Adversity early in life can have long-lasting impacts on health outcomes for humans, even if their circumstances improve later on. Scientists have developed a cumulative adversity index (CAI) to quantify measures of hardship such as poverty and stress, which has helped identify ways to improve people’s lives. While wild animals also experience adversity early in life, the effects on their survival and longevity are unknown. Few animal populations have been studied for long enough to develop a CAI, but UCLA biologists are changing that by creating the first CAI for yellow-bellied marmots using 62 years of data collection.
Through their research, scientists identified several stressors that significantly impact marmot survival and longevity, including late start of the growing season, maternal loss, and maternal stress. Surprisingly, some stressors such as summer drought and predation did not have as large of an impact as expected. The study also found that late weaning and poor maternal mass decreased survival odds. By analyzing data on female marmots, researchers were able to create computer models that quantified different levels of adversity and their impact on pup survival, revealing that moderate and acute adversity reduced the odds of survival by 30% and 40%, respectively.
The research showed that adverse experiences early in life accumulate and have long-term effects on marmot lifespan, with increased adversity leading to decreased adult lifespan. This suggests that positive experiences later in life do not fully counteract the negative impacts of early adversity. The results supported the hypothesis that a CAI could be a useful tool for evaluating the survival impact of multiple early life stressors in marmots. By understanding the cumulative effects of different stressors, conservationists can better target interventions to support marmot populations.
The study highlighted the importance of considering the cumulative impact of multiple stressors on wildlife populations. By using a CAI, researchers can identify the most influential stressors and develop targeted conservation strategies. In the case of yellow-bellied marmots, conservation efforts may focus on reducing maternal mortality and improving maternal health, rather than targeting factors such as predation or summer drought, which were found to be less significant than expected. The research emphasized the need for a comprehensive approach to biodiversity management, considering the combined effects of various stressors on animal populations.