BackgroundGeographic variation in the thermal environment impacts a broad range of biochemical and physiological processes and can be a major selective force leading to local population adaptation. In the intertidal copepod Tigriopus californicus, populations along the coast of California show differences in thermal tolerance that are consistent with adaptation, i.e., southern populations withstand thermal stresses that are lethal to northern populations. To understand the genetic basis of these physiological differences, we use an RNA-seq approach to compare genome-wide patterns of gene expression in two populations known to differ in thermal tolerance.ResultsObserved differences in gene expression between the southern (San Diego) and the northern (Santa Cruz) populations included both the number of affected loci as well as the identity of these loci. However, the most pronounced differences concerned the amplitude of up-regulation of genes producing heat shock proteins (Hsps) and genes involved in ubiquitination and proteolysis. Among the hsp genes, orthologous pairs show markedly different thermal responses as the amplitude of hsp response was greatly elevated in the San Diego population, most notably in members of the hsp70 gene family. There was no evidence of accelerated evolution at the sequence level for hsp genes. Among other sets of genes, cuticle genes were up-regulated in SD but down-regulated in SC, and mitochondrial genes were down-regulated in both populations.ConclusionsMarked changes in gene expression were observed in response to acute sub-lethal thermal stress in the copepod T. californicus. Although some qualitative differences were observed between populations, the most pronounced differences involved the magnitude of induction of numerous hsp and ubiquitin genes. These differences in gene expression suggest that evolutionary divergence in the regulatory pathway(s) involved in acute temperature stress may offer at least a partial explanation of population differences in thermal tolerance observed in Tigriopus.

SummaryCompanies are called by institutional organizations to assess their impacts on biodiversity and to take actions to achieve collectively conservation objectives. This paper presents a method to assess whether the pressures exerted by a business and its value chain on biodiversity are compatible with biodiversity conservation. The absolute environmental sustainability assessment framework is used to compare relevant life cycle assessment midpoint and endpoint indicators to the ecological budgets assigned to the company. This approach is illustrated based on the case study of a mass-market retailer with a focus on the pressures exerted by its food portfolio at the agricultural production step. The results indicate that several pressures driving biodiversity loss are not sustainable. The study also highlights the prominent weight of a few product categories in the ecological burden. These findings have implications for mass-market retailers as well as their food value chains and open research perspectives to make such an approach fully operational.

SummaryCorporate social responsibility (CSR) is receiving an increased attention in biodiversity policy. This exploratory study analyses biodiversity-oriented corporate practices and stakeholders' involvement in their implementation based on a content analysis of 34 business commitment plans endorsed as contributions to the French National Biodiversity Strategy and Action Plan (NBSAP). A trans-sectoral typology of practices emerged from this analysis. This typology categorizes, on one hand, CSR practices that directly mitigate biodiversity loss, and on the other hand, procedural activities supporting a better integration of biodiversity issues. External stakeholders were found to be involved in more than two thirds of the CSR actions and played different roles depending if they belonged to the territorial system, the value chain or the institutional system the company. The article concludes with a number of implications for policy-makers as well as business managers and opens research avenues.

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Vers une évaluation absolue de la durabilité écologique : quelle variabilité des valeurs de référence associées à l'écotoxicité aquatique ? 12 Vers une évaluation absolue de la durabilité écologique : quelle variabilité des valeurs de référence associées à l'écotoxicité aquatique ?