Birth and the pathway to adulthood: integration across development, environment, and evolution

Birth, and the period shortly thereafter, is a perilous time for any organism. Following parturition or hatching, individuals face many challenges, including environmental stressors (e.g., temperature or humidity), competition, and/or predation, all of which can impact selection (Lindstrom 1999; Metcalfe and Monaghan 2001; Gluckman and Hanson 2004). Furthermore, major anatomical, behavioral, and physiologic changes occur throughout the ontogenetic period. As such, the conditions an organism experiences throughout the ontogenetic period have implications for their survival, success, and ultimately, their fitness (Lindstrom 1999; Lee et al. 2003; Nord and Nilsson 2016; Nord and Giroud 2020). An understanding of developmental strategy, neonatal condition, and environmental challenges, as well as the physiology of newly born/hatched individuals experiencing those conditions, is critical for evaluating how adult organisms function and survive. However, these topics are often studied in isolation, both across different systems, and at a single point in time