Susana Clusella-Trullas
Susana Clusella-Trullas

Dr. Susana Clusella-Trullas is an Associate Professor of Physiological Ecology in the Department of Botany and Zoology and core team member of the Centre for Invasion Biology at Stellenbosch University. Dr. Clusella-Trullas describes for us her experience at the “Species on the Move” conference in Kruger National Park, South Africa.

I have just returned from a great conference called “Species on the Move” in Kruger National Park, South Africa (22-26 July 2019, convened by Gretta Pecl from the University of Tasmania, Australia and Warwick Sauer from Rhodes University, South Africa), and thought I will give a few (not exhaustive!) highlights from the meeting. For those that are not familiar with this meeting, Species on the Move is an international conference that addresses the redistribution of species around the globe resulting from climate change.

Dr. Mohlamatsane Mokhatla (from South African National Parks, South Africa) presenting his research on predictions of climate-driven distributions of three African temperate frogs using models that incorporate physiology and performance data.
Dr. Mohlamatsane Mokhatla (from South African National Parks, South Africa) presenting his research on predictions of climate-driven distributions of three African temperate frogs using models that incorporate physiology and performance data.

The impacts of changes in species distributions are ubiquitous and affect multiple dimensions, including ecological aspects such as disruption of local biotic communities, species interactions, and ecosystem functioning with implications for food security and human health. These changing distributions can also create new opportunities for some species, such as alien species, symbiotic organisms and vectors of disease. Thus, this meeting is multifaceted in nature and included talks pertaining to detection, attribution and prediction of species range shifts, as well as indigenous knowledge, governance, conservation and policy. As an eco-physiologist, my interest lies within the biological realm of species responses and how we can further integrate mechanisms into models of species range shifts. Below are some topics and talks that stood out for me, and that may be of interest to fellow functional ecologists.

As species move with climate change and extend or contract their ranges, one pertinent question is to what extent these species fill their thermal niches. Dr. Malin Pinsky gave an interesting talk that summarized thermal safety margin indices (the difference between upper thermal limits and extreme habitat temperatures) across both marine and terrestrial species (>300 species). He showed that while terrestrial species tend to have lower safety margins in the subtropics and temperate areas, marine species have the lowest margins in the tropics. Marine species also had overall smaller thermal safety margins compared to terrestrial species especially if the latter had access to refuges. Marine tropical species are encountering increasingly warmer or stressful conditions and several presenters referred to the current “tropicalisation” of marine temperate ecosystems, as tropical species shift into several temperate regions of the world.   

The drivers of species redistributions are not limited to climate variables, and incorporate other abiotic factors such as land-use change, but also biotic interactions. Additional abiotic aspects were illustrated by Fengyi Guo’s presentation, which highlighted how forest cover (baseline level and change) are also essential predictors of the rate of species elevational shifts worldwide. In addition, for species with complex or sedentary life-styles, factors that facilitate movement at critical stages can be essential. For example, river flow, fire regimes or wind patterns may shape the redistribution of such species. Matthew Kling presented an interesting talk in which he showed that the overlay of wind direction and climate gradients across large-scales can reveal landscapes where wind may either hinder or facilitate seed dispersal. He also had great visual figures to show these patterns!

Species that are unable to adapt locally, buffer climate variability via plasticity (including behavior) or change their phenology will need to disperse. Once they move, species will also need to reproduce and persist. What factors and traits enable species to be more mobile and establish are myriad and depends on the context and species investigated. Dr. Emily Moran explained how genetic markers have been used to better estimate distance of non-wind dispersed plant species and how these techniques can provide estimates that are higher than those measured with seed traps. In another fascinating talk, Dr. I-Ching Chen showed that despite climate conditions mediating the density of a burying beetle species and the speed at which it could detect resources along an elevation gradient, temperature also mediated the interaction with a fly species that competed for the same resources. Interestingly, the complexity of these interacting factors resulted in a transition from interference to exploitative competition along the elevational gradient, from the warm to the cold range edge.

These factors emphasize the need to incorporate ecological and evolutionary processes in predictive models of range shifts but also to inform adaptive strategies and mitigate negative impacts such as species extirpations. For example, Dr. Line Bay presented research linking the phenotype to genotype of corals’ bleaching, the genetics underlying heat tolerance and mathematical models simulating coral persistence. This work can be used to enhance coral adaptation to climate change by using adaptive restoration management approaches, such as assisted gene flow and introduction of warm-adapted individuals.

Overall, the meeting was highly stimulating, well attended and with a great selection of speakers and themes. There was also a great diversity of cultures and fields, with a nice mixture of junior (see picture) and senior scientists, managers, policy people and representatives of indigenous communities such as local South African fishers. The exposure to other dimensions (e.g. society and governance) was a real eye-opener and reiterated that the challenges associated with climate change cannot be addressed single-mindedly or without accounting for many feedback processes and interacting pieces that affect the same problem. Still, there is much work to be done! Keep an eye out for the next Species on the Move meeting in Florida 2022.

Missed the conference? Try the resources below: