02215nas a2200241   4500008004100000245008200041210006900123260001600192520143800208653003801646653002701684653002501711653003201736653001501768100002601783700002301809700002401832700001501856700001801871700002301889700001801912856004301930       2018                        eng d00aAge-dependent variation in the terminal investment threshold in male crickets0 aAgedependent variation in the terminal investment threshold in m  cJan-02-20183 a<p>The terminal investment hypothesis proposes that decreased expectation of future reproduction (e.g., arising from a threat to survival) should precipitate increased investment in current reproduction. The level at which a cue of decreased survival is sufficient to trigger terminal investment (i.e., the terminal investment threshold) may vary according to other factors that influence expectation for future reproduction. We test whether the terminal investment threshold varies with age in male crickets, using heat-killed bacteria to simulate an immune-inducing infection. We measured calling effort (a behavior essential for mating) and hemolymph antimicrobial activity in young and old males across a gradient of increasing infection cue intensity. There was a significant interaction between the infection cue and age in their effect on calling effort, confirming the existence of a dynamic terminal investment threshold: young males reduced effort at all infection levels, whereas old males increased effort at the highest levels relative to na&iuml;ve individuals. A lack of a corresponding decrease in antibacterial activity suggests that altered reproductive effort is not traded against investment in this component of immunity. Collectively, these results support the existence of a dynamic terminal investment threshold, perhaps accounting for some of the conflicting evidence in support of terminal investment.</p>
10aAge-dependent reproductive effort10afecundity compensation10aGryllodes sigillatus10aresidual reproductive value10atrade-offs1 aDuffield, Kristin, R.1 aHampton, Kylie, J.1 aHouslay, Thomas, M.1 aHunt, John1 aRapkin, James1 aSakaluk, Scott, K.1 aSadd, Ben, M.  uhttp://doi.wiley.com/10.1111/evo.13443