Browsing by Author "Montecinos, Alejandro E."

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    Impact of persistent barrier to gene flow and catastrophic events on red algae evolutionary history along the Chilean coast
    (2024) Huanel, Oscar R.; Montecinos, Alejandro E.; Sepulveda-Espinoza, Francisco; Guillemin, Marie-Laure
    Historical vicariance events, linked to the existence of stable physical barriers to gene flow, generate concordant genetic breaks in co-distributed species while stochastic processes (e.g., costal uplift) could cause species-specific genetic breaks as a result of local strong demographic bottlenecks or extinction. In Chile, previous studies show that the area of the 30 degrees S-33 degrees S could correspond to a stable barrier to gene flow that have affected the genetic structure of various algae and marine invertebrates. Here we sequenced two organellar genes (COI and rbcL) in four taxonomically accepted co-distributed red seaweeds species characterized by a low dispersal potential: Mazzaella laminarioides, M. membranacea, Asterfilopsis disciplinalis, and Ahnfeltiopsis vermicularis. Our results revealed the existence of ten strongly differentiated linages in the taxa studied. Strong genetic breaks, concordant in both space and time (divergence estimated to have occurred some 2.9-12.4 million years ago), were observed between taxa distributed across the 33 degrees S. Conversely, in the Central/South part of the Chilean coast, the localization of the genetic breaks/sub-structure observed varied widely (36 degrees S, 38 degrees S, 39 degrees S, and 40 degrees S). These results suggest that a major historical vicariance event has modeled the genetic structure of several Chilean marine organisms in the north of the Chilean coast during the mid-Miocene, while more recent stochastic events and genetic drift could be the driving forces of genetic divergence/structuration in the central-southern part of the coast.
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    Molecular data reveal the presence of three Plocamium Lamouroux species with complex patterns of distribution in Southern Chile
    (2021) Montecinos, Alejandro E.; Huanel, Oscar R.; Ramirez, Maria E.; Guillemin, Marie-Laure
    Plocamium Lamouroux is a widespread genus for which 45 species are currently recognized. However, classical taxonomy based only on morphological characters, is problematic within this genus. The use of molecular tools has uncovered cryptic genetic species, mistakenly grouped under the name of morphological species that are common and widespread (induding the generitype Plocamium cartilagineum (Linnaeus) P.S.Dixon). The aim of this work was to evaluate the species diversity of Plocamium in Southern Chile. For this purpose, three independent molecular markers were sequenced in samples collected from seven populations located between 41 degrees S and 54 degrees S. The species diversity was evaluated using phylogenetic reconstructions and two independent methods for species delimitation (ABGD and GMYC). The outcomes of each method were congruent, suggesting the presence of three species in Southern Chile. One species, named Plocamium sp. 1, is restricted to Punta Guaban, the only locality sampled north of the biogeographic barrier of the 42 degrees S. The other two species, Plocamium sp. 2 and 3 are distributed in sympatry in Patagonia and Tierra del Fuego. The three Chilean species form a Bade phylogenetically close to sequences obtained from New Zealand and Australia and a divergence along the coasts of Chile after past transoceanic dispersal is proposed. We propose that divergence in glacial microrefugia could have subsequently happen in the southern part of the coast, this hypothesis being supported by the strong impact of glacial maxima on population dynamics, especially in Plocamium sp. 3.