MCELROY, E.J.*; REILLY, S.M.; Ohio University; Ohio University: Preliminary analyses of locomotor consquences of foraging mode in lizards
Foraging mode has been shown to have an immense impact on numerous aspects of lizard biology. However, few studies have addressed the impact of foraging mode on locomotor dynamics and limb morphology. This preliminary study focuses on the relationship between foraging mode, morphology, and locomotor dynamics among a phylogenetically broad sample of lizards. A racetrack with incorporated force plate was synchronized with high-speed video to quantify whole-body mechanics and gait patterns. Principle components analysis was utilized to explore patterns in limb segmental morphology. Foraging mode data was gleaned from the literature and analyzed using a trimodal, gap-coded interpretation: sit-and-wait (Percent time moving < 10%), medium (PTM ~ 15-40%), and wide foraging (PTM > 45%) mode. Patterns in whole-body mechanics, gait, and limb morphology were mapped onto a phylogeny coded with foraging mode. Sit-and-wait foraging (e.g. Iguania) was characterized by trotting gaits (limb phase (l.p.) ~ 50%), bouncing mechanics (phase shift (p.s.) ~ 0 � 45°), and intermediate segmental limb morphology. Shifts to medium and wide foraging among scleroglossans were characterized by the addition of vaulting mechanics (p.s. ~ 180 � 45° Scincidae, Gerrhosauridae, and Teiidae) and the retention of bouncing mechanics (all above groups). Gerrhosauridae and Teiidae shifted to a lateral sequence diagonal couplets gait (l.p. ~ 40%, duty factor (d.f.) ~ 30-60%) with longer hind feet (metatarsus and fourth toe). Scincidae shifted to higher duty factor trots (l.p. ~ 50%, d. f. ~ 50-80%) with reduced upper limb segments (femur/humerus, tibia/radius). These patterns are hypothesized to facilitate slower, more continuous locomotion characteristic of wider foragers while retaining the ability to sprint during predator escape.
