Biology subjects

Comte, L.

Publications and source records attributed to Comte, L..

3 recordsLinked to original sources

bioRxiv2026

Dispersal rate limits range expansion rate only when it is slower than climate velocity

Low dispersal ability might limit a species capacity to track its climate preferences across the landscape, yet evidence that low dispersal slows species range shifts under contemporary climate change remains contentious. Here we develop a new hypothesis under which we expect variation in dispersal ability to affect range expansion rates only when climate velocity exceeds dispersal rates, which is logical yet rarely applied because it requires a common yardstick to compare rates. We test this hypothesis using empirical relationships between dispersal ability, local range expansion rate, and the velocity of isotherm shifts in terrestrial plants and birds, all estimated in km/yr. In 370 range shifts, we found that range expansion rates were best explained by the slower of either a species dispersal rate or the velocity of isotherm shifts, as predicted under our hypothesis. Furthermore, when species dispersal rates were slower than the velocity of isotherm shifts, we found that dispersal ability positively affects range shift rates. Substantial variation in range expansion rates remained unexplained, indicating that additional factors influence range shift dynamics. Our results provide new clarity when understanding the role of dispersal ability on variation in range shift rates and emphasize the importance of evaluating dispersal capacity relative to climatic change exposure when testing hypotheses about species responses to ongoing environmental change. Significance StatementSpecies dispersal ability is widely thought to limit biodiversity redistribution in response to climate change, but we still lack a clear understanding of when or for which species dispersal limitations matter. Using hundreds of range expansion rates documented over the 10 last decades for terrestrial birds and plants together with their dispersal rates, in common units of km/yr, we show that dispersal ability slows climate-mediated range expansion, but that dispersal limitations occur only when the rates of climate change are faster than the ability of species to redistribute. So far, many species display dispersal rates higher than the velocity of climate change but dispersal limitations may become more pronounced in the future.

ecology↗

bioRxiv2024

Degradation of fish food webs in the anthropocene

The Anthropocene is marked by profound changes in biodiversity and the ecosystems in which species live 1-4. A primary signature of this change is the often rapid change in species composition through time (i.e., species turnover) rather than changes in the numbers of species per se 5-7. Less well known, however, is which types of species are winning and which are losing as ecosystems change through time 8,9, as well as whether and how these changes influence higher-level processes in the food webs in which species are embedded 10,11. Here, we combine a compilation of long-term observations of [~]15,000 freshwater and marine fish communities surveyed for 1949-2019 years, together with information about their diets and trophic status in order to evaluate how the food webs in which these fish communities are embedded are changing through time. We found widespread alteration to fish food web topology and functioning. This includes an increase in connectance and generalism in food webs, which has led to greater predation pressure, as indicated by higher diet overlap and increased prey vulnerability. We also identified a decrease in modularity, which has reduced the compartmentalization within local networks. These changes extend across the trophic structure of food webs, causing a cascading shift in the proportion of species across trophic levels. Our study highlights the complex responses of biodiversity change of fish food webs in the Anthropocene, which can ultimately influence the functions of these ecosystems and human well-being 12,13.

ecology↗

bioRxiv2019

Species better track the shifting isotherms in the oceans than on lands

Despite mounting evidence of species redistribution as climate warms, our knowledge of the coupling between species range shifts and isotherm shifts is limited. Compiling a global geo-database of 30,534 range shifts from 12,415 taxa, we show that only marine taxa closely track the shifting isotherms. In the oceans, the velocity of isotherm shifts interacts synergistically with anthropogenic disturbances and baseline temperatures such that isotherm tracking by marine life happens either in warm and undisturbed waters (e.g. Central Pacific Basin) or in colder waters where human activities are more pronounced (e.g. North Sea). On lands, increasing anthropogenic activities and temperatures negatively impact the capacity of terrestrial taxa to track isotherm shifts in latitude and elevation, respectively. This suggests that terrestrial taxa are lagging behind the shifting isotherms, most likely due to their wider thermal safety margin, more constrained physical environment for dispersal and higher availability of thermal microrefugia at shorter distances.

ecology↗