Life history traits mediate elevational adaptation in a perennial alpine plant

Abstract

SummarySpatially divergent natural selection drives adaptation to contrasting environments and the evolution of ecotypes. Understanding this process in perennial plants is challenging because natural selection acts on multiple life history traits linked by fitness trade-offs.In a multi-year reciprocal transplant experiment of high and low elevation populations of the alpine carnationDianthus carthusianorumin the Central Alps, we tested how different stages of the life cycle contribute to adaptation. Moreover, we used matrix population models to infer the specific contributions of individual life stages to fitness, coupled with trade-off analyses.We found genotype x environment interactions consistent with elevational adaptation both in single fitness components linked to reproduction and survival, and in integrative fitness estimates. Adaptation at low elevation is driven by early reproduction, in contrast to an opposite strategy at high elevation. Adaptive life-history differences between populations originating from low and high elevations are mediated by environmental effects on plant growth and trade-offs between reproduction and survival.Our work reveals elevational ecotypes of the perennial alpine plantD. carthusianorumthat express alternative life history strategies in response to climatic differences shaping resource allocation.