Impact of climate change on freshwater snail species' ranges

Global warming is expected to be associated with diverse changes in freshwater habitats in north-western Europe. Increasing evaporation, lower oxygen concentration due to increased water temperature and changes in precipitation pattern are likely to affect the survival ratio and reproduction rate of freshwater gastropods (Pulmonata, Basommatophora). This work is a comprehensive analyse of the climatic factors influencing their ranges both in the past and in the near future. A macroecological approach showed that for a great proportion of genera the ranges were projected to contract by 2080, even if unlimited dispersal was assumed. The forecasted warming in the cooler northern ranges predicted the emergence of new suitable areas, but also reduced drastically the available habitat in the southern part of the studied region. In order to better understand the ranges dynamics in the past and the post glacial colonisation patterns, an approach combining ecological niche modelling and phylogeography was used for two model species, Radix balthica and Ancylus fluviatilis. Phylogeographic model selection on a COI mtDNA dataset confirmed that R. balthica most likely spread from two central European disjunct refuges after the last glacial maximum. The phylogeographic analysis of A. fluviatilis, using 16S and COI mtDNA datasets, also inferred central European refugia. The absence of niche conservatism (adaptive potential) inferred for A. fluviatilis puts a cautionary note on the use of climate envelope models to predict the future ranges of this species. However, the other model species exhibited strong niche conservatism, which allow putting confidence into such predictions. A profound faunal shift will take place in Central Europe within the next century, either permitting the establishment of species currently living south of the studied region or the proliferation of organisms relying on the same food resources. This study points out the need for further investigations on the dispersal modes of freshwaters snails, since the future range size of the species depend on their ability to establish in newly available habitats. Likewise, the mixed mating system of these organisms gives them the possibility to fund a new population from a single individual. It will probably affect the colonisation success and needs further investigation

Comparing the efficacy of morphologic and DNA-based taxonomy in the freshwater gastropod genus Radix (Basommatophora, Pulmonata)

BACKGROUND: Reliable taxonomic identification at the species level is the basis for many biological disciplines. In order to distinguish species, it is necessary that taxonomic characters allow for the separation of individuals into recognisable, homogeneous groups that differ from other such groups in a consistent way. We compared here the suitability and efficacy of traditionally used shell morphology and DNA-based methods to distinguish among species of the freshwater snail genus Radix (Basommatophora, Pulmonata). RESULTS: Morphometric analysis showed that shell shape was unsuitable to define homogeneous, recognisable entities, because the variation was continuous. On the other hand, the Molecularly defined Operational Taxonomic Units (MOTU), inferred from mitochondrial COI sequence variation, proved to be congruent with biological species, inferred from geographic distribution patterns, congruence with nuclear markers and crossing experiments. Moreover, it could be shown that the phenotypically plastic shell variation is mostly determined by the environmental conditions experienced. CONCLUSION: Contrary to DNA-taxonomy, shell morphology was not suitable for delimiting and recognising species in Radix. As the situation encountered here seems to be widespread in invertebrates, we propose DNA-taxonomy as a reliable, comparable, and objective means for species identification in biological research

Mitogenomic phylogeny of bee families confirms the basal position and monophyly of Melittidae

Bees (Anthophila) represent a critical taxon for the ecosystem service of pollination and hence have received great scientific attention. The more than 20,000 known species of bees are grouped in seven families. Yet, the relationships between bee families are not entirely clear, and specifically, the position of Melittidae and their monophyly has been discussed in the past. Here, we present the most comprehensive mitogenomic phylogeny of bees including five members of Melittidae from two sub- families and three tribes. Our results suggest monophyly of the family Melittidae and further support their basal position. The data also support the two subfamilies, but are not in line with current assignment of tribes. Our results show, despite advancement with transcriptomic and whole genomic data, the value of mitochondrial data for the reconstruction of phylogenies

Intraspecific phenotypic variation in life history traits of Daphnia galeata populations in response to fish kairomones

Phenotypic plasticity is the ability of a genotype to produce different phenotypes depending on the environment. It has an influence on the adaptive potential to environmental change and the capability to adapt locally. Adaptation to environmental change happens at the population level, thereby contributing to genotypic and phenotypic variation within a species. Predation is an important ecological factor structuring communities and maintaining species diversity. Prey developed different strategies to reduce their vulnerability to predators by changing their behaviour, their morphology or their life history. Predator-induced life history responses in Daphnia have been investigated for decades, but intra-and inter-population variability was rarely addressed explicitly. We addressed this issue by conducting a common garden experiment with 24 clonal lines of European Daphnia galeata originating from four populations, each represented by six clonal lines. We recorded life history traits in the absence and presence of fish kairomones. Additionally, we looked at the shape of experimental individuals by conducting a geometric morphometric analysis, thus assessing predator-induced morphometric changes. Our data revealed high intraspecific phenotypic variation within and between four D. galeata populations, the potential to locally adapt to a vertebrate predator regime as well as an effect of the fish kairomones on morphology of D. galeata

Traitement social de l'encombrement : prévention et réduction des déchets dans les styles de vie alternatifs

International audienc

Traitement social de l'encombrement : prévention et réduction des déchets dans les styles de vie alternatifs

International audienc

Traitement social de l'encombrement : prévention et réduction des déchets dans les styles de vie alternatifs

International audienc

Intrapopulation variability in a functional trait: Susceptibility ofDaphniato limitation by dietary fatty acids

Functional traits are measurable characteristics of an organism that have an impact on its fitness. Variation in functional traits between and among species has been suggested to represent the basis for competition and selection, thus allowing for evolution in natural populations. In freshwater ecosystems, the availability of essential polyunsaturated fatty acids (PUFAs), in particular omega 3- and omega 6-PUFAs, determines the food quality of phytoplankton for the herbivorous zooplanktonDaphnia, an unselective filter feeder. The content of such essential PUFAs in the phytoplankton is thus a functional phytoplankton trait affecting the trophic transfer efficiency and dynamics at the pelagic plant-herbivore interface. In turn, the susceptibility of consumers to become limited by the availability of essential PUFAs is a fitness-determining trait ofDaphniagenotypes, and variability of this herbivore trait may thus affect the daphnids' intrapopulation competition. To estimate the intrapopulation variation in susceptibility, we isolated clonal lines ofDaphnia longispinafrom a natural population and compared the strength of their limitation by dietary PUFA availability via standardised laboratory growth assays. We used a liposome supplementation technique to enrich a PUFA-poor green alga with essential omega 3- and omega 6-PUFAs and determined juvenile somatic growth rate of differentD. longispinagenotypes as a fitness proxy. As expected,D. longispinagenotypes that coexisted in a natural population differed markedly in their specific patterns of susceptibility to dietary PUFA availability. On average, theD. longispinapopulation was more strongly susceptible to limitations in the availability of the omega 6-PUFA arachidonic acid (20:4 omega 6) than to limitations in the availability of omega 3-PUFAs alpha-linolenic acid (18:3 omega 3) and eicosapentaenoic acid (20:5 omega 3). The ability to cope with PUFA limitation is thus a crucial trait that can probably affect intraspecific competition andDaphniapopulation structure. Therefore, we suggest that such intrapopulation variation in susceptibility to absence of dietary PUFAs might be one of the driving forces of natural selection and local adaptation among freshwater zooplankton

Supporting information File 1

Supplementary file 1: Tables S1-S7 accompanying the publication "Contrasting patterns of divergence at the regulatory and sequence level in European Daphnia galeata natural populations", Suda Parimala Ravindran, Maike Herrmann and Mathilde Cordellier. For the Table of Contents please refer to the README file