Meeting Abstract

43.6  Tuesday, Jan. 5  Loading effects on jumping and running in green anole lizards (Anolis carolinensis) KUO, CY*; IRSCHICK, DJ; Univ. of Massachusetts Amherst; Univ. of Massachusetts Amherst chiyun@bio.umass.edu

Animals in nature commonly encounter the problem of large loads that they must carry, such as when they are pregnant, have consumed a large meal, etc. By studying how animals cope with large loads, one can also examine how the musculoskeletal system drives locomotion, particularly in terms of how much mechanical power muscles can produce. There has been extensive research to quantify such effects on terrestrial horizontal locomotion. However, the effects of increased loads for two modes of locomotion that require large amounts of power, namely vertical running and jumping, have been less well-studied. Green anoles are a good study system for this line of inquiry because of their arboreal lifestyle, and their propensity to run uphill and jump from branch to branch. In addition, males have large heads relative to females, which can be regarded as a load that might impose a constraint on vertical running and jumping. Female anoles, on the other hand, have to carry eggs, which also represents a load. In this study, we tested three hypotheses concerning the influence of weight loading on performances and kinematics of two modes of locomotion . First, are larger anoles affected to a greater or lesser extent by proportional loads (expressed as a similar percentage of body weight) compared to small anoles? Second, does loading on more distal body parts have more of an influence on locomotor performance compared to loading on the center of the body?. Third, are male lizards affected to a greater extent by loading on the body compared to female lizards, who must normally cope with large loads in nature due to pregnancy. Our work sheds light on both the dynamics of jumping and running, and specifically, how animals cope with extra loads both behaviorally and mechanically.