Biology subjects

Diagne, C.

Publications and source records attributed to Diagne, C..

6 recordsLinked to original sources

bioRxiv2024

Predicting the global economic costs of biological invasions by tetrapods

Globalisation has steadily accelerated rates of biological invasions worldwide, leading to widespread environmental perturbations that often translate into rapidly expanding socioeconomic costs. Although such monetary costs can be estimated based on the observed effects of invasions, the pathways that lead invasive species to become economically impactful remain poorly understood. Here, we implement the first global-scale test of the hypothesis that adaptive traits that influence demographic resilience predict economic costs, using invasive terrestrial vertebrates as models given their rising impacts and well-catalogued characteristics. Our results reveal that total global costs of invasive tetrapods are conservatively in the tens of billions of dollars, with the vast majority due to damage costs from invasive mammals. These monetary impacts are predicted by longevity, female maturation age, diet and invasional pathway traits, although the directionality of predicted economic impacts also varied by trait across classes. Alarmingly, costs remain unknown for >90% of recorded established alien tetrapods worldwide, and across the majority of invaded countries. These huge socio-economic costs demonstrate the necessity of mitigating tetrapod invasions and filling knowledge gaps. Effective identification of traits predictive of costs among and within these groups can facilitate the prioritisation of resources to efficiently target the most damaging existing and emerging invasive tetrapod species.

ecology↗

bioRxiv2023

Toxoplasma gondii and Trypanosoma lewisi infection in urban small mammals from Cotonou, Benin, with special emphasis on co-infection patterns

A growing number of studies has highlighted the importance of co-infections in eco-evolutionary processes underlying host-parasite interactions and the resulting epidemiology of zoonotic agents. Small mammals, and particularly rodents, are known to be important reservoirs of many zoonotic pathogens, such as Toxoplasma gondii and Trypanosoma lewisi that are responsible for toxoplasmosis and atypical trypanosomiasis in human, respectively. Laboratory experiments on rodent models have shown that primary infection with T. lewisi increases the host susceptibility to other co-infectious parasites, including T. gondii, following an alteration of the immune system. However, data on potential interactions between these parasites in wild small mammals remain scarce. In this study, we estimate the T. lewisi prevalence in 553 small mammals from four localities of Cotonou city, Benin. They were then combined with T. gondii data previously collected on the same individuals in order to investigate the influence of T. lewisi on T. gondii infection, and vice-versa, using cooccurrence tests and Generalized Linear Mixed Models. Despite quite high overall prevalence (32.5% and 15.2% for T. gondii and T. lewisi, respectively), we observed a clear and significant segregation between the two parasites. This may be explained by (i) differences in the species-specific susceptibility of small mammal host species to infection by these two parasites, with R. rattus and M. natalensis being the main reservoirs of T. lewisi while C. olivieri and M. m. domesticus are the main hosts for T. gondii; and/or by (ii) a possibly high mortality in co-infected animal in the wild. Although dedicated experimental studies are required to confirm this pattern, as they stand, our data fail to support that infection of small mammals by one of these two parasites favours widespread infection by the second one in nature.

ecology↗

bioRxiv2022

Small scale geographical variation of three-way relationships between gut microbiota, helminth assemblages and bacterial infections in wild rodent populations

BackgroundDespite its central role in host fitness, the gut microbiota may differ greatly between individuals. This variability is often mediated by environmental or host factors such as diet, genetics, and infections. Recently, a particular attention has been given to the interactions between gut bacteriota and helminths, as these latter could affect host susceptibility to other infections. Further studies are still required to better understand the three-way interactions between gut bacteriota, helminths and other parasites, especially because previous findings have been very variable, even for comparable host-parasite systems. MethodsIn our study, we used the V4 region of the 16S rRNA gene to assess the variability of gut bacteriota diversity and composition in wild populations of a small mammal, the bank vole Myodes glareolus. Four sites were sampled at a regional geographical scale (100 km) along a North-South transect in Eastern France. We applied analyses of community and microbial ecology to evaluate the interactions between the gut bacteriota, the gastro-intestinal helminths and the pathogenic bacteria detected in the spleen. ResultsWe identified important variations of the gut bacteriota composition and diversity among bank voles. They were mainly explained by sampling localities and reflected the North/South sampling transect. In addition, we detected two main enterotypes, that might correspond to contrasted diets. We found geographic variations of the Firmicutes/Bacteroidetes ratio, that correlated positively with body mass index. We found positive correlations between the specific richness of the gut bacteriota and of the helminth community, as well as between the composition of these two communities, even when accounting for the influence of geographical distance. The helminths Aonchotheca murissylvatici, Heligmosomum mixtum and the bacteria Bartonella sp were the main taxa associated with the whole gut bacteriota composition. Besides, changes in relative abundance of particular gut bacteriota taxa were specifically associated with other helminths (Mastophorus muris, Catenotaenia henttoneni, Paranoplocephala omphalodes and Trichuris arvicolae) or pathogenic bacteria. Especially, infections with Neoehrlichia mikurensis, Orientia sp, Rickettsia sp and P. omphalodes were associated with lower relative abundance of the family Erysipelotrichaceae (Firmicutes), while coinfections with higher number of bacterial infections were associated with lower relative abundance of a Bacteroidales family (Bacteroidetes). ConclusionsThese results emphasize complex interlinkages between gut bacteriota and infections in wild animal populations. They remain difficult to generalize due to the strong impact of environment on these interactions, even at regional geographical scales. Abiotic features, as well as small mammal community composition and within host parasite coinfections, should now be considered to better understand the spatial variations observed in the relationships between gut bacteriota, gastro-intestinal helminths and bacterial infections.

ecology↗

bioRxiv2021

Economic costs of biological invasions in the United States

The United States has thousands of invasive species, representing a sizable, but unknown burden to the national economy. Given the potential economic repercussions of invasive species, quantifying these costs is of paramount importance both for national economies and invasion management. Here, we used a novel global database of invasion costs (InvaCost) to quantify the overall costs of invasive species in the United States across spatiotemporal, taxonomic, and socioeconomic scales. From 1960 to 2020, reported invasion costs totaled $4.52 trillion (USD 2017). Considering only observed, highly reliable costs, this total cost reached $1.22 trillion with an average annual cost of $19.94 billion/year. These costs increased from $2.00 billion annually between 1960-1969 to $21.08 billion annually between 2010-2020. Most costs (73%) were related to resource damages and losses ($896.22 billion), as opposed to management expenditures ($46.54 billion). Moreover, the majority of costs were reported from invaders from terrestrial habitats ($643.51 billion, 53%) and agriculture was the most impacted sector ($509.55 billion). From a taxonomic perspective, mammals ($234.71 billion) and insects ($126.42 billion) were the taxonomic groups responsible for the greatest costs. Considering the apparent rising costs of invasions, coupled with increasing numbers of invasive species and the current lack of cost information for most known invaders, our findings provide critical information for policymakers and managers.

ecology↗

bioRxiv2021

Capacity of countries to reduce biological invasions

The extent and impacts of biological invasions on biodiversity are largely shaped by an array of socio-ecological predictors, which exhibit high variation among countries. Yet a global synthetic perspective of how these factors vary across countries is currently lacking. Here, we investigate how a set of five socio-ecological predictors (Governance, Trade, Environmental Performance, Lifestyle and Education, Innovation) explain i) country-level established alien species (EAS) richness of eight taxonomic groups, and ii) country capacity to prevent and manage biological invasions and their impacts. Trade and Governance together best predicted the average EAS richness, increasing variance explained by up to 54% compared to models based on climatic and spatial variables only. Country-level EAS richness increased strongly with Trade, whereas high level of Governance resulted in lower EAS richness. Historical (1996) levels of Governance and Trade better explained response variables than current (2015) levels. Thus, our results reveal a historical legacy of these two predictors with profound implications for the future of biological invasions. We therefore used Governance and Trade to define a two-dimensional socio-economic space in which the position of a country captures its capacity to address issues of biological invasions. Our results provide novel insights into the complex relationship between socio-ecological predictors and biological invasions. Further, we highlight the need for designing better policies and management measures for alien species, and for integrating biological invasions in global environmental scenarios.

ecology↗

bioRxiv2020

Analysing global economic costs of invasive alien species with the invacost R package

O_LIThe reported costs of invasive alien species from the global database InvaCost are heterogenous and cover different spatio-temporal scales. A standard procedure for aggregating invasive species cost estimates is necessary to ensure the repeatability and comparativeness of studies. C_LIO_LIWe introduce here the invacost R package, an open-source software designed to query and analyse the InvaCost database. We illustrate this package and its framework with cost data associated with invasive alien invertebrates. C_LIO_LIFirst, the invacost package provides updates of this dynamic database directly in the analytical environment R. Second, it helps understand the heteregoneous nature of monetary cost data for invasive species, processes to harmonize the data, and the inherent biases associated with such data. Third, it readily provides complementary methods to investigate the costs of invasive species at different scales, all the while accounting for econometric statistical issues. C_LIO_LIThis tool will be useful for scientists working on invasive alien species, by (i) facilitating access to and use of this multi-disciplinary data resource and (ii) providing a standard procedure which will facilitate reproducibility and comparability among studies, one of the major critics of this topic until now. It should facilitate further interdisciplinary works including economists and invasion ecology researchers. C_LI

ecology↗