Ecosystem recovery after climatic extremes enhanced by genotypic diversity

TLDR

Climate change is increasing both mean temperatures and extreme events, and how populations and communities cope with these extremes is a central ecological question, with species diversity known to influence ecosystem functioning and resilience. The study investigates whether genotypic diversity can replace species diversity to buffer a species‑poor coastal ecosystem against extreme climatic events. In a field experiment, increasing genotypic diversity of the seagrass *Zostera marina* raised biomass, plant density, and faunal abundance under near‑lethal temperatures, with effects driven by complementarity rather than selection, and positive impacts on invertebrates indicate genetic diversity benefits higher trophic levels, highlighting the importance of preserving genetic diversity for ecosystem resilience.

Abstract

Contemporary climate change is characterized both by increasing mean temperature and increasing climate variability such as heat waves, storms, and floods. How populations and communities cope with such climatic extremes is a question central to contemporary ecology and biodiversity conservation. Previous work has shown that species diversity can affect ecosystem functioning and resilience. Here, we show that genotypic diversity can replace the role of species diversity in a species-poor coastal ecosystem, and it may buffer against extreme climatic events. In a manipulative field experiment, increasing the genotypic diversity of the cosmopolitan seagrass Zostera marina enhanced biomass production, plant density, and faunal abundance, despite near-lethal water temperatures due to extreme warming across Europe. Net biodiversity effects were explained by genotypic complementarity rather than by selection of particularly robust genotypes. Positive effects on invertebrate fauna suggest that genetic diversity has second-order effects reaching higher trophic levels. Our results highlight the importance of maintaining genetic as well as species diversity to enhance ecosystem resilience in a world of increasing uncertainty.