2020 ESA Annual Meeting (August 3 - 6)

COS 94 Abstract - Community-wide adaptation to 25 years of drought and warming treatments in a grassland ecosystem

Robert Fitt1, Carly J. Stevens2, Emma Sayer3, Stewart Plaistow1, Stephen J. Cornell1, Karen Harper1, Andrew P. Askew1 and Raj Whitlock1, (1)Institute of Integrative Biology, University of Liverpool, Liverpool, United Kingdom, (2)Lancaster Environment Center, Lancaster University, Lancaster, United Kingdom, (3)Lancaster Environment Centre, Lancaster University, Lancaster, United Kingdom
Background/Question/Methods

Adaptation, through evolution or phenotypic plasticity, offers populations the means to resist climate change in situ. How these processes operate in communities of coexisting populations is poorly understood, but this knowledge is crucial in predicting community and ecosystem level responses to environmental change. Focusing on life-history traits, we investigated adaptive responses to climate treatments at the Buxton Climate Change Impacts Lab (BCCIL, Buxton, UK), in coexisting plant species.

The species-rich grassland at BCCIL has been exposed to annual drought, warming and watering treatments for over 25 years. These treatments have led to changes in abundance that can be predicted from species’ functional traits. However, no species, or functional group has yet been extirpated from any of the treatments, suggesting a role for intraspecific adaptation in stabilising the ecosystem. If a change in a functional trait carries the same benefit to fitness across species, then adaptive changes that occur within species in response to climate change should occur in the same direction across species. Furthermore, if these intraspecific changes in phenotype reduce differences in relative fitness between species, then this intraspecific adaptation is expected to stabilise species coexistence at the community level.

We compared life history traits from populations of six common plant species collected from different climate treatments at Buxton in a common garden environment. We hypothesised (i) that evolutionary shifts in phenotype would be prevalent across all species, and (ii) that the direction of the phenotypic change would be in parallel across species, reflecting selection on functional traits that increase fitness.

Results/Conclusions

Our results illustrate evolutionary adaptation to warming or drought in five of the six study species. However, the phenotypic direction of these effects varied between species. Populations of Festuca ovina & Anthoxanthum odoratum from drought treatments demonstrated increased seed mass, relative to control plots. In contrast, populations of Briza media, Helictrichon pratense, & Plantago lanceolata from heating treatment showed increased seed mass relative to the respective control plot populations. Increased seed mass corresponded to increase seedling germination and growth rates, suggesting a fitness benefit to higher seed mass.

Our results supported our hypothesis that intraspecific adaptation to the climate is widespread across coexisting species, but provided no support for parallel shifts in phenotypes across species. Thus, either the same functional traits affect fitness differently in different species, or adaptive phenotypic shifts are generated indirectly by climate change in some species, via species interactions or other environmental effects.