Transient LTRE analysis reveals the demographic and trait?mediated processes that buffer population growth

Abstract

Temporal variation in environmental conditions affects population growth directly via its impacton vital rates, and indirectly through induced variation in demographic structure and phenotypictrait distributions. We currently know very little about how these processes jointly mediate popu-lation responses to their environment. To address this gap, we develop a general transient lifetable response experiment (LTRE) which partitions the contributions to population growth arisingfrom variation in (1) survival and reproduction, (2) demographic structure, (3) trait values and (4)climatic drivers. We apply the LTRE to a population of yellow-bellied marmots (Marmota ?a-viventer) to demonstrate the impact of demographic and trait-mediated processes. Our analysisprovides a new perspective on demographic buffering, which may be a more subtle phenomenathan is currently assumed. The new LTRE framework presents opportunities to improve ourunderstanding of how trait variation in?uences population dynamics and adaptation in stochasticenvironments