Macroecology: lessons from the past, forecasting the future

• INT15 • Integrating historical and present drivers to understand recent spatial dynamics of species distribution. > A-C. Anne-Christine MONNET
Content : My talk will focus on the family Poaceae, the fifth largest family of Angiosperms and an ecologically and economically important group present on all continents and in very diverse habitats. Although some recent studies substantially improved our understanding of the radiation of grasses since their origin in warm and closed habitats, the discrepancies observed in the responses of different grass lineages along climatic and latitudinal gradients remain poorly understood. We then gathered functional trait and phylogenetic information for all Poaceae species, c. 11000 species, and geographic information on their native and exotic ranges. Grasses display striking distributional patterns, especially a shallow latitudinal gradient. Richness is concentrated in the warm, wet tropics, but a number of lineages are adapted to cold and arid environments, keeping diversity unusually high there. While current climate gradients strongly determine the distribution of species assemblages at large spatial scales, I will also show the importance of historical drivers to better understand the distribution of species assemblages, especially the distribution of exotic grass species, and discuss the contributions of traits and phylogeny in these studies. • INT16 • Simulating biodiversity > O. Oskar HAGEN
Content : Biodiversity emerges and emerged from ecological and evolutionary forces interacting over an ever-changing world. This complexity of ecological, evolutionary, geological and climatological processes is mirrored in our current fragmented scientific landscape. Recent developments in computer modelling and past climatic reconstructions allow for simulating emergent biodiversity, supporting the formalization and testing of biodiversity theories. As science advances, eco-evolutionary models help us to better grasp how species and populations coped with past changes by connecting the knowledge from multiple fields. For example, present genetic structures and large scale biodiversity patterns such as the latitudinal and longitudinal diversity gradient were reproduced using past environmental reconstructions in tandem with eco-evolutionary rules. Ultimately, this approach might catalyze interdisciplinarity and scientific debate, leading to knowledge that can be used to predict how biodiversity might change under future scenarios. • INT17 • Historical plant introductions predict current insect invasions > A. Aymeric BONNAMOUR
Content : Thousands of insect species have been introduced outside of their native range, causing important damage of ecosystems and human societies. Insects are tightly associated with plants as many of them feed, nest or live on plants. Consequently, the plant trade is one of the main pathways of alien insect introductions. Alien plants also facilitate the establishment and spread of alien insects, in particular of those using plants as hosts. Here, we tested the hypothesis that plant invasions precede insect invasions. We compared the predictive power of historical and current alien plant flows, from 1800 to 2010, and of confounding socio-economic variables on insect invasions at a global scale. We found that current alien insect flows were best explained by the alien plant flows of 1880 rather than by more recent plant flows. Interestingly, trade flows had no effect on insect invasions once alien plant flows were included in the models. Based on the observed time lag between plant and insect invasions, we estimated insect invasion debt worldwide. This debt was most important in the Neotropics, the Afrotropics and Indomalaya, suggesting that many new insect invasions can be expected in these regions over the coming years. Overall, our results highlight the strong link between plant and insect invasions, and show that limiting the introduction, establishment and spread of alien plants will be key to prevent future invasions of both plants and insects. • INT18 • Climatic forcing of global ecosystem changes from the Last Glacial Maximum to the end of the 21st century > T. Timo CONRADI
Content : In this talk I show how a physiological model of plant growth that is forced with climate data can be parametrized using the information contained in species distribution data. Thanks to massive databases on plant species distributions, we can parametrize the growth model for circa 135,000 vascular plant species. I use the growth models to characterize the climatic suitability of geolocations for the different plant growth forms that define terrestrial ecosystems (e.g. evergreen trees, deciduous trees, grasses, succulents, etc.). I then show how the climatic suitability for the growth forms changed from the Last Glacial Maximum to the present and how the climatic suitability for the growth forms will change in the future. I conclude by comparing the magnitudes of future and past changes in climatic suitability, which is useful for understanding the impacts future climatic changes will have on ecosystems. • INT19 • Consequences of biological invasions on functional diversity worldwide > B. Bellard CÉLINE
Content : Biological invasions are one of the main drivers of biodiversity decline worldwide. However, many associated extinctions are yet to occur, meaning that the ecological debt caused by invasive species could be important for biodiversity. We explore extinction scenarios due to invasive species and investigate whether paying off the current extinction debt will shift the global composition of mammals and birds in terms of ecological strategy. We found that 14% of worldwide trait diversity is hosted by invasive-threatened mammals and 40% by invasive-threatened birds, with Neotropical and Oceanian realms being primary risk hotspots. Projected extinctions of invasive-threatened species result in a smaller reduction in ecological strategy space than expected under randomized extinction scenarios. This can be explained by the strong pattern in the clustering of ecological profiles and families impacted by invasive alien species. However, our results confirm that IAS are likely to cause the selective loss of species with unique evolutionary and ecological profiles. Our results also suggest a global shift in species composition away from those with large body mass, which mostly feed in the lower foraging strata and have an herbivorous diet (mammals). Our findings demonstrate the potential impact of biological invasions on trait dimensions of diversity, especially in the Oceanian realm. We therefore call for a more systematic integration of all facets of diversity when investigating the consequences of biological invasions. This would help to anticipate the consequences of losing specific ecological profiles in the invaded community. • INT20 • BioShifts – A database of geographic range shifts for terrestrial and marine taxa under anthropogenic climate change > J. Jonathan LENOIR
Content : Species distribution changes associated with human-mediated climate change have important consequences on ecosystems and human well-being. Despite mounting evidence, our knowledge of the redistribution of life on Earth is still incomplete with only 0.6% of the described biodiversity on Earth for which range shifts have been documented. I will present the BioShifts database which contains 30,534 observations of velocity of range shifts (VRS) for 12,415 taxa, covering 56 taxonomic classes and 20 phyla across both terrestrial and marine systems. This database is clearly biased towards more VRS data for mobile ectotherms, iconic endotherms and seed-bearing plants. Similarly, a strong geographical bias is noticeable towards the most developed regions in the World. Contrary to former meta-analyses and quantitative syntheses on climate-induced species range shifts, I will show the extreme variability in the magnitude and direction of VRS values that is hiding behind averages across broad taxonomic groups (e.g., amphibians, arthropods, birds, insects, mammals, molluscs and plants) or position within the geographic range (i.e., trailing edge, centroid of the range and leading edge). I will also show that VRS values do not necessarily conform to the observed values in the magnitude and direction of velocity of isotherm shifts (VIS), suggesting other determinants behind the great redistribution of life on Earth.