Plenary Talks

The house mouse is a highly tractable model species for experimental studies in behavioural ecology. In this talk, I will present results of our recent work using house mice (Mus musculus domesticus) as a model to explore the evolutionary basis of sex differences in competitive and parental behaviours. Key sex differences in the behaviour of sexually reproducing animals are rooted in anisogamy and amplified by sexual selection. This can explain why females often care for offspring and males compete for mates, but doesn't preclude females from competing aggressively for resources, or males from showing parental care. A key question is therefore whether intrasexual competition (for resources by females and mates by males) limits the ability to invest in parental care. We have utilised natural variation in the behaviour of wild-derived house mice to address this question, combining experimental manipulation of social contexts with genome-wide comparisons of gene expression, to explore potential constraints on competitive behaviour among females and parental care among males.

Populations that inhabit islands often evolve unusual body sizes. Small-bodied vertebrates tend to increase in size on islands, whereas large-bodied vertebrates tend to shrink, a pattern known as the island rule. Although the ecological drivers of the island rule have attracted the attention of biologists, the genetic basis of this evolutionary phenomenon is rarely investigated. House mice that recently colonized remote Gough Island have nearly doubled in size compared to their mainland counterparts. In this talk, I will share discoveries from our research treating Gough Island mice as a model system for understanding the island rule, including the phenotypic and genetic determinants of accelerated growth. I will also characterize the genetics of exploratory behavior in Gough Island mice, which show signs of reduced anxiety compared to their mainland relatives. Finally, I will discuss ways in which genome-wide patterns of DNA sequence variation both illuminate and complicate inferences about the evolution of extreme phenotypes on islands.

House mice harbor diverse communities of microorganisms, the densest of which reside in the gastrointestinal tract. This gut microbiota can affect house-mouse traits, motivating the study of microbiota transmission, evolution, and function in wild and laboratory house-mouse populations. In this talk, I trace the evolutionary history of the house mouse gut microbiota from the wild to the lab and explore implications of microbiota variation for house mouse development. Comparative studies have revealed that dozens of gut microbial symbionts have diversified in parallel with house mice and other rodent species over the past ~35 million years. Some of these ancestral symbiont lineages have been retained within and show signatures of adaptation to laboratory lines of house mice, but most have been lost. The retention and vertical transmission of gut symbionts in laboratory lines has the potential to confound studies of mouse genetics, whereas the loss of gut symbionts has implications for the utility of laboratory mice as a mammalian model. Experiments in germ-free and ‘rewilded’ mouse populations can overcome these issues. Using data from such experiments, I present evidence that the host-species specific gut symbionts of house mice are critical for the development of immune and metabolic house-mouse phenotypes.