Climate‐driven evolutionary change in reproductive and early‐acting life‐history traits in the perennial grass Festuca ovina

Sarah Trinder,Andrew P Askew,Raj Whitlock,Meghan Avolio

doi:10.1111/1365-2745.13304

Abstract

Abstract Reproductive and early‐acting life‐history traits are likely to be particularly important determinants of plant fitness under a changing climate. There have, however, been few robust tests of the evolution of these traits under chronic climate change in natural ecosystems. Such studies are urgently needed, to evaluate the contribution of evolutionary change to population persistence. Here, we examine climate‐driven evolutionary change in reproductive and early‐acting plant life‐history traits in the long‐lived perennial plant, Festuca ovina. We collected established plants of F. ovina from species‐rich calcareous grassland at the Buxton Climate Change Impacts Laboratory (BCCIL), after 17 years of in situ experimental drought treatment. P1 plants collected from drought‐treated and control (ambient climate) plots at BCCIL were used to create an open‐pollinated F1 progeny array, which was subsequently validated using microsatellite markers to establish a robust bi‐parental pedigree. We measured the timing of germination and seed mass in the F1 progeny, the P1 paternal contribution to F1 offspring (paternal reproductive success), and assessed the effects of flowering time on the mating system. F1 seed with ancestry in drought‐treated plots at BCCIL germinated significantly later than seed derived from individuals from control plots. P1 plants from the drought treatment flowered significantly earlier than those from the control plots in summer 2012, but not in 2013. Male reproductive success was also lower in P1 plants collected from drought plots than those from control plots. Furthermore, our pedigree revealed that mating among parents of the F1 progeny had been assortative with respect to flowering time. Synthesis. Our study shows that chronic drought treatment at Buxton Climate Change Impacts Laboratory has driven rapid evolutionary change in reproductive and early‐acting life‐history traits in Festuca ovina, and suggests that evolutionary differentiation may be reinforced through changes in flowering time that reduce the potential for gene flow.

Highlights

Reproductive and early-acting plant traits defining viability are expected to be pivotal determinants of fitness under a changing climate (Donohue, Casas, Burghardt, Kovach, & Willis, 2010; Etterson & Mazer, 2016)
Our study shows that chronic drought treatment at Buxton Climate Change Impacts Laboratory has driven rapid evolutionary change in reproductive and early-acting life-history traits in Festuca ovina, and suggests that evolutionary differentiation may be reinforced through changes in flowering time that reduce the potential for gene flow
Male reproductive success has been reduced in plants from the drought treatments, as a result of evolutionary changes in reproductive tiller number

Summary

| INTRODUCTION

Reproductive and early-acting plant traits defining viability are expected to be pivotal determinants of fitness under a changing climate (Donohue, Casas, Burghardt, Kovach, & Willis, 2010; Etterson & Mazer, 2016). Female reproductive potential (seed output) can be measured and directly, and responds to abiotic conditions, including CO2 levels, temperature stress and water deficit (Guilioni, Wéry, & Lecoeur, 2003; Prasad, Staggenborg, & Ristic, 2008; Wang, Taub, & Jablonski, 2015) This trait can evolve rapidly (Sultan et al, 2013), over fine spatial scales (Antonovics & Bradshaw, 1970; Snaydon & Davies, 1972, 1976), and in response to microclimatic variation (GonzaloTurpin & Hazard, 2009). We describe the construction and molecular validation of an open-pollinated F1 progeny array from fieldcollected parental plants, to facilitate analysis of heritable droughtinduced evolution We combine this resource with data from common garden experiments to ask whether long-term drought treatment has driven evolutionary changes in key plant traits associated with reproduction, germination and the plant mating system, and to document the nature of drought-induced phenotypic change

| MATERIALS AND METHODS

Findings

| DISCUSSION

| CONCLUSIONS