@article {7020, title = {The mathematical influence on global patterns of biodiversity}, journal = {Ecology and Evolution}, volume = {10}, year = {2020}, pages = {6494-6511}, abstract = {Although we understand how species evolve, we do not appreciate how this process has filled an empty world to create current patterns of biodiversity. Here, we conduct a numerical experiment to determine why biodiversity varies spatially on our planet. We show that spatial patterns of biodiversity are mathematically constrained and arise from the interaction between the species{\textquoteright} ecological niches and environmental variability that propagates to the community level. Our results allow us to explain key biological observations such as (a) latitudinal biodiversity gradients (LBGs) and especially why oceanic LBGs primarily peak at midlatitudes while terrestrial LBGs generally exhibit a maximum at the equator, (b) the greater biodiversity on land even though life first evolved in the sea, (c) the greater species richness at the seabed than at the sea surface, and (d) the higher neritic (i.e., species occurring in areas with a bathymetry lower than 200\ m) than oceanic (i.e., species occurring in areas with a bathymetry higher than 200\ m) biodiversity. Our results suggest that a mathematical constraint originating from a fundamental ecological interaction, that is, the niche{\textendash}environment interaction, fixes the number of species that can establish regionally by speciation or migration.}, keywords = {Biodiversity, ecological niche, large-scale patterns in species richness, models, theory}, doi = {10.1002/ece3.6385}, url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/ece3.6385}, author = {Gr{\'e}gory Beaugrand and Kirby, Richard R and Goberville, Eric} } @article {5810, title = {{Atlantic Multidecadal Oscillations drive the basin-scale distribution of Atlantic bluefin tuna}}, journal = {Science Advances}, volume = {5}, year = {2019}, pages = {eaar6993}, abstract = {

The Atlantic bluefin tuna (hereafter referred to as {\textquotedblleft}bluefin tuna{\textquotedblright}), one of the world{\textquoteright}s most valuable and exploited fish species, has been declining in abundance throughout the Atlantic from the 1960s until the mid-2000s. Following the establishment of drastic management measures, the stock has started to recover recently and, as a result, stakeholders have raised catch quotas by 50{\%} for the period 2017{\textendash}2020. However, stock assessments still omit the natural, long-term variability in the species distribution. Here, we explore the century-scale fluctuations in bluefin tuna abundance and distribution to demonstrate a prevailing influence of the Atlantic Multidecadal Oscillation (AMO) to provide new insights into both the collapse of the Nordic bluefin tuna fishery circa 1963 and the recent increase in bluefin tuna abundance in the Northeast Atlantic. Our results demonstrate how climatic variability can modulate the distribution of a large migrating species to generate rapid changes in its regional abundance, and we argue that climatic variability must not be overlooked in stock management plans for effective conservation.

}, issn = {23752548}, doi = {10.1126/sciadv.aar6993}, author = {Robin Faillettaz and Gr{\'e}gory Beaugrand and Goberville, Eric and Richard R Kirby} } @article {5833, title = {{Prediction of unprecedented biological shifts in the global ocean}}, journal = {Nature Climate Change}, volume = {9}, year = {2019}, month = {mar}, pages = {237{\textendash}243}, abstract = {

Impermanence is an ecological principle1 but there are times when changes occur nonlinearly as abrupt community shifts (ACSs) that transform the ecosystem state and the goods and services it provides2. Here, we present a model based on niche theory3 to explain and predict ACSs at the global scale. We test our model using 14 multi-decadal time series of marine metazoans from zooplankton to fish, spanning all latitudes and the shelf to the open ocean. Predicted and observed fluctuations correspond, with both identifying ACSs at the end of the 1980s4,5,6,7 and 1990s5,8. We show that these ACSs coincide with changes in climate that alter local thermal regimes, which in turn interact with the thermal niche of species to trigger long-term and sometimes abrupt shifts at the community level. A large-scale ACS is predicted after 2014{\textemdash}unprecedented in magnitude and extent{\textemdash}coinciding with a strong El Ni{\~n}o event and major shifts in Northern Hemisphere climate. Our results underline the sensitivity of the Arctic Ocean, where unprecedented melting may reorganize biological communities5,9, and suggest an increase in the size and consequences of ACS events in a warming world.

}, issn = {1758-678X}, doi = {10.1038/s41558-019-0420-1}, url = {http://www.nature.com/articles/s41558-019-0420-1}, author = {Gr{\'e}gory Beaugrand and Alessandra Conversi and Angus Atkinson and Jim E. Cloern and Sanae Chiba and Serena Fonda-Umani and Richard R Kirby and Greene, C. H. and Goberville, Eric and Otto, S. A. and Philip Chris Reid and Stemmann, L. and Martin Edwards} } @article {5812, title = {{Marine biodiversity and the chessboard of life}}, journal = {PLoS ONE}, volume = {13}, year = {2018}, abstract = {

{\textcopyright} 2018 Beaugrand et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Species richness is greater in places where the number of potential niches is high. Consequently, the niche may be fundamental for understanding the arrangement of life and especially, the establishment and maintenance of the well-known Latitudinal Biodiversity Gradient (LBG). However, not all potential niches may be occupied fully in a habitat, as measured by niche vacancy/saturation. Here, we theoretically reconstruct oceanic biodiversity and analyse modeled and observed data together to examine patterns in niche saturation (i.e. the ratio between observed and theoretical biodiversity of a given taxon) for several taxonomic groups. Our results led us to hypothesize that the arrangement of marine life is constrained by the distribution of the maximal number of species{\textquoteright} niches available, which represents a fundamental mathematical limit to the number of species that can co-exist locally. We liken this arrangement to a type of chessboard where each square on the board is a geographic area, itself comprising a distinct number of sub-squares (species{\textquoteright} niches). Each sub-square on the chessboard can accept a unique species of a given ecological guild, whose occurrence is determined by speciation/extinction. Because of the interaction between the thermal niche and changes in temperature, our study shows that the chessboard has more sub-squares at mid-latitudes and we suggest that many clades should exhibit a LBG because their probability of emergence should be higher in the tropics where more niches are available. Our work reveals that each taxonomic group has its own unique chessboard and that global niche saturation increases when organismal complexity decreases. As a result, the mathematical influence of the chessboard is likely to be more prominent for taxonomic groups with low (e.g. plankton) than great (e.g. mammals) biocomplexity. Our study therefore reveals the complex interplay between a fundamental mathematical constraint on biodiversity resulting from the interaction between the species{\textquoteright} ecological niche and fluctuations in the environmental regime (here, temperature), which has a predictable component and a stochastic-like biological influence (diversification rates, origination and clade age) that may alter or blur the former.

}, issn = {19326203}, doi = {10.1371/journal.pone.0194006}, author = {Gr{\'e}gory Beaugrand and Christophe Luczak and Goberville, Eric and Richard R Kirby} } @article {5814, title = {{Climate change and the ash dieback crisis}}, journal = {Scientific Reports}, volume = {6}, year = {2016}, abstract = {

{\textcopyright} The Author(s) 2016. Beyond the direct influence of climate change on species distribution and phenology, indirect effects may also arise from perturbations in species interactions. Infectious diseases are strong biotic forces that can precipitate population declines and lead to biodiversity loss. It has been shown in forest ecosystems worldwide that at least 10{\%} of trees are vulnerable to extinction and pathogens are increasingly implicated. In Europe, the emerging ash dieback disease caused by the fungus Hymenoscyphus fraxineus, commonly called Chalara fraxinea, is causing a severe mortality of common ash trees (Fraxinus excelsior); this is raising concerns for the persistence of this widespread tree, which is both a key component of forest ecosystems and economically important for timber production. Here, we show how the pathogen and climate change may interact to affect the future spatial distribution of the common ash. Using two presence-only models, seven General Circulation Models and four emission scenarios, we show that climate change, by affecting the host and the pathogen separately, may uncouple their spatial distribution to create a mismatch in species interaction and so a lowering of disease transmission. Consequently, as climate change expands the ranges of both species polewards it may alleviate the ash dieback crisis in southern and occidental regions at the same time.

}, issn = {20452322}, doi = {10.1038/srep35303}, author = {Goberville, Eric and Nina-Coralie Hautek{\`e}ete and Richard R Kirby and Yves Piquot and Christophe Luczak and Gr{\'e}gory Beaugrand} } @article {5813, title = {{Global impacts of the 1980s regime shift}}, journal = {Global Change Biology}, volume = {22}, year = {2016}, abstract = {

{\textcopyright} 2016 John Wiley {\&} Sons Ltd. Despite evidence from a number of Earth systems that abrupt temporal changes known as regime shifts are important, their nature, scale and mechanisms remain poorly documented and understood. Applying principal component analysis, change-point analysis and a sequential t-test analysis of regime shifts to 72 time series, we confirm that the 1980s regime shift represented a major change in the Earth{\textquoteright}s biophysical systems from the upper atmosphere to the depths of the ocean and from the Arctic to the Antarctic, and occurred at slightly different times around the world. Using historical climate model simulations from the Coupled Model Intercomparison Project Phase 5 (CMIP5) and statistical modelling of historical temperatures, we then demonstrate that this event was triggered by rapid global warming from anthropogenic plus natural forcing, the latter associated with the recovery from the El Chich{\'o}n volcanic eruption. The shift in temperature that occurred at this time is hypothesized as the main forcing for a cascade of abrupt environmental changes. Within the context of the last century or more, the 1980s event was unique in terms of its global scope and scale; our observed consequences imply that if unavoidable natural events such as major volcanic eruptions interact with anthropogenic warming unforeseen multiplier effects may occur.

}, keywords = {Climate, Earth systems, Global change, Regime shift, Statistical analysis, Time series, Volcanic forcing}, issn = {13652486}, doi = {10.1111/gcb.13106}, author = {Philip Chris Reid and Renata E. Hari and Gr{\'e}gory Beaugrand and David M. Livingstone and Christoph Marty and Dietmar Straile and Jonathan Barichivich and Goberville, Eric and Rita Adrian and Yasuyuki Aono and Ross Brown and James Foster and Pavel Groisman and Pierre H{\'e}laou{\"e}t and Huang-Hsiung Hsu and Richard R Kirby and Jeff Knight and Alexandra Kraberg and Jianping Li and Tzu-Ting Lo and Ranga B. Myneni and Ryan P. North and Alan J. Pounds and Tim Sparks and Ren{\'e} St{\"u}bi and Yongjun Tian and Karen H. Wiltshire and Dong Xiao and Zaichun Zhu} } @article {5817, title = {{Future vulnerability of marine biodiversity compared with contemporary and past changes}}, journal = {Nature Climate Change}, volume = {5}, year = {2015}, abstract = {

{\textcopyright} 2015 Macmillan Publishers Limited. Many studies have implied significant effects of global climate change on marine life. Setting these alterations into the context of historical natural change has not been attempted so far, however. Here, using a theoretical framework, we estimate the sensitivity of marine pelagic biodiversity to temperature change and evaluate its past (mid-Pliocene and Last Glacial Maximum (LGM)), contemporaneous (1960-2013) and future (2081-2100; 4 scenarios of warming) vulnerability. Our biodiversity reconstructions were highly correlated to real data for several pelagic taxa for the contemporary and the past (LGM and mid-Pliocene) periods. Our results indicate that local species loss will be a prominent phenomenon of climate warming in permanently stratified regions, and that local species invasion will prevail in temperate and polar biomes under all climate change scenarios. Although a small amount of warming under the RCP2.6 scenario is expected to have a minor influence on marine pelagic biodiversity, moderate warming (RCP4.5) will increase by threefold the changes already observed over the past 50 years. Of most concern is that severe warming (RCP6.0 and 8.5) will affect marine pelagic biodiversity to a greater extent than temperature changes that took place between either the LGM or the mid-Pliocene and today, over an area of between 50 (RCP6.0: 46.9-52.4{\%}) and 70{\%} (RCP8.5: 69.4-73.4{\%}) of the global ocean.

}, issn = {17586798}, doi = {10.1038/nclimate2650}, author = {Gr{\'e}gory Beaugrand and Martin Edwards and Virginie Raybaud and Goberville, Eric and Richard R Kirby} } @article {5818, title = {{Marine biological shifts and climate}}, journal = {Proceedings of the Royal Society B: Biological Sciences}, volume = {281}, year = {2014}, pages = {20133350}, abstract = {

Phenological, biogeographic and community shifts are among the reported responses of marine ecosystems and their species to climate change. However, despite both the profound consequences for ecosystem functioning and ser- vices, our understanding of the root causes underlying these biological changes remains rudimentary. Here, we show that a significant proportion of the responses of species and communities to climate change are determinis- tic at some emergent spatio-temporal scales, enabling testable predictions and more accurate projections of future changes.We propose a theory based on the concept of the ecological niche to connect phenological, biogeographic and long-term community shifts. The theory explains approximately 70{\%} of the phenological and biogeographic shifts of a key zooplankton Calanus finmarch- icus in the North Atlantic and approximately 56{\%} of the long-term shifts in copepods observed in the North Sea during the period 1958{\textendash}2009.

}, keywords = {environmental science}, issn = {1471-2954}, author = {Gr{\'e}gory Beaugrand and Goberville, Eric and Christophe Luczak and Richard R Kirby} }