The effect of ambient temperature on locomotor activity patterns in reproductive and non-reproductive female Damaraland mole-rats

Abstract

The subterranean niche is a specialized environment that presents its inhabitants with a unique set of microclimatic conditions. African mole-rats are strictly subterranean and exhibit a continuum of sociality ranging from solitary to highly social. Colonies of the Damaraland mole-rat comprise of a dominant breeding or reproductive female and one or two male consorts and a number of subordinate and non-reproductive individuals of both sexes. In this study we investigated the locomotor activity patterns of reproductive and non-reproductive female Damaraland mole-rats with the intention to investigate daily timing of activity and activity levels with changes in ambient temperature, and also whether activity would differ between the reproductive castes at different ambient temperatures. The Damaraland mole-rats displayed predominantly nocturnal activity at all three temperatures, and the levels of activity were different for all three temperatures tested. Molerats exhibited the lowest levels of activity at 30ºC, they are most active at 25ºC while they display intermediate levels of activity at 20ºC. Despite exhibiting the majority of their activity during the night, non-reproductive females display significantly more day time activity compared to the reproductive females at all three temperatures. Nocturnal activity is comparable between reproductive and non-reproductive animals at 20 ºC and 25 ºC, but not at 30 ºC. Daily locomotor activity rhythms of the Damaraland mole-rats appear to be relatively flexible and respond to comparatively small changes in ambient temperatures. Differences in daily activity between reproductive and non-reproductive animals may emphasize the existence of physiological and morphological castes in the Damaraland mole-rat.