Females prefer cooperative males even when cooperative behavior is unobserved: evidence from the mound-building mouse,Mus spicilegus

Abstract

10Theoretical and empirical studies in humans suggest that cooperative behaviors may act as 11 signals during mate choice. However, cooperation is not always observable by potential partners 12 before mate choice. To address whether cooperative phenotypes are preferred based on cues 13 different from cooperative behaviors per se, we designed an experimental paradigm using wild-14 born mound-building mice (Mus spicilegus), a species with biparental care. In this species, 15 females cannot observe male cooperative behaviors: mate choice occurs in the spring, whereas 16 mounds are cooperatively built in the fall. We first assessed the variation in mound building 17 investment and identified males exhibiting high and low amounts of cooperation. Second, we 18 presented these males to females during two-way choice tests. As offspring survival relies on 19 mound protection, we hypothesized that mound building could be a form of paternal care and 20 assessed whether cooperative males were more involved in offspring attendance using pup-21 retrieval experiments. Our results indicate that females were more attracted to highly 22 cooperative males over less cooperative, even when they did not observe them build. This 23 finding suggests that female mate choice is influenced either by cues of cooperativeness 24 different than cooperative behaviors or by preferences for traits associated with 25 cooperativeness. Moreover, male offspring attendance was negatively correlated with 26 cooperativeness, suggesting the potential existence of two alternative paternal strategies in 27 offspring care (mound building versus offspring attendance). Overall, our findings support the 28 not peer-reviewed) is the author/funder. All rights reserved. No reuse allowed without permission.The copyright holder for this preprint (which was . http://dx.doi.org/10.1101/197988 doi: bioRxiv preprint first posted online 2 existence of preference for cooperative phenotypes in a non-human species and suggest that 29 sexual selection might be involved in the evolution of cooperation. 30

Exploring the causes and consequences of cooperative behaviour in wild animal populations using a social network approach

“…Tognetti et al . (2017) found that more cooperative males are preferred regardless of whether or not they were previously observed by the females, indicating that a preference for more cooperative individuals is not necessarily indicative of indirect reciprocity. It is possible that cooperative propensity is correlated with another attractive, sexually selected trait.…”

“…It is important to consider the possibility that these seemingly more complex routes to cooperation can also be maintained in different, less cognitively demanding ways (Carter, 2014). For example, Tognetti et al (2017) suggest that cooperation may be maintained through sexual selection; if the 'cooperative phenotype' is associated with other sexually selected traits then cooperation can evolve and be maintained through its association with them. Steppe mice (Mus spicilegus) invest in cooperative mound building, which can be understood as a form of parental care (Tognetti et al, 2017).…”

“…For example, Tognetti et al (2017) suggest that cooperation may be maintained through sexual selection; if the 'cooperative phenotype' is associated with other sexually selected traits then cooperation can evolve and be maintained through its association with them. Steppe mice (Mus spicilegus) invest in cooperative mound building, which can be understood as a form of parental care (Tognetti et al, 2017). After classifying males as more or less cooperative based on their mound building investment in the autumn, Tognetti et al (2017) exposed females to one highcooperation male and one low-cooperation male in pairs during the breeding season.…”

“…Steppe mice (Mus spicilegus) invest in cooperative mound building, which can be understood as a form of parental care (Tognetti et al, 2017). After classifying males as more or less cooperative based on their mound building investment in the autumn, Tognetti et al (2017) exposed females to one highcooperation male and one low-cooperation male in pairs during the breeding season. Choosing a mate that makes higher investments in mound building can lead to having a larger mound which can increase the probability of offspring survival.…”