Automated tracking reveals the social network of beach mice and their burrows

Abstract

Evolutionary biologists have long sought to understand the selective pressures driving phenotypic evolution. While most experimental data come from the study of morphological evolution, we know much less about the ultimate drivers of behavioral variation. Among the most striking examples of behavioral evolution are the long, complex burrows constructed by oldfield mice ( Peromyscus polionotus ssp.). Yet how these mice use burrows in the wild, and whether burrow length may affect fitness, remains unknown. A major barrier to studying behavior in the wild has been the lack of technologies to continuously monitor — in this case, nocturnal and underground — behavior. Here, we designed and implemented a novel radio frequency identification (RFID) system to track patterns of burrow use in a natural population of beach mice. We combine RFID monitoring with burrow measurements, genetic data, and social network analysis to uncover how these monogamous mice use burrows under fully natural ecological and social conditions. We first found that long burrows provide a more stable thermal environment and have higher juvenile activity than short burrows, underscoring the likely importance of long burrows for rearing young. We also find that adult mice consistently use multiple burrows throughout their home range and tend to use the same burrows at the same time as their genetic relatives, suggesting that inclusive fitness benefits may accrue for individuals that construct and maintain multiple burrows. Our study highlights how new automated tracking approaches can provide novel insights into animal behavior in the wild.

cis-Regulatory changes in locomotor genes are associated with the evolution of burrowing behavior

“…P. maniculatus dig short burrows (<10 cm), consisting of an entrance tunnel and a nest chamber, while P. polionotus construct longer (>35 cm) burrows that, in addition to an entrance tunnel and nest chamber, include an upward sloping ''escape tunnel'' (Figure 1A) (Dawson et al, 1988;Weber and Hoekstra, 2009). One explanation for this behavioral difference is that long burrows buffer against environmental fluctuations in the open habitats of P. polionotus (Bedford et al, 2021). Morphological comparisons between these two species have not found evidence for digging-related specializations (e.g., forepaw enlargement as seen in moles), suggesting that burrow differences are largely driven by behavioral mechanisms (Hu and Hoekstra, 2017).…”

Interspecific variation in cooperative burrowing behavior byPeromyscusmice

“…One important unanswered question is whether the longer burrows dug by opposite-sex pairs confer fitness benefits to the pair and/or their offspring. For example, a longer burrow may provide additional protection from predators or buffer against temperature and humidity fluctuations, which are particularly harmful to pups (Berry and Bronson 1992;Bedford et al 2021). Thus, reproductive pairs may engage in more simultaneous digging to efficiently construct longer burrows, which may, in turn, increase the odds of survival for the pair and/or their pups.…”

Two pup vocalization types are genetically and functionally separable in deer mice

“…We established colonies of P. m. bairdii, P. m. gambelli, P. p. subgriseus and P. leucopus from animals originally obtained from the Peromyscus Stock Center at the University of South Carolina. We established several colonies from wild-caught animals: P. m. nubiterrae (Kingsley et al, 2017), P. p. leucocephalus (Bedford et al, 2021), P. gossypinus (Delaney and Hoekstra, 2018), and P. m. rubidus (Hager et al, 2022). We housed all animals in barrier, specific-pathogen-free conditions with 16 h light: 8 h dark at 22˚ C in individually ventilated cages 18.6 cm x 29.8 cm x 12.8 cm height; Allentown, New Jersey) with quarter-inch Bed-ocob bedding (The Andersons, Maumee, Ohio).…”