Biology subjects

Prunier, J. G.

Publications and source records attributed to Prunier, J. G..

9 recordsLinked to original sources

bioRxiv2026

Warming and predation drive rapid evolution of ecosystem functioning but not functional traits

Global environmental change can rapidly reshape phenotypic trait distributions through adaptive and neutral processes. Yet, disentangling their relative contributions remains a major challenge, particularly for traits underpinning ecosystem functioning. Using a two-year mesocosm study, we experimentally evolved Asellus aquaticus under contrasting temperature and predation regimes to test how the joint influence of these global change pressures shape the evolution of traits and ecosystem functioning. We show that classic functional traits (body size and metabolic rate) showed no evidence of divergent evolution across evolutionary conditions, while ecosystem function itself, namely decomposition rate, has evolved rapidly and differently depending on evolutionary conditions, with the highest decomposition rate observed for Asellus populations exposed to high temperatures in the absence of their predator. A Pst/Fst comparison revealed that divergence in metabolic rate among evolutionary conditions was mainly driven by genetic drift, whereas, for body mass and decomposition rate, non-neutral processes (natural selection and/or plasticity) were also involved, albeit in a different way. By demonstrating that predation and temperature can influence the evolution of an ecosystem function over a few generations, this study represents an important first step toward uncovering the combined effects of global change on the eco-evolutionary dynamics of ecosystems.

evolutionary biology↗

bioRxiv2024

GENETIC DIVERSITY AFFECTS ECOSYSTEM FUNCTIONS ACROSS TROPHIC LEVELS AS MUCH AS SPECIES DIVERSITY, BUT IN AN OPPOSITE DIRECTION

Understanding the relationships between biodiversity and ecosystem functioning stands as a cornerstone in ecological research. Extensive evidence now underscores the profound impact of species loss on the stability and dynamics of ecosystem functions. However, it remains unclear whether the loss of genetic diversity within key species yield similar consequences. Here, we delve into the intricate relationship between species diversity, genetic diversity, and ecosystem functions across three trophic levels --primary producers, primary consumers, and secondary consumers-- in natural aquatic ecosystems. Our investigation involves estimating species diversity and genome-wide diversity -gauged within three pivotal species-within each trophic level, evaluating seven key ecosystem functions, and analyzing the magnitude of the relationships between biodiversity and ecosystem functions (BEFs). We found that, overall, the absolute effect size of genetic diversity on ecosystem functions mirrors that of species diversity in natural ecosystems. We nonetheless unveil a striking dichotomy: while genetic diversity was positively correlated with various ecosystem functions, species diversity displays a negative correlation with these functions. These intriguing antagonist effects of species and genetic diversity persists across the three trophic levels (underscoring its systemic nature), but were apparent only when BEFs were assessed within trophic levels rather than across them. This study reveals the complexity of predicting the consequences of genetic and species diversity loss under natural conditions, and emphasizes the need for further mechanistic models integrating these two facets of biodiversity.

ecology↗

bioRxiv2021

Barrier mitigation measures trigger the rapid recovery of genetic connectivity in five freshwater fish species

Rivers are heavily fragmented by man-made instream barriers such as dams and weirs. This hyper-fragmentation is a major threat to freshwater biodiversity and restoration policies are now adopted worldwide to mitigate these impacts. However, there is surprisingly little feedback on the efficiency of barrier mitigation measures in restoring riverine connectivity, notably for non-migratory fish species. Here, we implemented a "before-after genetic monitoring" of the restoration of 11 weirs in France using a dedicated genetic index of fragmentation (the FINDEX), with a focus on five fish species from two genera. We found that most obstacles actually had a significant impact on connectivity before restoration, especially the highest and steepest ones, with an overall barrier effect of about 51% of the maximal theoretical impact. Most importantly, we demonstrated for the first time that mitigation measures such as dam removal or fish pass creation significantly and rapidly improved connectivity, with -for some barriers-a complete recovery of the genetic connectivity in less than twelve months. Our study provides a unique and strong proof-of-concept that barrier removal is an efficient strategy to restore riverine connectivity and that molecular tools can provide accurate measures of restoration efficiency within a few months. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=80 SRC="FIGDIR/small/471259v1_ufig1.gif" ALT="Figure 1"> View larger version (17K): org.highwire.dtl.DTLVardef@1b9aa38org.highwire.dtl.DTLVardef@5654daorg.highwire.dtl.DTLVardef@1dceedborg.highwire.dtl.DTLVardef@1c56cd1_HPS_FORMAT_FIGEXP M_FIG C_FIG

ecology↗

bioRxiv2019

Loss of genetic diversity in wild fish populations reduces biomass stability over time.

Genetic diversity sustains species adaptation. However, it may also support key ecosystems functions and services that can be altered by the worldwide loss of genetic diversity. Here, using long-term wild fish data, we demonstrate that populations with high genetic diversity do not reach higher biomasses than populations with low genetic diversity. Nonetheless, populations with high genetic diversity have much more stable biomasses over recent decades than populations having suffered from genetic erosion, which has implications for the provision of ecosystem services and the risk of population extinction. Our results strengthen the importance of adopting prominent environmental policies to conserve this important biodiversity facet.

ecology↗

bioRxiv2019

Patterns of gene flow across multiple anthropogenic infrastructures: insights from a multi-species approach

1.Large-scale Transportation Infrastructures (LTIs) are among the main determinants of landscape fragmentation, with strong impacts on animal dispersal movements and metapopulation functioning. Although the detection of LTIs impacts is now facilitated by landscape genetic tools, studies are often conducted on a single species, although different species might react differently to the same obstacle. Multi-specific approaches are thus required to get a better overview of the impacts of human-induced fragmentation. We surveyed four species (a snake, an amphibian, a butterfly and a ground-beetle) in a landscape fragmented by six LTIs: a motorway, a railway, a country road, a gas pipeline, a power line and a secondary road network. We showed that half of the overall explained genetic variability across all species was due to LTIs. While the butterfly was seemingly not impacted by any LTI, the genetic structure of the three other species was mostly influenced by roads, motorway and railway. The power line did not affect any species and the gas pipeline only impacted gene flow in the ground-beetle through forest fragmentation, but other LTIs systematically affected at least two species. LTIs mostly acted as barriers but we showed that some LTIs could somehow promote gene flow, embankments probably providing favourable habitats for vertebrate species. Considering the high variability in species response to LTIs, we argue that drawing general conclusions on landscape connectivity from the study of a single species may lead to counterproductive mitigation measures and that multi-species approaches should be more systematically considered in conservation planning.

ecology↗

bioRxiv2019

Quantifying The Individual Impact Of Artificial Barriers In Freshwaters: A Standardized And Absolute Index Of Genetic Connectivity

Fragmentation by artificial barriers is an important threat to freshwater biodiversity. Mitigating the negative aftermaths of fragmentation is of crucial importance, and it is now essential for environmental managers to benefit from a precise estimate of the individual impact of weirs and dams on river connectivity. Although the indirect monitoring of fragmentation using molecular data constitutes a promising approach, it is plagued with several constraints preventing a standardized and individual quantification of barrier effects. Indeed, observed levels of genetic differentiation depend on both the age of the obstacle and the effective size of the populations it separates, making difficult comparisons of the actual barrier effect of different obstacles. Here, we developed a standardized genetic index of fragmentation (FINDEX), allowing an absolute and independent assessment of the individual effects of obstacles on connectivity. The FINDEX is the standardized ratio (expressed as a percentage) between the observed genetic differentiation between pairs of populations located on either side of an obstacle and the genetic differentiation expected if this obstacle completely prevented gene flow. The expected genetic differentiation is calculated from simulations taking into account two nuisance parameters: the number of generations since barrier creation (the age of the obstacle) and the expected heterozygosity of the targeted populations, a proxy for effective population sizes. Using both simulated and published empirical datasets, we explored and discussed the validity and the limits of the FINDEX. We demonstrated that it allows quantifying genetic effects of fragmentation only from a few generations after barrier creation and provides valid comparisons among populations (or species) of different effective populations sizes and obstacles of different ages. The computation of the FINDEX requires a minimum amount of fieldwork and genotypic data, and solves some of the difficulties inherent to the study of artificial fragmentation in rivers and potentially in other ecosystems. This makes the FINDEX a promising and objective tool for managers aiming at at planning restoration programs and at evaluating the efficiency of these programs.

ecology↗

bioRxiv2019

Demography, genetic, and extinction process in a spatially structured population of lekking bird

Understanding the mechanisms underlying biological extinctions is a critical challenge for conservation biologists. Both deterministic (e.g. habitat loss, fragmentation) and stochastic (i.e. demographic stochasticity, Allee effect) demographic processes are involved in population decline. Simultaneously, a decrease of population size has far-reaching consequences for genetics of populations by increasing the risk of inbreeding and the effects of genetic drift, which together inevitably results in a loss of genetic diversity and a reduced effective population size (Ne). These genetic factors may retroactively affect vital rates (a phenomenon coined inbreeding depression), and therefore reduce population growth and accelerate the extinction process of small populations. To date, few studies have simultaneously examined the demographic and genetic mechanisms driving the extinction of wild populations, and have most of the time neglected the spatial structure of populations. In this study, we examined demographic and genetic factors involved in the extinction process of a spatially structured population of a lekking bird, the western capercaillie (Tetrao urogallus). To address this issue, we collected capture-recapture and genetic data over a 6-years period in Vosges mountains, France. Our study showed that the population of T. urogallus experienced a severe decline between 2010 and 2015. We did not detect any Allee effect on survival and recruitment. By contrast, individuals of both sexes dispersed to avoid small leks, suggesting a behavioral response to a mate finding Allee effect. In parallel to this demographic decline, the population showed a low genetic diversity and high inbreeding. In addition, the effective population sizes at both lek and population levels was low. Despite this, we did not detected evidence of inbreeding depression: neither survival nor recruitment were affected by individual inbreeding level. Our study underlines the benefit from combining demographic and genetic approaches to investigate processes that are involved in biological extinctions.

ecology↗

bioRxiv2019

Kin-dependent dispersal influences relatedness and genetic structuring in a lek system

Kin selection and dispersal play a critical role in the evolution of cooperative breeding systems. Limited dispersal dramatically increases relatedness in spatially structured populations (population viscosity), with the result that neighbours tend to be genealogical relatives. Yet the increase in neighbours performance through altruistic interaction may also result in habitat saturation and thus exacerbate local competition between kin. Our goal was to detect the footprint of kin selection and competition by examining the spatial structure of relatedness and by comparing non-effective and effective dispersal in a population of a lekking bird, Tetrao urogallus. For this purpose, we analysed capture-recapture and genetic data collected over a 6-year period on a spatially structured population of T. urogallus in France. Our findings revealed a strong spatial structure of relatedness in males. They also indicated that the population viscosity allowed male cooperation through two non-exclusive mechanisms. First, at their first lek attendance, males aggregate in a lek composed of relatives. Second, the distance corresponding to non-effective dispersal dramatically outweighed effective dispersal distance, which suggests that dispersers incur high post-settlement costs. These two mechanisms result in strong population genetic structuring in males. In females, our findings revealed a lower level of spatial structure of relatedness and genetic structure in respect to males. Additionally, non-effective dispersal and effective dispersal distances in females were highly similar, which suggests limited post-settlement costs. These results indicate that kin-dependent dispersal decisions and costs are factors driving the evolution of cooperative courtship and have a genetic footprint in wild populations.

ecology↗

bioRxiv2018

Intraspecific genetic and phenotypic diversity: parallel processes and correlated patterns?

Intraspecific diversity plays a key role for evolutionary and ecological dynamics. It is the raw material on which acts selection, it improves species and communities resilience to disturbance and it affects the way species modulate their biotic and abiotic environment. Understanding patterns and underlying determinants of genetic and phenotypic intraspecific diversity is therefore of critical importance for ecological, evolutionary and conservation sciences. Here, focusing on two freshwater fish species (Gobio occitaniae and Phoxinus phoxinus) sampled across a large river basin (the Garonne-Dordogne river basin, France), we used causal analyses to test for genetic-phenotypic intraspecific diversity correlations (GPIDCs) and unravel the processes underlying intraspecific diversity patterns. Genetic diversity was assessed using microsatellite markers and phenotypic diversity was assessed through geometric morphometrics. We found disparities in the distribution of genetic and phenotypic diversity in the two species, suggesting higher level of local adaptation in G. occitaniae, and our results revealed common and contrasted processes shaping diversity at the - and {beta}-level. At the -level, we found no GPIDC in both species despite common relations between isolation and genetic and phenotypic -diversity in G. occitaniae. At the {beta}-level, we found no GPIDC in P. phoxinus but we found a positive GPIDC in G. occitaniae. This correlation appeared to be caused by a direct impact of one facet of intraspecific diversity on the other, and we speculated that it could originate from positive assortative mating. Studying neutral genetic diversity and phenotypic diversity within an integrative framework appears as a valuable way of deciphering the complex and diverse impacts of neutral and adaptive processes on intraspecific diversity patterns.

evolutionary biology↗