Biology subjects

Rosher, C.

Publications and source records attributed to Rosher, C..

4 recordsLinked to original sources

bioRxiv2025

The TRP-channel painless mediates substrate stiffness sensing in the legs during Drosophila oviposition

The distinct textural properties of fruits in varying stages of ripening present unique ecological opportunities for several species of fruit flies, resulting, over evolutionary times, in specialized egg-laying behaviors. In this study we identified a TrpA channel-dependent mechanosensory pathway in the legs, through the gene painless, that modulates the discernment of softer patches for oviposition in gravid D. melanogaster females. We report that the stiffness-sensing role of tarsi is mediated through external sensory organs housed, namely ventral mechanosensory bristles and subsets of campaniform sensilla present primarily at the joints between tarsomeres. Our findings provide new evidence that campaniform sensilla function as indirect stiffness sensors of oviposition substrates, owing to their placement at joints that experience maximal cuticular distortion. We show that Painless is expressed in mechanosensory neurons innervating peripheral organs where it likely participates in the transduction of stiffness-evoked stimuli. Furthermore, we observed that overexpression of painless in both campaniform sensilla and mechanosensory bristles partially rescues preference for the softer substrates in painless mutants, indicating that painless activity in these organs is necessary to mediate the preference. We propose that different interactions with a soft vs. a hard substrate (compression of the cuticle, distribution of contacts) results in differential mechanotransduction in painless-expressing neurons, determining oviposition preferences.

neuroscience↗

bioRxiv2024

Covert muscle activity reveals dynamic freezing states and prepares the animal for action

When an animal detects a threat it must make a split-second choice between fight, flight or freezing (1-3). During freezing, skeletal muscles sustain tension to maintain rigid, sometimes atypical postures, for many minutes at a time (4). Meanwhile the animal must dynamically assess its surroundings to plan future actions and ready its body for movement. The interplay between the neural and somatic systems during freezing remains poorly understood. Here we show that freezing Drosophila melanogaster display a striking novel pattern of leg muscle activation unique to immobility, a rhythmic pulsing in the distal tibia. The muscle, which we show to be a previously undescribed leg accessory heart, displays multiple activity modes and ramps up to movement onset, implying a preparation for movement. The frequency of pulsing is dynamically modulated as the fly integrates external threat or safety cues, and artificially increasing pulse frequency leads to freezing breaks, indicating a causal role in the decision to move. Through the identification of a new Drosophila cardiac organ, this study provides a window into the multiple states which can underlie freezing behaviour, and the physiological changes which the body undergoes to ready the animal to move.

neuroscience↗

bioRxiv2023

A single genetic locus lengthens deer mouse burrows via motor pattern evolution

The question of how evolution builds complex behaviors has long fascinated biologists. To address this question from a genetic perspective, we capitalize on variation in innate burrowing behavior between two sister species of Peromyscus mice: P. maniculatus that construct short, simple burrows and P. polionotus that uniquely construct long, elaborate burrows. We identify three regions of the genome associated with differences in burrow length and then narrow in on one large-effect 12-Mb locus on chromosome 4. By introgressing the P. polionotus allele into a P. maniculatus background, we demonstrate this locus, on its own, increases burrow length by 20%. Next, by recording mice digging in a transparent tube, we find this locus has specific effects on burrowing behavior. This locus does not affect time spent digging or latency to dig, but rather affects usage of only two of the primary digging behaviors that differ between the focal species: forelimb digging, which loosens substrate, and hindlimb kicking, which powerfully ejects substrate. This locus has an especially large effect on hindkicking, explaining 56% and 22% of interspecific differences in latency and proportion of hindkicks, respectively. Together, these data provide genetic support for the hierarchical organization of complex behaviors, offering evolution the opportunity to tinker with specific behavioral components.

evolutionary biology↗

bioRxiv2018

Reproductive skew affects social information use

Individuals vary in their propensity to use social learning, the engine of cultural evolution, to acquire information about their environment. The causes of those differences, however, remain largely unclear. Individuals that experience high reproductive skew are expected to favour high-risk strategies, whereas those that experience low reproductive skew are expected to favour risk-averse strategies. Using an agent-based model, we tested the hypothesis that differences in energetic requirements for reproduction affect the value of social information. We found that social learning is associated with lower variance in yield and is more likely to evolve in risk-averse low-skew populations than in high-skew populations. Reproductive skew may also result in sex differences in social information use, as females tend to be more risk averse than males. To explore how risk may affect sex differences in learning strategies, we simulated learning in sexually reproducing populations. Where both sexes share the same environment they adopt more extreme learning strategies, approaching pure individual or social learning. These results provide insight into the conditions that promote individual and species level variation in social learning and so may affect cultural evolution.

evolutionary biology↗