Diversity of Chironomidae (Diptera) breeding in the Great Stour, Kent: baseline results from the Westgate Parks non-biting midge project

Chalk rivers and streams are of conservation importance due their ecological diversity, historical relevance and economic value. With more than 200 chalk watercourses, England is considered unusual in having the most chalk rivers in the world. However, due to increasing anthropogenic activities, many English chalk rivers and streams are becoming badly degraded. The non-biting midges or chironomids (Diptera, Chironomidae) are considered key-stone taxa in aquatic food webs, and have been used as ecological indicators of freshwater quality and environmental stress. Here we determined the generic richness, diversity, and community structure of Chironomidae across six sites in the mid-section of the Great Stour in Kent, a chalk river for which concern has been expressed regarding both water and habitat quality. Based on the morphological identification of 1336 insect larvae from the six sites (four in Westgate Parks, Canterbury, and two at nearby locations upstream and downstream from Canterbury City), a total of 20 genera of Chironomidae were identified, including some taxa indicative of freshwater habitats with low levels of organic pollution. There were different levels of generic richness and diversity among sites, and while there was little variation in the community composition among the sites within Westgate Parks, there were noticeable generic differences among Westgate Parks sites compared with those upstream and downstream, showing the highest complementarity and Beta diversity values. Overall, the results were comparable with other studies on chironomids in chalk rivers and other river systems. Although spatially limited to a small stretch of river, this represents the first study on chironomids in the Great Stour and provides baseline information on the diversity and structure of this important insect group with aquatic larvae, useful for the objective interpretation of any future biological assessments and monitoring programmes on the Kentish Stour, and also for comparisons with other chalk rivers

Strong suppression of Coulomb corrections to the cross section of e+e- pair production in ultrarelativistic nuclear collisions

The Coulomb corrections to the cross section of $e^+e^-$ pair production in ultrarelativistic nuclear collisions are calculated in the next-to-leading approximation with respect to the parameter $L=\ln \gamma_A\gamma_B$ ($\gamma_{A,B}$ are the Lorentz factors of colliding nuclei). We found considerable reduction of the Coulomb corrections even for large $\gamma_A\gamma_B$ due to the suppression of the production of $e^+e^-$ pair with the total energy of the order of a few electron masses in the rest frame of one of the nuclei. Our result explains why the deviation from the Born result were not observed in the experiment at SPS.Comment: 4 pages, RevTe

Pervasive genetic associations between traits causing reproductive isolation in Heliconius butterflies

Ecological speciation proceeds through the accumulation of divergent traits that contribute to reproductive isolation, but in the face of gene flow traits that characterize incipient species may become disassociated through recombination. Heliconius butterflies are well known for bright mimetic warning patterns that are also used in mate recognition and cause both pre- and post-mating isolation between divergent taxa. Sympatric sister taxa representing the final stages of speciation, such as Heliconius cydno and Heliconius melpomene, also differ in ecology and hybrid fertility. We examine mate preference and sterility among offspring of crosses between these species and demonstrate the clustering of Mendelian colour pattern loci and behavioural loci that contribute to reproductive isolation. In particular, male preference for red patterns is associated with the locus responsible for the red forewing band. Two further colour pattern loci are associated, respectively, with female mating outcome and hybrid sterility. This genetic architecture in which ‘speciation genes’ are clustered in the genome can facilitate two controversial models of speciation, namely divergence in the face of gene flow and hybrid speciation

Threatened reef corals of the world

10.1371/journal.pone.0034459PLoS ONE73

Biodiversity, Disparity and Evolvability

A key problem in conservation biology is how to measure biological diversity. Taxic diversity (the number of species in a community or in a local biota) is not necessarily the most important aspect, if what most matters is to evaluate how the loss of the different species may impact on the future of the surviving species and communities. Alternative approaches focus on functional diversity (a measure of the distribution of the species among the different 'jobs' in the ecosystem), others on morphological disparity, still others on phylogenetic diversity. There are three major reasons to prioritize the survival of species which provide the largest contributions to the overall phylogenetic diversity. First, evolutionarily isolated lineages are frequently characterized by unique traits. Second, conserving phylogenetically diverse sets of taxa is valuable because it conserves some sort of trait diversity, itself important in so far as it helps maintain ecosystem functioning, although a strict relationships between phylogenetic diversity and functional diversity cannot be taken for granted. Third, in this way we maximize the "evolutionary potential" depending on the evolvability of the survivors. This suggests an approach to conservation problems focussed on evolvability, robustness and phenotypic plasticity of developmental systems in the face of natural selection: in other terms, an approach based on evolutionary developmental biology

Systematics and the Conservation of Biological Diversity

Volume: 83Start Page: 47End Page: 5