Phenology of marine turtle nesting revealed by statistical model of the nesting season

BACKGROUND: Marine turtles deposit their eggs on tropical or subtropical beaches during discrete nesting seasons that span several months. The number and distribution of nests laid during a nesting season provide vital information on various aspects of marine turtle ecology and conservation. RESULTS: In the case of leatherback sea turtles nesting in French Guiana, we developed a mathematical model to explore the phenology of their nesting season, derived from an incomplete nest count dataset. We detected 3 primary components in the nest distribution of leatherbacks: an overall shape that corresponds to the arrival and departure of leatherback females in the Guianas region, a sinusoidal pattern with a period of approximately 10 days that is related to physiological constraints of nesting female leatherbacks, and a sinusoidal pattern with a period of approximately 15 days that likely reflects the influence of spring high tides on nesting female turtles. CONCLUSION: The model proposed here offers a variety of uses for both marine turtles and also other taxa when individuals are observed in a particular location for only part of the year

Rarity Value and Species Extinction: The Anthropogenic Allee Effect

Standard economic theory predicts that exploitation alone is unlikely to result in species extinction because of the escalating costs of finding the last individuals of a declining species. We argue that the human predisposition to place exaggerated value on rarity fuels disproportionate exploitation of rare species, rendering them even rarer and thus more desirable, ultimately leading them into an extinction vortex. Here we present a simple mathematical model and various empirical examples to show how the value attributed to rarity in some human activities could precipitate the extinction of rare species—a concept that we term the anthropogenic Allee effect. The alarming finding that human perception of rarity can precipitate species extinction has serious implications for the conservation of species that are rare or that may become so, be they charismatic and emblematic or simply likely to become fashionable for certain activities

Early acute microvascular kidney transplant rejection in the absence of anti-HLA antibodies is associated with preformed IgG antibodies against diverse glomerular endothelial cell antigens

International audienceBACKGROUND: Although anti-HLA antibodies (Abs) cause most antibody-mediated rejections of renal allografts, non-anti-HLA Abs have also been postulated to contribute. A better understanding of such Abs in rejection is needed.METHODS: We conducted a nationwide study to identify kidney transplant recipients without anti-HLA donor-specific Abs who experienced acute graft dysfunction within 3 months after transplantation and showed evidence of microvascular injury, called acute microvascular rejection (AMVR). We developed a crossmatch assay to assess serum reactivity to human microvascular endothelial cells, and used a combination of transcriptomic and proteomic approaches to identify non-HLA Abs.RESULTS: We identified a highly selected cohort of 38 patients with early acute AMVR. Biopsy specimens revealed intense microvascular inflammation and the presence of vasculitis (in 60.5%), interstitial hemorrhages (31.6%), or thrombotic microangiopathy (15.8%). Serum samples collected at the time of transplant showed that previously proposed anti-endothelial cell Abs-angiotensin type 1 receptor (AT1R), endothelin-1 type A and natural polyreactive Abs-did not increase significantly among patients with AMVR compared with a control group of stable kidney transplant recipients. However, 26% of the tested AMVR samples were positive for AT1R Abs when a threshold of 10 IU/ml was used. The crossmatch assay identified a common IgG response that was specifically directed against constitutively expressed antigens of microvascular glomerular cells in patients with AMVR. Transcriptomic and proteomic analyses identified new targets of non-HLA Abs, with little redundancy among individuals.CONCLUSIONS: Our findings indicate that preformed IgG Abs targeting non-HLA antigens expressed on glomerular endothelial cells are associated with early AMVR, and that cell-based assays are needed to improve risk assessments before transplant

Contacts et acculturations en Méditerranée occidentale

La question des contacts entre les différents peuples qui bordent les rives de la Méditerranée nord occidentale est l’un des sujets phares de la recherche archéologique de ces trente dernières années. Que l’on parle d’époque archaïque et classique ou de Protohistoire et d’âge du Fer, les échanges et les processus d’acculturation de ces peuples qui entrèrent alors en contact les uns avec les autres : Grecs, Celtes, Phéniciens, Ibères, Ligures, Étrusques, ont retenu l’attention des chercheurs travaillant sur l’expansion grecque dans ces régions, sur les trafics commerciaux, sur les échanges culturels. L’œuvre de Michel Bats (Directeur de recherche honoraire du CNRS) traverse toutes ces thématiques : la présence des Phocéens et des Étrusques dans le bassin occidental de la Méditerranée, l’acculturation et les identités ethno-culturelles, les recherches sur la céramique et ses usages dans une perspective anthropologique, l’appropriation de l’écriture par les sociétés protohistoriques. Ses collègues et amis, en organisant ce colloque et en participant à ces actes, entendent lui témoigner leur amitié et leur dette intellectuelle. Ce volume réunit des articles des meilleurs spécialistes, actuels de la question - des chercheurs de toute la Méditerranée - autour des quatre grands thèmes que nous venons d’évoquer afin tout à la fois de dresser un bilan et de définir de nouvelles perspectives. Cet ouvrage présente donc aussi bien des synthèses - sur la présence grecque en Espagne, sur l’origine de l’écriture, sur les pratiques funéraires, sur les identités culturelles et ethniques - que des découvertes récentes concernant la thématique des contacts et de l’acculturation en Méditerranée nord occidentale : l’agglomération du Premier âge du Fer de La Cougourlude (Lattes, Hérault) fouillée durant l’été 2010 ; le sanctuaire hellénistique de Cumes et les fouilles récentes de Fratte en Italie ; les ateliers de potiers de Rosas en Espagne ; les dernières découvertes d’Olbia de Provence

La dynamique des populations de tortues luths de Guyane française (recherche des facteurs impliqués et application à la mise en place de stratégies de conservation)

La connaissance de la dynamique d'une population est un préliminaire indispensable à la mise en place de stratégies de conservation raisonnées. Dans le cas de la tortue luth (Dermochelys coriacea), la connaissance de la dynamique des populations est encore très fragmentaire en raison de la difficulté d'accès aux individus, tant sur le plan spatial que temporel. Or, face à la chute des effectifs de femelles sur de nombreux sites de pontes du Pacifique, la mise en place de mesure de conservation semble urgente. Nous avons donc étudié les facteurs impliqués dans la dynamique des populations des tortues luths femelles qui pondent dans la région guyano-surinamienne.Nos résultats suggèrent que le nombre de nids est un estimateur biaisé de l'abondance des femelles. En effet, depuis les années 1970, le nombre de femelles augmente plus fortement que le nombre de pontes. Cette différence pourraient s'expliquer par une diminution de l'investissement reproducteur liée aux variations climatiques sur cette même période. Nos résultats confirment que le stade adulte est le stade sur lequel les mesures de conservation doivent se concentrer. Cependant, alors que les captures accidentelles liées à la pêche sur le littoral guyano-surinamien sont supposées être la menace majeure pour la population, les projections matricielles montrent qu'elle semble y être relativement résistante. Néanmoins, la fragilité avérée de certaines populations pacifiques tend à proposer de rester extrêmement vigilant sur le respect de la règlementation de la pêche dans la région.Adequate knowledge of population dynamics is the first step in establishing a successful conservation strategy. In the case of leatherback sea turtle (Dermochelys coriacea), information on population dynamics is patchy because of the limited assess to individuals, either spatially or temporally. Nevertheless, in the face of the decline in several nesting populations in the Pacific Ocean, the initiation of management policies is urgent. Therefore, I focused my studies on elucidating the main parameters that drive population dynamic of female leatherbacks nesting in French Guiana and Suriname.The results of this work suggest that the number of nests, classically used as an index of population size in sea turtle research, is a biased estimator of female abundance. Indeed, since 1970, the number of females has increased faster that the number of nests. This difference is due to the diminution of reproductive investment related to the climatic variations during this period. Our results confirm that conservation policies should focus on adult survival rate. However, whereas the accidental capture of turtles by fisheries on the French Guiana coast appears to be the major threat for the population, the matrix projections reveal that the population is apparently relatively resistant to this pressure. Nevertheless, the demonstrated sensitivity of some leatherback populations in the Pacific Ocean with respect to accidental capture suggests that fishing regulations to reduce accidental capture in the French Guiana and Suriname region are a necessary component to maintaining the leatherback nesting population.ORSAY-PARIS 11-BU Sciences (914712101) / SudocSudocFranceF

Estimating clutch frequency in the sea turtle Dermochelys coriacea using stopover duration

International audienc

Trade-off between current reproductive effort and delay to next reproduction in the leatherback sea turtle

International audienceThe trade-off between current and future reproduction plays an important role in demographic analyses. This can be revealed by the relationship between the number of years without reproduction and reproductive investment within a reproductive year. However, estimating both the duration between two successive breeding season and reproductive effort is often limited by variable recapture or resighting effort. Moreover, a supplementary difficulty is raised when nonbreeder individuals are not present sampling breeding grounds, and are therefore unobservable. We used capture-recapture (CR) models to investigate intermittent breeding and reproductive effort to test a putative physiological trade-off in a long-lived species with intermittent breeding, the leatherback sea turtle. We used CR data collected on breeding females on Awa:la-Ya:lima:po beach (French Guiana, South America) from 1995 to 2002. By adding specific constraints in multistate (MS) CR models incorporating several non-observable states, we modelled the breeding cycle in leatherbacks and then estimated the reproductive effort according to the number of years elapsed since the last nesting season. Using this MS CR framework, the mean survival rate was estimated to 0.91 and the average resighting probability to 0.58 (ranged from 0.30 to 0.99). The breeding cycle was found to be limited to 3 years. These results therefore suggested that animals whose observed breeding intervals are greater than 3 years were most likely animals that escaped detection during their previous nesting season(s). CR data collected in 2001 and 2002 allowed us to compare the individual reproductive effort between females that skipped one breeding season and females that skipped two breeding seasons. These inferences led us to conclude that a trade-off between current and future reproduction exists in leatherbacks nesting in French Guiana, likely linked to the resource provisioning required to invest in reproduction