Meeting Abstract
During predator-prey encounters, maximal performance capacities often determine the outcome of whether the prey or predator survives. Performance is a direct result of an individual’s morphology, so morphology is indirectly a predictor of individual fitness. Many studies have looked at individual morphology and performance capacities, but they have historically been conducted in a laboratory setting on standard substrates. Reality is more complex than a laboratory because there are many substrates available in nature that differ from a single, standard substrate. Performance may vary among substrates and different morphological traits may be favored on each. Thus, natural selection acts on different traits across substrates, and fitness is determined by performance on and among substrates as well as substrate choice. We explored the relationship between morphology and performance by examining maximal sprint performance and sensitivity of wild-caught six-lined racerunner (Aspidoscelis sexlineata) lizards on four simulated substrates that mimic natural substrates: sandpaper (rock), sand, pebbles, and grass. We also identified morphological predictors of performance on each substrate. We measured substrate use in these lizards relative to available habitats. Only performance on grass was found to be suboptimal, but all sensitivity measures were correlated with each other. Performance on different substrates was predicted by different morphological traits. Performance trade-offs were found between grass and sandpaper, grass and pebbles, and between sand and pebbles after correcting for overall individual quality. Lizards tended to use substrates that optimized performance.
