Resilience comes from deep evolutionary history, not recent environmental instability

The lead author, James Cant, and senior author, Rob Salguero-Gomez, monitoring the responses of corals to disturbances in Southern Japan

Image: Maria Beger

Adapting to our increasingly changing planet is critical for species’ persistence. Climate change and other human-induced pressures such as pollution or habitat loss expose organisms to ever more variable environments – which means populations need to be resilient to these fluctuations.

We might expect populations that have experienced disturbance in the recent past to have evolved resilience from it, allowing them to respond more effectively in the future. However, new research shows that there is no evidence to suggest this is true.

A team of researchers in Associate Professor Rob Salguero-Gómez’ group (SalGo Team) at Oxford Biology, in collaboration with the University of Leeds, investigated the resilience of hundreds of animal and plant species worldwide (accessible in an online database curated at the Department of Biology of Oxford). They developed a system to measure and characterise the ability of these populations to respond to different kinds of disturbances. The SalGo team then developed a model to test whether the variability in climate over the past few decades could predict these metrics of adaptability. Dr James Cant, the lead author of the study, said:

We discovered that past exposure to more variable environments doesn't guarantee a population’s ability to resist, compensate (i.e. take advantage of disturbances, such as in fire-adapted species), or recover following future disturbances. Instead, the resilience attributes of closely related species was a better indicator of population resilience.

This finding has important implications for management plans and the Sustainable Development Goals stated by the UN, as many of these SDGs acknowledge the need to preserve the resilience of ecological systems to achieve their goals. Management of ecological systems (urban parks, farms, natural parks, etc.) needs to be carefully re-thought, particularly when considering rewilding, as the evidence shows that the past is – in this case – not the key to the future. Associate Professor Rob Salguero-Gómez said:

Beyond the fundamental implications for our understanding of the ecology of species in the Anthropocene, our findings have key implications for the way management plans are implemented. We must carefully rethink whether one can assume that systems will respond to disturbances in the same way they did just a short few decades ago. Furthermore, by rewilding species that might have gone locally extinct at a given area in recent decades, we might still be forcing them to a second local extinction, if we don’t carefully manage the ecological system, and we don’t select for species of high resilience to current and projected disturbance regimes.

Resistance to disturbance is most seen in species that invest more in survival instead of reproduction. Reproduction is a costly investment, and one that typically comes at the price of an individual’s own body maintenance. During times of lower resource availability, being able to rely on viable individuals surviving allows populations to mitigate the loss of other individuals. Somewhat in contrast, short generation times can facilitate a population’s recovery by allowing for rapid growth. These strategies influence resilience in different ways, but are both associated with the deeper history and adaptation of species rather than recent environmental patterns. This insight suggests that we may need to look further back into the history of species to unravel the impacts of unstable environments on the resilience of populations.

The researchers are now expanding this work by looking at resilience across dozens of populations within two species: a herbaceous plant and a frog. This work will allow them to untangle the effects that disturbance has had within species, between populations with high adaptive potential, that have experienced different levels of environmental flux.

The framework used in this line of research will be further expanded to accommodate different disturbance regimes, examine the role of deep time, and integrate resilience across scales of biological organisation using experimental manipulations on grassland systems thanks to a new NERC Pushing the Frontiers grant to Rob Salguero-Gómez.

Video: by Rob Salguero-Gómez. Researchers surveying corals in Japan, where they are evaluating the degree of resilience to climate extremes.

To read more about this research, published in Ecology Letters, visit: https://onlinelibrary.wiley.com/doi/10.1111/ele.14234