Laboratory-reared and field-collected predators respond differently to same experimental treatments

Abstract

Laboratory studies of animal behavior can use animals with different developmental histories, including those that have spent most of their lives in the field or those raised in the laboratory. Both types of animals are assumed to respond similarly to experimental treatments. The goal of this study was to test if this assumption is true, if field-collected and lab-reared animals respond similarly to experimental treatments. In the first experiments, we test how diet (high lipid or protein) affected mating behaviors of male jumping spiders, Phidippus audax. Male spiders had opposite responses to diet based on their rearing condition in both scramble competition and male-male interaction trials. Field-collected spiders fed with high-protein diets and lab-reared spiders fed with high-lipid diets found mates quicker and were more aggressive than their counter parts fed with different diets. Field-collected spiders were also more active in open arenas and courted females more actively than lab-reared spiders. In a second experiment, we tested spiders for preference of flower color, and found that both lab-reared and field-collected spiders selected flowers with color over white flowers. However, field-collected spiders prefer red flowers with UV fluorescence, while lab-reared spiders seem to prefer red without UV. These results suggest that lab-reared and field-collected animals can respond differently to the same experimental treatments. Further work is needed to test if this happens in other animals, and which types of individuals (lab-reared or field collect) best reflect the responses of animals in nature. Laboratory studies are commonly used to study animal behavior. Animals used in these studies can be either raised in the laboratory or collected from the field just prior to the study. While lab-reared and field-collected animals can differ sometimes in their behavior (e.g., more or less active in response to a treatment), they are both assumed to respond in qualitatively the same manner. However, this does not appear to be the case in our study of a common species of jumping spider, Phidippus audax. Lab-reared and field-collected animals responded in opposite directions to identical treatment conditions. These results suggest that the developmental histories of animals can fundamentally affect how they respond to experimental treatments in the laboratory and, hence, the conclusions drawn from such studies.