Breaking the succession rule: the costs and benefits of an alpha-status take-over by an immigrant rhesus macaque on Cayo Santiago

Abstract

Explaining intraspecific variation in reproductive tactics hinges on measuring associated costs and benefits. Yet, this is difficult if alternative (purportedly less optimal) tactics remain unobserved. We describe a rare alpha-position take-over by an immigrant male rhesus macaque in a population where males typically gain rank via succession. Unusually, male aggressiveness after the take-over correlated with rank and mating success. The new alpha achieved the highest mating and reproductive success. Nevertheless, he sired only 4 infants due to high extra-group paternity (59.3%). The costs of his immigration tactic were high: after the mating season ended, unable to deter coalitionary attacks by resident males, he was overthrown. The following year he had the highest relative annual weight loss and levels of immune activation among males in the group. Succession-based rank-acquisition in large, provisioned groups of macaques thus appears to be actively maintained by resident males, who impose high costs on challengers.

Paternity in wild ring‐tailed lemurs (Lemur catta): Implications for male mating strategies

“…Extra‐group males in this study sired approximately 21–33% of offspring. This level of extra‐group paternity is comparable to that found in some other group‐living primates (i.e., langurs, Semnopithecus entellus : 21% [Launhardt et al, ], rhesus macaques, Macaca mulatta : 25–59% [Georgiev et al, ; Widdig et al, ], chimpanzees, Pan troglodytes : 0–10.5% [Boesch, Kohou, Nene, & Vigilant, ; Newton‐Fisher, Emery Thompson, Reynolds, Boesch, & Vigilant, ; Vigilant, Hofreiter, Siedel, & Boesch, ], Verreaux's sifaka, Propithecus verreauxi : 17–65% [but see Kappeler & Schaffler, ; Lawler, ; Lawler et al, ]). Thus, male visits to other groups during the breeding season (Gould, ; Sauther, ; Sussman, ) function as a viable mating strategy for L. catta males (Sauther & Sussman, ).…”

“…When compared to other primates in which paternity skew has been measured using the B index, our L. catta groups showed a broad range and some of the highest skew values calculated among multi‐male primate groups. Multi‐male primate groups often show low or intermediate skew, with >1 male siring group offspring (e.g., northern muriqui, Brachyteles hypoxanthus , B = 0.012 [Strier, Chaves, Mendes, Fagundes, & Di Fiore, ]; rhesus macaques, Macaca mulatta , B = 0.0485–0.1068 [Dubuc, Muniz, Heistermann, Engelhardt, & Widdig, ; Georgiev et al, ; Widdig et al, ]; Assamese macaques, M. assamensis , B = 0.087: [Sukmak et al, ]). Half of our groups showed similarly low skew, with values approximating (or lower than) these published values.…”

“…Similarly, in one population of langurs ( Semnopithecus entellus ), nonresident males sired 21% of the infants in multi‐male groups (Launhardt, Borries, Hardt, Epplen, & Winkler, ). Rhesus macaques, Macaca mulatta , on Cayo Santiago show extra‐group paternity rates as high as >59% in some years (Georgiev et al, ). Rates of extra‐group paternity are expected to be highest where resident males have greater difficulty monopolizing copulations with females (e.g., groups with a female‐biased sex ratio: [Lawler et al, ]).…”

Rank acquisition in rhesus macaque yearlings following permanent maternal separation: The importance of the social and physical environment

“…Finally, tenure in a social group also plays a role in rank development. For example, children that have been at a daycare longer also tend to be more dominant (Hawley & Little, ), and in rhesus monkeys, those introduced into a group earlier occupy higher ranks than those introduced later (Bernstein & Gordon, ; Snyder‐Mackler et al, ), similar to group tenure in wild primates (chimpanzees: Foerster et al, ; but see Georgiev et al, for an unusual case in male rhesus macaques). The collective results of a variety of studies thus reveal that rank acquisition is a complicated process that likely depends on a number of individual and social factors, as well as the complexity of early life experiences.…”

Alpha male replacements in nonhuman primates: Variability in processes, outcomes, and terminology

“…Alpha males may disperse if they can attain greater mating success in another group, such as joining a group with more females (e.g., C. capucinus , Jack & Fedigan, ) or fewer related females (e.g., P. cynocephalus , Alberts & Altmann, ), or when there is a female mating preference for recent immigrant males (e.g., M. mulatta , Berard, ). Succession is opportunistic in some species, occurring in a small percentage of alpha male replacements (e.g., C. capucinus , Jack et al, ) but it also occurs habitually in others like rhesus ( M. mulatta ) and Japanese macaques ( M. fuscata ), where it has also been referred to as queuing (Berard, ; Bercovitch, ; Georgiev et al, ; Kokko & Johnstone, ; Manson, ; Sprague, Suzuki, & Tsukahara, ). In these species, rank among males usually correlates with tenure in the group rather than fighting ability (Vessey & Meikle, ).…”