Where does male‐to‐male “aggression” compromise “cooperation”?

Abstract

We discussed how the diverse nature of aggression and cooperation is understandable, if we focus our attention on where aggression reaches a compromise with peace and/or cooperation in response to the relatedness between interactors. First we addressed whether the Hamilton's rule is applicable for explaining the variation of male-to-male aggressiveness. Next we showed that the variation in aggression and cooperation known in males of social spider mites (Saito 1995) is explainable from the change of relatedness (i.e. inclusive fitness) and effect of cooperative defense (synergistic effect). Then we learned there is a sufficient condition of cooperation which is determined primarily by two factors; the relatedness and synergistic effect of males. Furthermore, we expect that there is a condition where the aggression between males varies depending upon the relatedness close to the sufficient condition of cooperation. Problems focused onAnimal cooperation and aggression are two fundamental themes that have attracted numerous sociobiologists so far (Wilson 1975;Alcock 1979;Maynard Smith 1982a;Trivers 1985; Krebs and Davis 1987;Dugatkin 1997). However, both have been treated as separate phenomena to be focused on from the view of sociobiology. For example, Wilson (1975) discussed "cooperative breeding" in chapter 5 and "aggression" in the chapter 11 of his seminal book "Sociobiology". Dugatkin (1997) 's review of animal cooperation also discussed these phenomena separately, even though the game theory reasoning about cooperation with kin-ship (Hines and Maynard Smith 1979;Grafen 1979) involves a bud of new ideas to treat these phenomena inclusively.However, several doubts remain over how the increase of inclusive fitness through cooperation between relatives (kin selection) influences individual fitness through resource competition between them (individual selection), and where (and when) these two extremes compromise in group living animals (Maynard Smith 1982b;Queller 1985;West et al. 2001;Glron et al. 2004)? Such questions may be related to a tendency to start any focus on the evolution of aggression or cooperation "from neutral to highly aggressive behaviors" or "from neutral to highly cooperative ones" in group living animals, and not from aggression to cooperation. Another related problem is that interactions between individuals in the context of social evolution have been considered a priori to be phenomena in "group forming" animals, even though most animals are in a continuum from solitary to group living, and there are few animals that live "solitary" throughout their life-times (Krause and Ruxton 2002). 1We feel that such fragmentary views have sometimes rendered the rule(s) underlying aggression and cooperation in animals indistinct. Hereafter, whenever possible, we consider aggression and cooperation to be a continuous trait in group living animals, and solitary and group living (≥2) to be distinct traits in order to make the discussion clearer. We then attempt to discuss how aggression and coop...

Sexual Shape and Size Dimorphism in Carabid Beetles of the GenusCeroglossus: is Geometric Body Size Similar Between Sexes Due to Sex Ratio?

“…In the past few decades, a number of hypotheses have been proposed to explain sexual dimorphism in insects (Fairbairn, 1997;Wiklund and Forsberg, 1991;Walker and Rypstra, 2001;Esperk, 2007). The most solidly grounded hypothesis is the connection of sexual selection with natural selection, along with environmental variation, although male-male competition (Saito and Mori, 2005;Emlen, 2008), and the segregation of sexes due to limited resources (Saito & Mori, 2005) have produced notable selective differentia-tion.…”

Male–male aggression peaks at intermediate relatedness in a social spider mite

“…It can emerge when additionally local competition between males for mating opportunities is taken into account (Reinhold 2003;. Otherwise, a linear relation would be expected, as argued by Saito and Mori (2005). According to Saito (2000) and Saito and Mori (2005), nest defense by two males is far more effective than that by one male (Saito 1986b;Yano et al 2011).…”

“…Otherwise, a linear relation would be expected, as argued by Saito and Mori (2005). According to Saito (2000) and Saito and Mori (2005), nest defense by two males is far more effective than that by one male (Saito 1986b;Yano et al 2011). Thus, the killing of conspecific males within nests has two contrasting effects: it decreases fitness by exposing mating partners and offspring to the risk of predation, but it increases the fitness of an individual male by monopolizing females (Saito 1990a).…”

Counterattack success of a social spider mite against two predominant phytoseiid predator species

“…1), even though the value is still tentative. Therefore, these are important prerequisites to apply to the Saito and Takada (2009) model, which suggests that there is a condition under which male aggression (individual selection for getting mates) must compromise with male cooperation (kin selection for nest defense) depending upon the three parameters, r (relatedness), k (cost of aggression) and s (benefit of cooperation in counterattack) in S. miscanthi (Saito and Mori 2005;Saito 2010). …”