paternities were found in the three species for which genetic evidence of monogamy exists (Brotherton et al 1997). We use the term`paternal care' …”