Effects of Body Size and Slope on Acceleration of a Lizard ( Stellio Stellio )

Abstract

The agamid lizard Stellio ( = Agama) stellio L. accelerated quickly on a level track. Lizards reached 95 % of maximum speed in an average of only 0·31 m and 0·19s. Large lizards had higher initial accelerations (∼M1/3) and accelerated over longer distances and times than did small lizards. As a result, larger lizards achieved higher maximum speeds. Lizards of a given size that accelerated quickly also achieved high maximum speeds. Acceleration was also measured on slopes ranging from −15° to +60°. Steep inclines did not differentially reduce the initial acceleration of large versus small lizards, a result which contrasts with a previous demonstration that such inclines significantly reduce the maximum speed of only large lizards. Simulations of simple predatory-prey chases suggest that large lizards will be more successful if they attack distant prey on level or downhill slopes and that small lizards will be more likely to escape larger quadrupedal predators by fleeing uphill, unless the predators are near.