Sexual selection and senescence: do seed beetle males (Acanthoscelides obtectus, Bruchidae, Coleoptera) shape the longevity of their mates?

Abstract

Although the reasons why organisms age and die are generally well understood, it has recently been suggested that an optimal life span has evolved not only as the result of trade‐offs between reproductive performances early and late in life, but also that a balance between the costs and benefits of the number of mating has also played an important role in the evolution of ageing in both sexes. By using four seed beetle (Acanthoscelides obtectus) lines selected for different life history traits, but which have also inadvertently created monoandrous and polyandrous conditions, we showed that males evolved to affect the mortality patterns of females in a way consistent to the postmating sexual selection generated by sexually antagonistic co‐evolution theory. Monoandrous males, irrespectively of body weight and other life history traits specific to their lines, evolved to increase the longevity of control females kept under starvation and suppressed fecundity, compared with males that originated in the lines with effectively polyandrous conditions. When females were allowed to lay eggs, the effects of males from different lines and mating type history on the senescence of females were substantially weaker. We found that males in the line that was evolved to decelerate senescence and polyandrous conditions stimulate the earlier onset of females’ oviposition, relative to males stemmed from the line with accelerated senescence and monoandrous conditions. This fact may explain the absence of difference in the mean longevities between the control females mated to these males and highlight the importance of sexual selection in the evolution of ageing.

Age and sex‐specific mortality of wild and captive populations of a monogamous pair‐bonded primate (Aotus azarae)

“…In primates there is a documented role for an individual’s social bonds to influence their own and their offspring’s longevity [Nakamura et al, 2014; Silk et al, 2003; Silk et al, 2009; Silk et al, 2010]. Furthermore, emerging evidence across diverse taxa indicates an influence of partners within mating dyads on each other’s longevity [Monaghan et al, 2011; Šešlija et al, 2008]. Examining how each owl monkey pairmate influences the other’s age-specific mortality would be an interesting direction of research.…”

Sex Differences, Sexual Selection, and Ageing: An Experimental Evolution Approach

“…These results could reflect increased sexual conflict in long‐lived lines, and males could therefore be caught in an evolutionary dilemma between the necessities of winning in sperm competition versus prolonging their mates' life span. Recently, Seslija et al (2008, 2009) provided further discussion of the potential role of inadvertent manipulation of MS under different LH schedules for trait evolution in A. obtectus . The only way to avoid such problems and to directly test for the role of sexual selection in the evolution of age‐specific traits is to experimentally impose different LH schedules while simultaneously manipulating the opportunity for sexual selection (Bonduriansky et al 2008).…”

The effects of selection for early and late reproduction on metabolite pools in Acanthoscelides obtectus Say

“…Possibly, delayed reproduction in the O line maximized energy stores and supported the long life span of both females and males. Taking into account that reproduction is more costly to females than males, and that a polyandrous mating system imposes additional selection pressure on the O females (the presence of toxic substances in male ejaculate, increased mating frequency and re‐mating rate, Šešlija et al ., 2008, 2009a), it is likely that they also invest resources in other functions such as increased immunity and stress and toxicity resistance. At the same time, the O line individuals also have the most highly expressed sexual dimorphism for hydrophobic proteins, which had higher content in females.…”

“…Previous studies on Acanthoscelides obtectus have shown that selection for early and late reproduction led to correlated changes in many fitness and behavioral traits (Tucić et al ., 1996; 2004; Šešlija et al ; 2008, 2009a, 2009b; Stojković et al ., 2010). Selection for late reproduction not only increased mean life expectancy but also slowed down the ageing rate, suggesting the involvement of regulatory genes in the evolution of senescence of this species.…”