Periodic Reporting for period 1 - AGEISM (Lifelong health, markers of ageing and senescence in a long-lived mammal.)
Reporting period: 2016-01-01 to 2017-12-31
The substantial data and biological samples that have been collected through this project have contributed significantly to our understanding of the factors shaping senescence patterns in the Asian elephant, while paving the way for more in-depth molecular analyses. These analyses - which are currently underway - will help to better understand the underlying mechanisms of such patterns and to establish ageing markers as a potential health marker. My results will also contribute to provide new solutions to elephant management and healthcare.
The demographic data collected allowed me to determine factors influencing senescence patterns in the elephant population. First, I examined the effects of advanced maternal age at birth on offspring condition, age-specific reproductive success, and long-term survival. I show that offspring born to older mothers display reduced overall survival and higher age-specific reproductive success, but reduced survival of their own progeny. My results show rare evidence of a persistent effect of maternal age on fitness across generations in a long-lived mammalian population.
I then was interested in investigating how differential sex allocation might impact offspring condition, age-specific reproductive success, and long-term survival. I show that calves born after a male sibling display reduced body mass and lower survival compared with those born after females. The sex of the previous offspring also seems to impact the reproduction of the subsequent siblings, with females born after a male sibling reproducing more slowly. This is the first time such a long-term intergenerational cost has been shown in a mammal species.
Although senescence is often observed in the wild, its underlying mechanistic causes are still poorly understood. I was thus also interested in investigating age-related variations in biological markers of health and their interconnectedness with variations in environmental conditions. I examined how different physiological markers of health (body score index, blood cells count, liver and kidney functions) vary across age. In this study, we see a decline of body condition, immune and liver functions with age; which is the first evidence of senescence on physiological traits in Asian elephants.
The results of this project have been presented at several national and international conferences, including evolutionary biology and physiology symposiums in 2017, as well as invited talks in different Universities (Glasgow – Scotland, Turku – Finland) in 2016 and 2017, which were ideal opportunities to present my research to a broad range of scientists (from ecologists to epidemiologists) interested senescence and its mechanisms.
Finally, the outcomes of this fellowship have led to securing a further 3 years of fellowship funding (TCSM Fellowship at the University of Turku, Finland) for ongoing research in this area.