Developmental stress in birds: phenotypic and fitness

Abstract

The environment animals experience during development can have important effects on phenotype, performance, and fitness across multiple life-history stages. Environmental cues experienced during development can provide information to animals about the environment they will soon inhabit and promote phenotypic changes which affect fitness. Increasing evidence suggests that physiological stress may be one such cue that conveys environmental information to developing animals. Here, I explore the short- and long-term consequences of developmental stress in captive and free-living birds. In chapter one, I explore the effects of developmental stress on body size and physiological stress responses across life-history stages in zebra finches (Taeniopygia guttata). I found that developmental stress increases stress response and decreases body size in juvenile zebra finches. In chapter two, I examine the effects of developmental stress on learning in zebra finches. Developmental stress has well-known suppressive effects on song learning in passerines. I examine whether this is generalizable for other types of learning, specifically learning that relates to foraging. I found that adult zebra finches exposed to developmental stress learned a novel foraging task faster compared to control siblings. In chapter three, I investigated the effects of developmental stress on male reproductive success in zebra finches. I found that developmentally stressed males invested more in parental care and reared nestlings in better condition compared to control males. Developmentally stressed males also sired more offspring and were less likely raise non-genetic nestlings compared to control males. In chapters four and five, I explore the causes and consequences of stressors in a free-living model species, the white-crowned sparrow (Zonotrichia leucophryus oriantha). I examine the effects of an anthropogenic stressor (a high traffic road) on nestling stress responses, growth, and survival. I found that proximity to a road increased both nest failure due to predation and nestling stress responses. Cumulatively, these studies expand our understanding of the phenotypic and fitness consequences of developmental stress. In contrast to most studies, I find several beneficial outcomes in response to developmental stress. Hence, early life stress appears to shape phenotype and performance in some ways that are beneficial