From Settlers to Subspecies: Genetic Differentiation in Commerson’s Dolphins Between South America and the Kerguelen Islands

Type Article
Date 2021-12
Language English
Author(s) Kraft Sebastián1, Pérez-Alvarez Mjosé1, 2, 3, 4, Olavarría Carlos3, 5, Moraga Rodrigo3, Baker C. Scott6, Steel Debbie6, Tixier Paul7, 8, Guinet Christophe8, Viricel Amelia9, Brickle Paul10, Costa Marina11, Crespo Enrique11, Durante Cristian11, Loizaga Rocio11, Poulin Elie1, 4
Affiliation(s) 1 : Laboratorio de Ecología Molecular, Facultad de Ciencias, Instituto de Ecología y Biodiversidad (IEB), Universidad de Chile, Santiago, Chile
2 : Facultad de Ciencias, Escuela de Medicina Veterinaria, Universidad Mayor, Santiago, Chile
3 : Centro de Investigación Eutropia, Santiago, Chile
4 : Millennium Institute Biodiversity of Antarctic and Subantarctic Ecosystems (BASE), Santiago, Chile
5 : Centro de Estudios Avanzados en Zonas Áridas (CEAZA), La Serena, Chile
6 : Marine Mammal Institute, Oregon State University, Newport, OR, United States
7 : MARBEC, Université de Montpellier-CNRS-IFREMER-IRD, Séte, France
8 : Centre d’Etudes Biologiques de Chizé (CEBC) CNRS-ULR, UMR 7273, Villiers-en-Bois, France
9 : Littoral Environnement et Sociétés (LIENSs), UMR 7266, CNRS-Université de la Rochelle, La Rochelle, France
10 : South Atlantic Environmental Research Institute (SAERI), Stanley Cottage, Stanley, Falkland Islands
11 : Laboratorio de Mamíferos Marinos, Centro para el Estudio de Sistemas Marinos (CESIMAR-CONICET), Puerto Madryn, Argentina
Source Frontiers In Marine Science (2296-7745) (Frontiers Media SA), 2021-12 , Vol. 8 , P. 782512 (11p.)
DOI 10.3389/fmars.2021.782512
WOS© Times Cited 1
Keyword(s) Cephalorhynchus commersonii, colonization, divergence, last glacial maximum, mitochondrial DNA, phylogeography

Commerson’s dolphins (Cephalorhynchus commersonii) are separated into the subspecies C. c. commersonii, found along southern South America (SA) and the Falkland Islands/Islas Malvinas (FI/IM), and C. c. kerguelenensis, restricted to the subantarctic Kerguelen Islands (KI). Following the dispersal model proposed for the genus, the latter is thought to have originated from SA after a long-distance dispersal event. To evaluate this biogeographic scenario, a distribution-wide, balanced sampling of mitochondrial DNA (mtDNA) control region sequences was designed. New tissue samples from southern Chile, Argentina, FI/IM, and KI were added to published sequences from SA and KI, for a total of 256 samples. Genetic diversity indices, genetic and phylogeographic structure, and migration rates were calculated. One haplotype was shared between subspecies, with which all haplotypes of C. c. kerguelenensis formed a distinct group in the haplotype network. A new haplotype for C. c. kerguelenensis is reported. Differentiation in haplotype frequencies was found among localities within the distribution of C. c. commersonii, yet the phylogeographic signal was only statistically significant between subspecies. Coalescent-based historical gene flow estimations indicated migration between the northern and southern portions of the species’ range in SA as well as between SA and the FI/IM, but not between these and the KI. The net nucleotide divergence between dolphins from SA and the FI/IM was lower than the recommended threshold value suggested for delimiting subspecies, unlike that found between C. c. commersonii and C. c. kerguelenensis. The results are consistent with the model of post-glacial colonization of KI by South American C. commersonii, followed by an ongoing divergence process and subspecies status. Thus, C. c. kerguelenensis may represent the most recent diversification step of Cephalorhynchus, where isolation from their source population is driving a process of incipient speciation.

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Kraft Sebastián, Pérez-Alvarez Mjosé, Olavarría Carlos, Moraga Rodrigo, Baker C. Scott, Steel Debbie, Tixier Paul, Guinet Christophe, Viricel Amelia, Brickle Paul, Costa Marina, Crespo Enrique, Durante Cristian, Loizaga Rocio, Poulin Elie (2021). From Settlers to Subspecies: Genetic Differentiation in Commerson’s Dolphins Between South America and the Kerguelen Islands. Frontiers In Marine Science, 8, 782512 (11p.). Publisher's official version : , Open Access version :