Effective population size and heterozygosity-fitness correlations in a population of the Mediterranean lagoon ecotype of long-snouted seahorse Hippocampus guttulatus

Type Article
Date 2019-12
Language English
Author(s) Riquet Florentine1, Lieutard-Haag Cathy1, Serluca Giulia1, Woodall Lucy2, 3, Claude Julien1, Louisy Patrick4, 5, Bierne NicolasORCID1
Affiliation(s) 1 : ISEM, Univ Montpellier, CNRS, EPHE, IRD, Montpellier, France
2 : Department of Zoology, University of Oxford, John Krebs Field Station, Wytham OX2 8QJ, UK
3 : Natural History Museum, Cromwell Road, London SW7 5BD, UK
4 : ECOMERS Laboratory, Faculty of Sciences, University of Nice Sophia Antipolis, Parc Valrose, Nice, France
5 : Association Peau-Bleue, 46 Rue des Escais, Agde, France
Source Conservation Genetics (1566-0621) (Springer), 2019-12 , Vol. 20 , N. 6 , P. 1281-1288
DOI 10.1007/s10592-019-01210-3
WOS© Times Cited 5
Keyword(s) Marine endangered species, Hippocampus guttulatus, Population effective size, Inbreeding, Heterozygosity-fitness correlations

The management of endangered species is complicated in the marine environment owing to difficulties to directly access, track and monitor in situ. Population genetics provide a genuine alternative to estimate population size and inbreeding using non-lethal procedures. The long-snouted seahorse, Hippocampus guttulatus, is facing multiple threats such as human disturbance or by-catch, and has been listed in the red list of IUCN. One large population is found in the Thau lagoon, in the south of France. A recent study has shown this population belongs to a genetic lineage only found in Mediterranean lagoons that can be considered as an Evolutionarily Significant Unit (ESU) and should be managed with dedicated conservation strategies. In the present study, we used genetic analysis of temporal samples to estimate the effective population size of the Thau population and correlations between individual multilocus heterozygosity and fitness traits to investigate the possible expression of inbreeding depression in the wild. Non-invasive sampling of 172 seahorses for which profiles were pictured and biometric data recorded were genotyped using 291 informative SNPs. Genetic diversity remained stable over a 7-year time interval. In addition, very low levels of close relatedness and inbreeding were observed, with only a single pair of related individuals in 2008 and two inbreds in 2013. We did not detect departure from identity equilibrium. The effective population size was estimated to be N-e = 2742 ( 40 reproductive seahorses per km(2)), larger than previously thought. No correlation was observed between heterozygosity and fluctuating asymmetry or other morphometric traits, suggesting a population with low variance in inbreeding. Together these results suggest this population does not meet conventional genetic criteria of an endangered population, as the population seems sufficiently large to avoid inbreeding and its detrimental effects. This study paves the way for the genetic monitoring of this recently discovered ESU of a species with patrimonial and conservation concerns.

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Riquet Florentine, Lieutard-Haag Cathy, Serluca Giulia, Woodall Lucy, Claude Julien, Louisy Patrick, Bierne Nicolas (2019). Effective population size and heterozygosity-fitness correlations in a population of the Mediterranean lagoon ecotype of long-snouted seahorse Hippocampus guttulatus. Conservation Genetics, 20(6), 1281-1288. Publisher's official version : https://doi.org/10.1007/s10592-019-01210-3 , Open Access version : https://archimer.ifremer.fr/doc/00797/90923/