Drivers of in vivo bite performance in wild brown mouse lemurs and a comparison with the grey mouse lemur. (22nd February 2018) - Zablocki Thomas, P. B.
Abstract: Physical performance is crucial for animal survival and fitness. In this context, greater bite forces can provide advantages and may allow an individual to gain access to reproductive partners and/or different food resources. Here, we explored the determinants of bite force in a wild population of the brown mouse lemur ( Microcebus rufu s). Our objectives were to elucidate (1) if sex, head width, heart rate (as an indicator of overall physical fitness) and body condition drive variation in bite force in this population of wild mouse lemurs; and (2) the relative importance of the ecological niche in determining bite force by comparing results from this wild population with previously published results on bite force, body mass and head width from a laboratory colony of the grey mouse lemur ( Microcebus murinus ). We captured 32 wild brown mouse lemurs at night in the Ranomafana National Park in Madagascar during the beginning of the rainy season from 1st to 31st October 2016. We measured bite force, heart rate, body mass and head width of all individuals, and assigned sex and body condition (estimated as the unstandardized residual of a regression of body mass against head size). Although maximum bite force was positively correlated with body mass, it was not correlated with body condition. Residual bite force was highly correlated with residual head width and heart rate. The mean bite force of wild brown mouse lemurs was much lower than that of grey mouse lemurs in captivity, but showed similar relationships to head dimension and body mass. Even when corrected by body condition, grey mouse lemurs bit significantly harder than brown mouse lemurs. The difference in bite force between species could be explained by differences in head size and niche divergence with brown mouse lemurs eating mostly soft fruits and grey mouse lemurs eating more hard insects. Abstract : Greater bite forces can provide advantages and may allow an individual to gain access to reproductive partners and/or different food resources. Here we explored the determinants of bite force in a wild population of the brown mouse lemur ( Microcebus rufus ). We found that, whereas maximum bite force was positively correlated with body mass, it was not correlated with body condition, and residual bite force was highly correlated with residual head width and heart rate. The mean bite force of wild brown mouse lemurs was much lower than that of grey mouse lemurs in captivity, but showed similar relationships to head dimension and body mass. The difference in bite force between species could be explained by differences in head size and niche divergence with brown mouse lemurs eating mostly soft fruits and grey mouse lemurs eating more hard insects.