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Auteur (up) Pirog, A.; Jaquemet, S.; Soria, M.; Magalon, H.
Titre First evidence of multiple paternity in the bull shark (Carcharhinus leucas) Type Article scientifique
Année 2017 Publication Revue Abrégée Mar. Freshw. Res.
Volume 68 Numéro 1 Pages 195-201
Mots-Clés brown smoothhound shark; convenience polyandry; genetic benefits; hammerhead shark; mating-behavior; microsatellite; microsatellite null alleles; mustelus-henlei; paternity test; polyandry; population sizes; triaenodon-obesus; whitetip reef shark
Résumé The present study assessed the occurrence of multiple paternity in four litters of bull shark Carcharhinus leucas (n = 5, 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 post-copulatory 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.
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ISSN 1323-1650 ISBN Médium
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Numéro d'Appel MARBEC @ alain.herve @ collection 2073
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Auteur (up) Reichel, K.; Masson, J.-P.; Malrieu, F.; Arnaud-Haond, S.; Stoeckel, S.
Titre Rare sex or out of reach equilibrium? The dynamics of F-IS in partially clonal organisms Type Article scientifique
Année 2016 Publication Revue Abrégée BMC Genet.
Volume 17 Numéro Pages 76
Mots-Clés consequences; diversity; evolution; genetic diversity; genetic-structure; Heterozygote excess; hybridization; Inbreeding coefficient; loci; Mating system; microsatellite primers; mutation; Parthenogenesis; Partial asexuality; population-genetics; reproduction
Résumé Background: Partially clonal organisms are very common in nature, yet the influence of partial asexuality on the temporal dynamics of genetic diversity remains poorly understood. Mathematical models accounting for clonality predict deviations only for extremely rare sex and only towards mean inbreeding coefficient (F-IS) over bar < 0. Yet in partially clonal species, both F-IS < 0 and F-IS > 0 are frequently observed also in populations where there is evidence for a significant amount of sexual reproduction. Here, we studied the joint effects of partial clonality, mutation and genetic drift with a state-and-time discrete Markov chain model to describe the dynamics of F-IS over time under increasing rates of clonality. Results: Results of the mathematical model and simulations show that partial clonality slows down the asymptotic convergence to F-IS = 0. Thus, although clonality alone does not lead to departures from Hardy-Weinberg expectations once reached the final equilibrium state, both negative and positive F-IS values can arise transiently even at intermediate rates of clonality. More importantly, such “transient” departures from Hardy Weinberg proportions may last long as clonality tunes up the temporal variation of F-IS and reduces its rate of change over time, leading to a hyperbolic increase of the maximal time needed to reach the final mean (F-IS,F-infinity) over bar value expected at equilibrium. Conclusion: Our results argue for a dynamical interpretation of F-IS in clonal populations. Negative values cannot be interpreted as unequivocal evidence for extremely scarce sex but also as intermediate rates of clonality in finite populations. Complementary observations (e.g. frequency distribution of multiloci genotypes, population history) or time series data may help to discriminate between different possible conclusions on the extent of clonality when mean (F-IS) over bar values deviating from zero and/or a large variation of F-IS over loci are observed.
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Langue English Langue du Résumé Titre Original
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Volume de collection Numéro de collection Edition
ISSN 1471-2156 ISBN Médium
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Numéro d'Appel MARBEC @ alain.herve @ collection 1648
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Auteur (up) Viricel, A.; Simon-Bouhet, B.; Ceyrac, L.; Dulau-Drouot, V.; Berggren, P.; Amir, O.A.; Jiddawi, N.S.; Mongin, P.; Kiszka, J.J.
Titre Habitat availability and geographic isolation as potential drivers of population structure in an oceanic dolphin in the Southwest Indian Ocean Type Article scientifique
Année 2016 Publication Revue Abrégée Mar. Biol.
Volume 163 Numéro 10 Pages 219
Mots-Clés biologically meaningful; bottle-nosed dolphins; genetic differentiation; marine populations; megaptera-novaeangliae; microsatellite loci; mozambique channel; spinner dolphins; stenella-longirostris; tursiops-truncatus
Résumé Delphinid populations show highly variable patterns of genetic diversity and population structure. Previous studies indicate that habitat discontinuities and geographic isolation are major drivers of population division in cetaceans. Spinner dolphins (Stenella longirostris) are distributed in all tropical oceans, but they are particularly common around islands and atolls. This species occurs in shallow waters at daytime to rest and socialise, and feeds on offshore mesopelagic prey overnight. Here, we investigated the genetic population structure of spinner dolphins in the Southwest Indian Ocean along a west-east geographic gradient, from eastern Africa to the Mascarene archipelago. We combined analyses of 12 microsatellite loci, mtDNA control region sequences, and sighting data to assess genetic differentiation and characterise habitat preferences of these populations. Significant genetic structure among the three sampled sites (Zanzibar, Mayotte and La Reunion) was observed using both types of molecular markers. Overall, our results indicate that geographic isolation and potentially other factors, such as shallow-water habitats to rest and socialise, may be important drivers of the genetic population structure of insular spinner dolphins in this region.
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Volume de collection Numéro de collection Edition
ISSN 0025-3162 ISBN Médium
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Numéro d'Appel MARBEC @ alain.herve @ collection 1700
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