Éditeur(s) : HAL CCSD
Résumé : International audience
BACKGROUND: Africa faces a number of unique environmental challenges. Unfortunately, it lacks the infrastructure needed to support the comprehensive environmental studies that could provide the scientific basis to inform environmental policies. There are a number of known sources of endocrine-disrupting chemicals (EDCs) and other hazardous chemicals in Africa. However, a coordinated approach to identify and monitor these contaminants and to develop strategies for public health interventions has not yet been made. OBJECTIVES: This commentary summarizes the scientific evidence presented by experts at the First African Endocrine Disruptors meeting. We describe a "call to action" to utilize the available scientific knowledge to address the impact of EDCs on human and wildlife health in Africa. DISCUSSION: We identify existing knowledge gaps about exposures to EDCs in Africa and describe how well-designed research strategies are needed to address these gaps. A lack of resources for research and a lag in policy implementation slows down intervention strategies and poses a challenge to advancing future health in Africa. CONCLUSION: To address the many challenges posed by EDCs, we argue that Africans should take the lead in prioritization and evaluation of environmental hazards, including EDCs. We recommend the institution of education and training programs for chemical users, adoption of the precautionary principle, establishment of biomonitoring programs, and funding of community-based epidemiology and wildlife research programs led and funded by African institutes and private companies. https://doi.org/10.1289/EHP1774.
Environmental Health Perspectives

hal-01616487
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01616487
DOI : 10.1289/EHP1774
PUBMED : 28935616

Éditeur(s) : HAL CCSD Wiley
Résumé : International audience
AimThe global biodiversity crisis requires the identification of regions with high evolutionary potential, i.e. evolutionary hotspots (evospots). We created an analytical framework based on comparative phylogeography and coalescent methods to assess the dynamics of diversification and population persistence in the reef ecosystem of a little-studied region: the Southwestern Indian Ocean (SWIO).LocationCoral reefs of the SWIO, with comparative data from the Pacific Ocean.MethodsWe generated sequences of mitochondrial DNA (COI and 16S) for 10 widespread brittle-stars (345 specimens) from 21 localities (8 in the SWIO). We analysed them by combining comparative phylogeography approaches, coalescent-based methods, molecular clocks and the concept of evolutionarily significant units (ESUs) to draw conclusions about the drivers of biodiversity in the region.ResultsCryptic diversity was prevalent, increasing lineage diversity within the 10 nominal species by 70% within the SWIO and by 200% across the Indo-West Pacific. All seven new SWIO lineages meet the criteria for ESUs and at least six are biological species. We detected likely intraregional diversifications dating to the Plio-Pleistocene, supporting the SWIO as a generator of biodiversity. Geographical restriction of ESUs, long coalescent times (> 80 ka) and old in situ diversification (> 1 Ma) point to the persistence of populations over multiple glacio-eustatic cycles. We provide data suggesting demographic expansion during sea-level high stands. Regional connectivity was lower, and cryptic differentiation higher in lecithotrophs than in planktotrophs.Main conclusionsThe analytical framework based on a biodiversity survey makes it possible to identify evospots by assessing the potential of a region to maintain and generate biodiversity and by evaluating the evolutionary processes and potential drivers at play.
ISSN: 0305-0270

hal-01369697
http://hal.univ-reunion.fr/hal-01369697
DOI : 10.1111/jbi.12155

Éditeur(s) : HAL CCSD Magnolia Press
Résumé : International audience
Despite their importance in marine biodiversity, invertebrates are far less studied than vertebrates. Given the current globalbiodiversity crisis and insufficient taxonomic resources, sustained efforts need to be undertaken to assess species diversity,especially in the highly threatened ‘biodiversity hotspots’. Réunion is a young volcanic island lying in the Mascarene Islands(south-western Indian Ocean, SWIO), a marine biodiversity hotspot. A substantial sampling effort was conductedaround Réunion Island to document shallow water reef-associated ophiuroid (brittle-stars) diversity, a class recognised asthe most diverse among echinoderms. A total of 33 species were documented, increasing the known species richness ofthe island by 56%. Findings include 15 new records for Réunion, 11 for the Mascarene Islands and 8 for the Indian Ocean.The most diverse family was Ophiocomidae, a family of large, abundant and conspicuous tropical species. Even in thiswell studied family, a new species was revealed by this survey. Morphological variants together with DNA sequence variationswithin several species revealed cryptic species. We compared our results with the known fauna of other MascareneIslands and discuss biogeographic implications for the region.
ISSN: 1175-5326

hal-01327053
https://hal-univ-perp.archives-ouvertes.fr/hal-01327053
DOI : 10.11646/zootaxa.4098.2.4

Éditeur(s) : HAL CCSD Frontiers Media
Résumé : The disease, Heartwater, caused by the Anaplasmataceae E. ruminantium, represents a major problem for tropical livestock and wild ruminants. Up to now, no effective vaccine has been available due to a limited cross protection of vaccinal strains on field strains and a high genetic diversity of Ehrlichia ruminantium within geographical locations. To address this issue, we inferred the genetic diversity and population structure of 194 E. ruminantium isolates circulating worldwide using Multilocus Sequence Typing based on lipA, lipB, secY, sodB, and sucA genes. Phylogenetic trees and networks were generated using BEAST and SplitsTree, respectively, and recombination between the different genetic groups was tested using the PHI test for recombination. Our study reveals the repeated occurrence of recombination between E. ruminantium strains, suggesting that it may occur frequently in the genome and has likely played an important role in the maintenance of genetic diversity and the evolution of E. ruminantium. Despite the unclear phylogeny and phylogeography, E. ruminantium isolates are clustered into two main groups: Group 1 (West Africa) and a Group 2 (worldwide) which is represented by West, East, and Southern Africa, Indian Ocean, and Caribbean strains. Some sequence types are common between West Africa and Caribbean and between Southern Africa and Indian Ocean strains. These common sequence types highlight two main introduction events due to the movement of cattle: from West Africa to Caribbean and from Southern Africa to the Indian Ocean islands. Due to the long branch lengths between Group 1 and Group 2, and the propensity for recombination between these groups, it seems that the West African clusters of Subgroup 2 arrived there more recently than the original divergence of the two groups, possibly with the original waves of domesticated ruminants that spread across the African continent several thousand years ago.
ISSN: 2235-2988

hal-01594501
https://hal.archives-ouvertes.fr/hal-01594501
https://hal.archives-ouvertes.fr/hal-01594501/document
https://hal.archives-ouvertes.fr/hal-01594501/file/paper_MLST_ER_2016_%7B51027B58-C2C7-41C8-9746-BD8A9F387C87%7D.pdf
DOI : 10.3389/fcimb.2016.00111

Éditeur(s) : HAL CCSD BioMed Central
Résumé : [b]Background[/b]: [i]Amblyomma variegatum[/i] and [i]A. hebraeum[/i] are two ticks of veterinary and human health importance in south-east Africa. In Zimbabwe they occupy parapatric (marginally overlapping and juxtaposed) distributions. Understanding the mechanisms behind this parapatry is essential for predicting the spatio-temporal dynamics of Amblyomma spp. and the impacts of associated diseases. It has been hypothesized that exclusive competition between these species results from competition at the levels of male signal reception (attraction-aggregation-attachment pheromones) or sexual competition for mates. This hypothesis predicts that the parapatry described in Zimbabwe could also be present in other countries in the region. [br/][b]Methods[/b]: To explore this competitive exclusion hypothesis we conducted field surveys at the two species' range limits in Mozambique to identify areas of sympatry (overlapping areas) and to study potential interactions (communicative and reproductive interference effects) in those areas. At sympatric sites, hetero-specific mating pairs were collected and inter-specific attractiveness/repellent effects acting at long and short distances were assessed by analyzing species co-occurrences on co-infested herds and co-infested hosts.[br/] [b]Results[/b]: Co-occurrences of both species at sampling sites were infrequent and localized in areas where both tick and host densities were low. At sympatric sites, high percentages of individuals of both species shared attachment sites on hosts and inter-specific mating rates were high. Although cross-mating rates were not significantly different for[i] A. variegatum[/i] and [i]A. hebraeum[/i] females, attraction towards hetero-specific males was greater for [i]A. hebraeum[/i] females than for A. variegatum females and we observed small asymmetrical repellent effects between males at attachment sites.[br/][b]Conclusions[/b]: Our observations suggest near-symmetrical reproductive interference between [i]A. variegatum[/i] and [i]A. hebraeum[/i], despite between-species differences in the strength of reproductive isolation barriers acting at the aggregation, fixation and partner contact levels. Theoretical models predict that sexual competition coupled with hybrid inviability, greatly reduces the probability of one species becoming established in an otherwise suitable location when the other species is already established. This mechanism can explain why the parapatric boundary in Mozambique has formed within an area of low tick densities and relatively infrequent host-mediated dispersal events.
ISSN: 1756-3305

hal-01220744
https://hal.archives-ouvertes.fr/hal-01220744
https://hal.archives-ouvertes.fr/hal-01220744/document
https://hal.archives-ouvertes.fr/hal-01220744/file/2015%20Bournez%20Parasites%20%26%20Vectors_%7B365AAFF5-7041-480B-9B77-9CD0485A9B72%7D.pdf
DOI : 10.1186/s13071-015-1116-7