Éditeur(s) : HAL CCSD Springer
Résumé : International audience
With the development of genetics methods, it becomes possible to study the population structure and some aspects of the reproductive behaviour of endangered sharks. Here we describe the isolation of 20 polymorphic microsatellite markers in the bull shark Carcharhinus leucas (Carcharhinidae) and their characteristics. Two to 10 alleles per locus were detected. Observed and expected heterozygosities ranged from 0.00 to 0.78 and from 0.05 to0.80, respectively. Four markers showed deviations from Hardy–Weinberg equilibrium; among them, three showed presence of null alleles. No linkage disequilibrium was detected among any of the loci. Moreover, four, 11 and 19 of these 20 markers successfully cross-amplified in the tiger shark Galeocerdo cuvier, the sandbar shark Carcharhinus plumbeus and the dusky shark Carcharhinus obscurus, respectively.
ISSN: 1877-7252

hal-01253773
https://hal.archives-ouvertes.fr/hal-01253773
https://hal.archives-ouvertes.fr/hal-01253773/document
https://hal.archives-ouvertes.fr/hal-01253773/file/Pirog%20et%20al.%20-%202015%20-%20Isolation%20and%20characterization%20of%2020%20microsatellit_hal.pdf
DOI : 10.1007/s12686-014-0308-3

Éditeur(s) : HAL CCSD WILEY-BLACKWELL Wiley
Résumé : International audience
Connectivity among populations determines the dynamics and evolution of populations, and its assessment is essential in ecology in general and in conservation biology in particular. The robust basis of any ecological study is the accurate delimitation of evolutionary units, such as populations, metapopulations and species. Yet a disconnect still persists between the work of taxonomists describing species as working hypotheses and the use of species delimitation by molecular ecologists interested in describing patterns of gene flow. This problem is particularly acute in the marine environment where the inventory of biodiversity is relatively delayed, while for the past two decades, molecular studies have shown a high prevalence of cryptic species. In this study, we illustrate, based on marine case studies, how the failure to recognize boundaries of evolutionary-relevant unit leads to heavily biased estimates of connectivity. We review the conceptual framework within which species delimitation can be formalized as falsifiable hypotheses and show how connectivity studies can feed integrative taxonomic work and vice versa. Finally, we suggest strategies for spatial, temporal and phylogenetic sampling to reduce the probability of inadequately delimiting evolutionary units when engaging in connectivity studies.
ISSN: 0962-1083

hal-01218810
https://hal.archives-ouvertes.fr/hal-01218810
DOI : 10.1111/mec.13048

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Until recently, our ability to implement and assess spatial marine management approaches has been limited by a lack of information regarding processes that bind marine ecosystems, including habitat locations, larval and adult movement, trophic interactions, and fisher behavior. However, recent advances in habitat-mapping technologies, genetics, marine microchemistry, animal tracking and numerical modeling have greatly enhanced our knowledge of these processes. Although these advances have yet to be fully integrated into management decisions, they have the potential to revolutionize spatial marine management. Nevertheless, this revolution will require advances in our ability to share and integrate data into models of marine ecosystems.
ISSN: 1877-3435

hal-00609464
https://hal.archives-ouvertes.fr/hal-00609464
DOI : 10.1016/j.cosust.2010.02.002

Éditeur(s) : HAL CCSD CSIRO Publishing
Résumé : International audience
The present study assessed the occurrence of multiple paternity in four litters of bull shark Carcharhinus leucas (n¼5, 8, 9 and 11 embryos) sampled at Reunion Island in the Western Indian Ocean. Using 21 microsatellite loci, we revealed that two litters were generated from two sires each, demonstrating for the first time multiple paternity for this species. We also reported a high paternal skew (10 : 1 in Litter 1 and 7 : 1 in Litter 3), which may be because of postcopulatory or post-zygotic selection processes. These results contribute to a better understanding of the reproductive behaviour of the bull shark, which remains poorly documented. The present study must be expanded to assess the frequency of multiple paternity in this species, and to test for genetic or cryptic benefits (convenience polyandry), which is important for long-term conservation and management plans.
ISSN: 1323-1650

hal-01253775
https://hal.archives-ouvertes.fr/hal-01253775
https://hal.archives-ouvertes.fr/hal-01253775/document
https://hal.archives-ouvertes.fr/hal-01253775/file/Pirog%20et%20al.%20-%202015%20-%20First%20evidence%20of%20multiple%20paternity%20in%20the%20bull%20s_hal.pdf
DOI : 10.1071/mf15255

Éditeur(s) : HAL CCSD PeerJ
Résumé : International audience
The tiger shark Galeocerdo cuvier (Carcharhinidae) is a large elasmobranch suspected to have, as other apex predators, a keystone function in marine ecosystems and is currently considered Near Threatened (Red list IUCN). Knowledge on its ecology, which is crucial to design proper conservation and management plans, is very scarce. Here we describe the isolation of eight polymorphic microsatellite loci using 454 GS-FLX Titanium pyrosequencing of enriched DNA libraries. Their characteristics were tested on a population of tiger shark (n = 101) from Reunion Island (SouthWestern Indian Ocean). All loci were polymorphic with a number of alleles ranging from two to eight. No null alleles were detected and no linkage disequilibrium was detected after Bonferroni correction. Observed and expected heterozygosities ranged from 0.03 to 0.76 and from 0.03 to 0.77, respectively. No locus deviated from Hardy-Weinberg equilibrium and the global F IS of the population was of 0.04 NS. Some of the eight loci developed here successfully cross-amplified in the bull shark Carcharhinus leucas (one locus), the spinner shark Carcharhinus brevipinna (four loci), the sandbar shark Carcharhinus plumbeus (five loci) and the scalloped hammerhead shark Sphyrna lewini (two loci). We also designed primers to amplify and sequence a mitochondrial marker, the control region. We sequenced 862 bp and found a low genetic diversity, with four polymorphic sites, a haplotype diversity of 0.15 and a nucleotide diversity of 2 × 10 −4 .
ISSN: 2167-8359

hal-01317961
https://hal.archives-ouvertes.fr/hal-01317961
https://hal.archives-ouvertes.fr/hal-01317961/document
https://hal.archives-ouvertes.fr/hal-01317961/file/Pirog_2016PeerJ_microsat_tiger_shark.pdf
DOI : 10.7717/peerj.2041