Testing species boundaries between Atlantic and Pacific lineages of the Patagonian rockfish Sebastes oculatus (Teleostei: Scorpaenidae) through mitochondrial DNA sequences

Abstract

Resumen.-Se investigó la diferenciación genética y límites de especies entre los linajes Atlántico y Pacífico de Sebastes oculatus a través de secuencias de la región D-loop del ADN mitocondrial (541 bp). Las secuencias se obtuvieron de 47 individuos de siete localidades de las costas del Pacífico y Atlántico de Sudamérica (S. oculatus) y una localidad de Sudáfrica (S. capensis). Adicionalmente, se obtuvieron dos secuencias de Helicolenus lengerichi que fueron utilizadas como grupo externo. Estos datos fueron combinados con secuencias disponibles en GenBank correspondientes a 21 especies de Sebastes. Las aproximaciones de máxima verosimilitud y análisis Bayesiano mostraron distintividad topológica entre las poblaciones sudamericanas y africanas de Sebastes, apoyando la existencia de dos especies filogenéticas: S. oculatus y S. capensis. Sin embargo, las poblaciones del Pacífico y del Atlántico de S. oculatus no formaron grupos monofiléticos recíprocos. La aplicación del protocolo de Wiens & Penkrot para evaluar límites entre especies no apoyó la existencia de dos especies en las costas de Sudamérica. El flujo génico entre las poblaciones de S. oculatus podría ser explicado por una extensa dispersión larval favorecida tanto por la corriente de Humboldt y la Corriente de la Deriva del Oeste a lo largo de las costas de Sudamérica. Palabras clave: Hemisferio sur, cabrilla, mtDNA, especiaciónAbstract.-Genetic differentiation and species boundaries between Atlantic and Pacific lineages of the Patagonian rockfish Sebastes oculatus was investigated using mtDNA D-loop partial sequences (541 bp). Sequences were obtained for 47 individuals from seven locations off the Pacific and Atlantic coasts of South America (S. oculatus) and one off the coast of South Africa (S. capensis), and for two specimens of Helicolenus lengerichi (outgroup). These data were then combined with sequences from GenBank corresponding to 21 Sebastes species. Maximum likelihood and Bayesian phylogenetic approaches showed topological distinctiveness between South American and South African Sebastes populations, supporting the existence of two phylogenetic species: S. oculatus and S. capensis. However, Atlantic and Pacific populations of S. oculatus, did not form reciprocal monophyletic assemblages. Application of the Wiens & Penkrot's protocol to test species boundaries within this species did not support the existence of two different phylogenetic taxa. Gene flow between Atlantic and Pacific populations of S. oculatus could be explained by extensive larval dispersal, favored by both the Humboldt current and the West Wind Drift current along the South American coast.

Phylogeography and species distribution modelling reveal the effects of the Pleistocene ice ages on an intertidal limpet from the south‐eastern Pacific

“…According to the expansion‐contraction model (Provan & Bennett, ), the typical star‐like genealogy and demographic inference of the southern lineage indicates a sudden expansion (Figures a,b and b). A demographic response of this type has also been proposed for other species in southern South America (Ceballos et al., ; González‐Wevar et al., ; Nuñez, González, & Pérez‐Losada, ). The modelled ice sheet for southern South America would have reached the continental shelf south of 43° S (Hulton et al., ), implying habitat loss (local extinctions) for S. lessonii in this region.…”

Towards a model of postglacial biogeography in shallow marine species along the Patagonian Province: lessons from the limpet Nacella magellanica (Gmelin, 1791)

“…In contrast, few studies have established the importance of the developmental mode in the phylogeographic patterns of marine invertebrates in Patagonia. Absence of genetic structure, as observed in N. magellanica in Pacific Patagonia, have been also recognized in other marine organisms with indirect development, including the mytilid Mytilus edulis [94], fishes like Eleginops maclovinus [19] and Sebastes oculatus [95], and in macroalgae including Durvillaea antartica [15] and Macrocystis pyrifera [38]. These studies contrast with the results obtained in the direct developer Acanthina monodon that exhibits marked differentiation between northern and southern Pacific Patagonia localities [39].…”

Genetics, Gene Flow, and Glaciation: The Case of the South American Limpet Nacella mytilina

“…Hence, the duration of these dispersal stages is expected to correlate with the dispersal ability and with the genetic structure of the organism [ 112 – 114 ]. Absence of genetic structure along PP has been registered in several Patagonian marine organisms with high dispersal potential including invertebrates [ 25 , 115 – 117 ] fishes [ 32 , 35 , 118 ], and macroalgae [ 46 , 48 , 100 , 119 ]. Regretfully, no direct information about larval duration in Patagonian species of Nacella exist but it is expected that their development should be similar to the Antarctic relative N .…”