Bioenergetics of behavioural strategies in desert income and capital breeders

Income and capital breeders adopt distinct reproductive strategies based on available resources. Income breeders rely on resources currently accessible in the environment, while capital breeders rely on stored resources. Bioenergetic performance and trade-off models predict, respectively, that high maintenance cost signals either high energy turnover, supporting behaviours with high energy demands, or allocation and compensation between costly behaviours and physiological maintenance. We studied bioenergetics and personality traits of two sympatric rodent species representing distinct life-history strategies in a harsh desert environment. We found that the putative income breeder, roaming forager African hammada jerboa (Jaculushirtipes), may operate under performance bioenergetic mechanisms, were high maintenance costs co-express with repeatable exploratory behaviour. In contrast, a putative capital breeder, sedentary hoarder Shaw's jird (Meriones shawi), operates under allocation bioenergetic mechanisms, where maintenance cost negatively correlates with exploratory behaviour. We propose that integrating bioenergetics into the income-capital breeder concept provides proximate and adaptive predictions about how diversity of reproductive strategies is maintained, especially in resource-limited environments.