Age‐dependent male mating tactics in a spider mite—A life‐history perspective

Abstract

Males often fight with rival males for access to females. However, some males display nonfighting tactics such as sneaking, satellite behavior, or female mimicking. When these mating tactics comprise a conditional strategy, they are often thought to be explained by resource holding potential (RHP), that is, nonfighting tactics are displayed by less competitive males who are more likely to lose a fight. The alternative mating tactics, however, can also be explained by life‐history theory, which predicts that young males avoid fighting, regardless of their RHP, if it pays off to wait for future reproduction. Here, we test whether the sneaking tactic displayed by young males of the two‐spotted spider mite can be explained by life‐history theory. We tested whether young sneaker males survive longer than young fighter males after a bout of mild or strong competition with old fighter males. We also investigated whether old males have a more protective outer skin—a possible proxy for RHP—by measuring cuticle hardness and elasticity using nanoindentation. We found that young sneaker males survived longer than young fighter males after mild male competition. This difference was not found after strong male competition, which suggests that induction of sneaking tactic is affected by male density. Hardness and elasticity of the skin did not vary with male age. Given that earlier work could also not detect morphometric differences between fighter and sneaker males, we conclude that there is no apparent increase in RHP with age in the mite and age‐dependent male mating tactics in the mite can be explained only by life‐history theory. Because it is likely that fighting incurs a survival cost, age‐dependent alternative mating tactics may be explained by life‐history theory in many species when reproduction of old males is a significant factor in fitness.

Life history of aggression in Anastatus disparis (Hymenoptera: Eupelmidae) with extreme male–male combat

“…Fighting typically has lifetime consequences (Kemp, 2006; Sato et al ., 2016; Baxter and Dukas, 2017), and the life history of aggression with a dangerous fighting pattern was studied in A. disparis . Fighting in A. disparis is typically dangerous, resulting in severe injury or death (Liu et al ., 2017a; Liu and Hao, 2019).…”

Parental effects of male alternative reproductive tactics (ARTs) on ARTs of haploid sons

“…The signal of the ART of preceding guards may have come from cues left by the guards on the T‐female, or T‐females changed their smell in dependence of the guard, or some T‐females attracted more likely sneakers and others attracted more likely fighters. Dependency of adoption of a given ART on male age and density (Sato et al, ,) renders the explanation of ART‐specific cues left on T‐females more likely than the two other explanations. Males leaving chemical marks on their mates have been observed in various animals such as butterflies (Estrada et al, ) and fruit flies (Laturney & Billeter, ).…”

“…ART expression by males is conditionally dichotomous and reversible, with fighting and sneaking phenotypes, and evident in male–male combat and pre‐copulatory guarding behaviour (Sato, Sabelis, Egas, & Faraji, ). Fighters and sneakers differ in behaviour but not in body size and morphology (Sato, Rühr, Schmitz, Egas, & Blanke, ; Sato et al, ). Mate finding occurs by males actively searching for females.…”

“…Sneakers may also secure the guarding position when competing males engage in fights. Across conditions, more than 75% of males are fighters (Sato et al, ; Sato, Sabelis, & Egas, ). However, expression and proportional occurrence of ARTs depend on male density and age: intermediate male densities (4 to 7 males per T‐female) and young age disproportionally promote the frequency of the sneaking phenotype (up to 25%), whereas high densities and advanced age disproportionally promote the frequency of the fighting phenotype (Sato et al, , ).…”

Spider mite mothers adjust reproduction and sons' alternative reproductive tactics to immigrating alien conspecifics

“…Fighter phenotypes fight with other males to gain access to, and monopolize, T-females and challenge guarding fighter males to obtain the guarding position. Sneaker phenotypes do not fight with other males and are cryptic to, and thus not fought by, other males [19,20,23]. Guarding is highly important for fertilization success since copulation takes place immediately upon the emergence of mature females.…”