Cryptic species and genetic connectivity among populations of the coral Pocillopora damicornis (Scleractinia) in the tro
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ORIGINAL PAPER
Cryptic species and genetic connectivity among populations of the coral Pocillopora damicornis (Scleractinia) in the tropical southwestern Pacific Nicolas Oury1,2 · Pauline Gélin1,3 · Hélène Magalon1,2,3 Received: 19 March 2020 / Accepted: 19 August 2020 © Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract Studying population genetic connectivity (i.e., identifying gene flow among populations and understanding their impacts on the genetic structure and diversity of populations) is first a matter of knowing what we work on, that is, accurately delimiting evolutionary units. Here, we focused on Pocillopora damicornis sensu stricto (or Pocillopora PSH04 sensu Gélin et al. in Mol Phylogenet Evol 109:430–446. http://dx.doi.org/10.1016/j.ympev.2017.01.018, 2017). From 458 colonies sampled within the tropical southwestern Pacific [Chesterfield Islands and New Caledonia (Grande Terre and Loyalty Islands)], Bayesian assignments and network analyses were conducted with 11-microsatellite loci to first evaluate the genetic partitioning of the colonies in distinct Secondary Species Hypotheses (SSHs), then in distinct clusters. Population genetic connectivity was then assessed for each cluster separately. Pocillopora PSH04 was partitioned into two highly differentiated SSHs (SSH04a and SSH04b), regularly found in sympatry. Furthermore, SSH04a was subdivided into two clusters (SSH04a-1 and SSH04a-2). This pattern of genetic structuring seems not related to clonality, but rather to the establishment of reproductive barriers. Nevertheless, considering each cluster separately, the populations appeared highly differentiated, suggesting relatively weak gene flow. This low connectivity among populations, coupled with the existence of cryptic species, brings new insights to the connectivity pattern of this understudied Pacific region.
Introduction Population connectivity (i.e., the process linking habitats and populations geographically separated) is a powerful force that maintains the genetic cohesion of a species over its distribution range, via the homogenisation of genetic variations
Responsible Editor: O. Puebla. Reviewed by undisclosed experts. Electronic supplementary material The online version of this article (https://doi.org/10.1007/s00227-020-03757-z) contains supplementary material, which is available to authorized users. * Nicolas Oury [email protected] 1
UMR ENTROPIE (Université de La Réunion, IRD, IFREMER, Université de Nouvelle-Calédonie, CNRS), Université de La Réunion, St Denis, La Réunion, France
2
Laboratoire Cogitamus, Paris, France
3
Laboratoire d’Excellence CORAIL, Perpignan, France
among its populations (Mayr 1963). In marine environments, population connectivity occurs through exchanges of individuals or propagules (e.g., gametes, eggs, or larvae), synonym of a transfer of alleles (effective dispersal; Cowen et al. 2003; Cowen and Sponaugle 2009). Population genetic connectivity, therefore, represents a key element of population dynamics, genetic st
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