Chapter 1 examines the evolution of olfactory vomeronasal receptors (V1Rs) across mouse species within the Mus genus. We find evidence for distinct evolutionary trajectories across receptor clades and species-specific gene expansions. Chapter 2 utilizes thermal imaging to investigate scent mark signaling in male house mice toward variable social environments. Fight outcome and initial signal investment have profound and interactive effects on marking effort and the temporal dynamics of scent marking. Chapter 3 inspects the role of initial signaling effort in male house mice on contest dynamics. We demonstrate clear social costs to under-signaling, as low-marking competitive males engage in higher intensity fights that take longer to resolve. Chapter 4 explores how reproductive state shapes responses to social signals. We find that estrus and pregnant females exhibit a striking valence switch in preference toward novel male odors. We discover a state-modulated shift in decision-making and evidence for distinct processing pathways for sex and identity information.