As an essential biomedical model organism, house mice have been studied intensely under laboratory conditions, yet they evolved to survive and reproduce in complex and dynamic environments. There has been recent interest in the study of "rewilded" mice reared in complex outdoor environments, particularly for understanding the brain and behavior. Yet little work has examined lab mouse behavior under free-living conditions. Here, we characterize the emergent spatial and social structure of replicated populations of C57BL/6J (C57) mice over 10 days in large outdoor field enclosures and compare them to populations of recently wild-derived outbred house mice under the same conditions. We observed shared aspects of space use and social structure across all trials but found that C57 societies differed from those emerging from outbred mice across multiple dimensions. Males of both genotypes rapidly established and then defended territories. Female C57 mice spent more time with other individuals and explored more space relative to all other groups. These behavioral differences resulted in C57 mice rapidly forming less stable, but more densely connected, social networks than outbred wild-derived mice. These data suggest that laboratory domestication has had larger effects on female mouse social organization than their male counterparts. Importantly, this work demonstrates that C57 mice recapitulate many, but not all, aspects of social structures generated by wild mice in outdoor conditions. Rewilding allows for tractable, replicable, and ecologically realistic approaches to studying mouse behavior and can facilitate the study of the biological basis of higher order social organization.

Previous studies have considered floral humidity to be an inadvertent consequence of nectar evaporation, which could be exploited as a cue by nectar-seeking pollinators. By contrast, our interdisciplinary study of a night-blooming flower, Datura wrightii, and its hawkmoth pollinator, Manduca sexta, reveals that floral relative humidity acts as a mutually beneficial signal in this system. The distinction between cue- and signal-based functions is illustrated by three experimental findings. First, floral humidity gradients in Datura are nearly ten-fold greater than those reported for other species, and result from active (stomatal conductance) rather than passive (nectar evaporation) processes. These humidity gradients are sustained in the face of wind and are reconstituted within seconds of moth visitation, implying substantial physiological costs to these desert plants. Second, the water balance costs in Datura are compensated through increased visitation by Manduca moths, with concomitant increases in pollen export. We show that moths are innately attracted to humid flowers, even when floral humidity and nectar rewards are experimentally decoupled. Moreover, moths can track minute changes in humidity via antennal hygrosensory sensilla but fail to do so when these sensilla are experimentally occluded. Third, their preference for humid flowers benefits hawkmoths by reducing the energetic costs of flower handling during nectar foraging. Taken together, these findings suggest that floral humidity may function as a signal mediating the final stages of floral choice by hawkmoths, complementing the attractive functions of visual and olfactory signals beyond the floral threshold in this nocturnal plant-pollinator system.

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Internal states shape responses to sensory stimuli. Mammalian female reproductive states are understudied considering they are one of the most regular state changes in the animal kingdom. Here we examine female house mouse preferences toward male odors across the reproductive states of estrus and late-stage pregnancy. In house mice, urine scent marks are salient social odors that convey information about the sex and identity of individuals by major urinary proteins (MUPs). Males secrete a sex-specific pheromonal protein called darcin (MUP20). Additionally, genetically diverse mice secrete unique combinations of MUPs used in individual recognition. Prior work has revealed that male odors are powerful social stimuli for female mice, yet we have a limited understanding of how the valence of such odors change across reproductive states. We discovered a valence shift among estrus and pregnant females toward novel male urine, in which estrus females exhibit preference and pregnant females show strong avoidance. This valence switch also occurs toward darcin alone, providing further support for darcin as a strong sexual signal. However, when presented with familiar male urine, the approach-avoidance response disappears, even when additional darcin is added. In contrast, when an existing identity protein (MUP11) is added to familiar male urine the approach-avoidance response is recovered. This indicates that darcin in the absence of other identity information denotes a novel male and that familiar identity information present in male urine is sufficient to modify responses to darcin. Our findings suggest that the sex and identity information encoded by MUPs are likely processed via distinct, and potentially opposing pathways, that modulate responses toward complex social odor blends. Furthermore, we identify a state-modulated shift in decision-making toward social odors and propose a neural circuit model for this flow of information. These data underscore the importance of physiological state and signal context for interpreting the meaning and importance of social odors.

Although visual and olfactory floral signals attract pollinators from a distance, at the flower’s threshold, pollinators can use floral humidity as an index cue for nectar presence. We evaluate the role of floral humidity in the Datura wrightii-Manduca sexta nocturnal pollination system. In addition to our finding that M. sexta shows strong innate attraction toward humid flowers, we identify the hygrosensing sensillum on their antennae, demonstrate its extreme sensitivity to minute changes in RH, and observe the elimination of moths’ behavioral preference towards humid flowers following experimental occlusion of the sensilla. Despite Manduca’s attraction toward humid flowers, we find that floral humidity is not a reliable cue for nectar presence in this system. While Datura floral headspace sustains an enormous humidity gradient, it is not a consequence of nectar evaporation, but an outcome of gas exchange through floral stomata and is decoupled from nectar presence. Using interdisciplinary tools, we demonstrate the function of floral humidity as an attractive signal, not a cue, in this pollination system, thus showcasing an underappreciated modality by which flowers may manipulate their visitors.

Vigilant animals detect and respond to threats in the environment, often changing posture and movement patterns. In social animals vigilance is modulated not only by predators but also by threatening conspecifics. Precisely how social interactions alter vigilance behavior over time is not well understood. We report persistent effects of a simulated social challenge on the vigilance behavior of wild northern paper wasp foundresses, Polistes fuscatus. During the founding phase of the colony cycle conspecific wasps may usurp nests from the resident foundress, representing a severe threat. Using postural tracking, we found that after simulated intrusions wasps displayed increased vigilance during the minutes after the threat was removed. Sustained vigilance elicited after social threat manifested as increased movement, greater bilateral wing extension, and reduced antennal separation. However, no postural changes were observed after a control stimulus presentation. By rapidly adjusting individual vigilance behavior after fending off a conspecific intruder, paper wasp foundresses invest in surveillance of potential social threats, even when such threats are no longer immediately present. The prolonged state of vigilance observed here is relevant to plasticity of recognition processes as a result of conspecific threats.

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Behaviors are among the most complex phenotypes, making the genetic dissection of behavioral differences extremely challenging. A careful dissection of ontogenetic differences in burrowing behavior between mouse species highlights the importance of integrative approaches to the study of behavioral evolution.