Éditeur(s) : HAL CCSD Cambridge University Press
Résumé : International audience
Genetic variation was examined in two complex cases of Indo-Pacific pygmy angelfishes (genus Centropyge; Pomacanthidae). The lemonpeel pygmy angelfish C. flavissima (Cuvier and Valenciennes) has a geographically disjunct Indian vs. Pacific distribution and the individuals from these two regions differ by their colour patterns. Previous research on C. flavissima has shown mitochondrial introgression from two related species, C. eibli in the eastern Indian Ocean and C. vrolikii in the Pacific Ocean. Using the 16S rDNA and the CO1 gene as phylogeographic markers, we found no mitochondrial haplotypes in common between Indian Ocean C. flavissima and C. eibli, confirming partial genetic isolation, albeit recent. Also, we found substantial genetic differences between Indian and Pacific C. flavissima populations at the nuclear ETS-2 intron locus. The Indian Ocean form of C. flavissima, thus geographically isolated by >2000 km distance from its Pacific Ocean counterpart, is described as a new species, Centropyge cocosensis sp. nov. Centropyge cocosensis sp. nov. differs in appearance from C. flavissima in having a conspicuous blue iris and a fainter, bluish eye ring. We also found that the yellow pygmy angelfish C. heraldi Woods and Schultz consists of two genetically distinct entities, one distributed widely in the northern tropical Indo-West Pacific, the other distributed in the southern Pacific Ocean. The name originally given to the blackfin pygmy angelfish, C. woodheadi Kuiter, is here resurrected to designate the latter.
EISSN: 1755-2672

hal-01340521
https://hal-univ-perp.archives-ouvertes.fr/hal-01340521
DOI : 10.1007/s12526-016-0509-y

Éditeur(s) : Public Library Science
Résumé : Background: Reconstructing the history of divergence and gene flow between closely-related organisms has long been a difficult task of evolutionary genetics. Recently, new approaches based on the coalescence theory have been developed to test the existence of gene flow during the process of divergence. The deep sea is a motivating place to apply these new approaches. Differentiation by adaptation can be driven by the heterogeneity of the hydrothermal environment while populations should not have been strongly perturbed by climatic oscillations, the main cause of geographic isolation at the surface. Methodology/Principal Finding: Samples of DNA sequences were obtained for seven nuclear loci and a mitochondrial locus in order to conduct a multi-locus analysis of divergence and gene flow between two closely related and hybridizing species of hydrothermal vent mussels, Bathymodiolus azoricus and B. puteoserpentis. The analysis revealed that (i) the two species have started to diverge approximately 0.760 million years ago, (ii) the B. azoricus population size was 2 to 5 time greater than the B. puteoserpentis and the ancestral population and (iii) gene flow between the two species occurred over the complete species range and was mainly asymmetric, at least for the chromosomal regions studied. Conclusions/Significance: A long history of gene flow has been detected between the two Bathymodiolus species. However, it proved very difficult to conclusively distinguish secondary introgression from ongoing parapatric differentiation. As powerful as coalescence approaches could be, we are left by the fact that natural populations often deviates from standard assumptions of the underlying model. A more direct observation of the history of recombination at one of the seven loci studied suggests an initial period of allopatric differentiation during which recombination was blocked between lineages. Even in the deep sea, geographic isolation may well be a crucial promoter of speciation.
Plos One (1932-6203) (Public Library Science), 2009-08 , Vol. 4 , N. 8 , P. 1-15

Droits : 2009 Faure et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
http://archimer.ifremer.fr/doc/00129/24012/21972.pdf
DOI:10.1371/journal.pone.0006485
http://archimer.ifremer.fr/doc/00129/24012/