Behaviour 2019
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A Framework to Evaluate the Fitness Consequences of Multiple Early-Life Stressors in Wild Populations  
Xochitl Ortiz-Ross, Daniel T. Blumstein. University of California, Los Angeles, CA, United States

Species worldwide are facing adverse conditions on multiple fronts (e.g., habitat loss, extreme weather, pollution, etc.), yet few studies have investigated the cumulative effect of multiple stressors on the fitness of wild populations. While organisms can sometimes cope with individual stressors, adjusting to multiple stressors likely requires trade-offs that can result in impaired fitness. This is especially true of stressors experienced early in life, which can disproportionately impact fitness. To address this problem, human studies have adopted a cumulative risk model that effectively identifies individuals at higher health and mortality risks based on the sum of their early-life risk exposure. However, such a model has rarely been applied in wild animal populations. To encourage greater research in this area and investigate the suitability of cumulative risk models in assessing the fitness of wild populations, I will briefly review how early life adversity has been modeled in human health studies and outline a general framework on how to build, use, and evaluate a cumulative adversity index for natural populations.