Does prior residency interact with loss? A study of male–male contests in the hermit crab Pagurus minutus

Abstract

Residency is an important predictor of success in contests with ownership asymmetries. Residency often can interact with a winning experience. However, given that some residents lose a contest even when showing an ownership advantage and that the process leading to loss often determines the loser's subsequent success, prior ownership might also interact with a loss. Here, we staged experimental contests between males of the hermit crab Pagurus minutus with a similar‐sized weapon (i.e., cheliped) to examine this possibility. Male–male contests in this species occur between a solitary intruder and an owner guarding a mature female. We evaluated (a) whether resource ownership and female value affect the contest outcome and (b) whether the probability of winning after losing differs depending on the initial role of the loser (i.e., owner or intruder) by using precopulatory guarding pairs of P. minutus collected from the field. In the first fighting trial, we found an ownership advantage and increasing owner success as the body size of his partner increased. Although some owners lost the fight, in contrast to our prediction, the frequency of losing in the second fighting trial did not differ between prior owners and prior intruders. Because losers from the first fighting trial of male–male contests have no female regardless of their initial role, this shared solitary status might be related to the lack of difference in success in the second fighting trial. Moreover, unlike in other animals, resident status might not always assure greater fighting ability in P. minutus males because guarding Pagurus males can avoid male–male contests by climbing up objects in the field. Losers in the first trial, therefore, may have been weaker contestants based on traits other than size, regardless of whether they were owners or intruders.

How feedback and feed‐forward mechanisms link determinants of social dominance

“…Feedback exists because individuals value a resource they ‘own’, such as a burrow or territory, more highly than an intruder does, meaning that owners should invest more highly in contests for the resource (Maynard Smith & Parker, 1976; Enquist & Leimar, 1987). Accordingly, residents, or owners, typically win the majority of contests when faced with an intruder (Nosil, 2002; Fuxjager et al ., 2009; Umbers, Osborne & Keogh, 2012; Yasuda et al ., 2020), and this winning propensity often increases with ownership time (Krebs, 1982; O'Connor et al ., 2015). Thus, effects of prior interactions on resource value can represent both positive and negative feedback loops.…”

“…Such studies therefore remove many of the additional factors that potentially influence contest outcomes in natural populations. Thus, while their existence is well established, the broader importance of winner-loser effects, especially in conjunction with other factors, to wild animal groups remains unclear (but see Fuxjager et al, 2009;Franz et al, 2015;Yasuda, Kaida & Koga, 2020).…”