Browsing by Author "Rozbaczylo, Nicolas"

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    DNA barcoding of marine polychaetes species of southern Patagonian fjords
    (2011) Maturana, Claudia S.; Moreno, Rodrigo A.; Labra, Fabio A.; Gonzalez-Wevar, Claudio A.; Rozbaczylo, Nicolas; Carrasco, Franklin D.; Poulin, Elie
    Accurate species identification remains a basic first step in any study of biodiversity, particularly for global changes and their consequences. Thus, there is a pressing need for taxonomic expertise in a broad range of taxa. DNA barcoding has proved to be a powerful alternative method to traditional morphological approaches, allowing to complement identification techniques for living organisms. In this study, we assess intraspecific and interspecific genetic divergence among marine polychaetes from Patagonian fjords of southern Chile, using mitochondrial Cytochrome c Oxidase Subunit I (COI) gene. Our results showed that a total of 13 polychaetes species identified in this study exhibited high levels of interspecific variation among 31 analyzed sequences. Mean pairwise sequence distances comparisons based on K2P within species ranged from 0.2 to 0.4%. In contrast, interspecific comparisons were much higher and ranged between 18 to 47%, with the exception of the congeneric species Asychis chilensis and Asychis amphiglypta that showed high levels of genetic similarities and absence of reciprocal monophyly. This study presents the first information on DNA barcoding for polychaetes species in the southern Chile, and it establishes the effectiveness of DNA barcoding for identification of marine polychaetes species from Patagonian Fjords, thus making it available to a much broader range of scientists.
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    Genetic identification of benthic polychaetes in a biodiversity hotspot in the southeast Pacific
    (2011) Canales-Aguirre, Cristian B.; Rozbaczylo, Nicolas; Hernandez, Cristian E.
    The aim of this study was to evaluate the utility of COI, of the mitochondrial DNA, for the taxonomic determination of soft-bottom benthic polychaetes in the Chiloe Inner Sea as a particularly important zone for polychaete fauna of the southeast Pacific. The results show high genetic differentiation between morphological species of polychaetes (posterior probabilities upper 0.9), and Onuphis pseudoiridescens showed the greatest divergence (3.08 +/- 0.08 S. D.). The results support the role of the COI gene as a useful molecular marker for fast and accurate taxonomic determination of benthic polychaetes. This study leads the way for research on the biodiversity and systematics of polychaetes off the Chilean coast using molecular phylogenetic criteria.
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    Morphological and molecular characterization of Perinereis gualpensis (Polychaeta: Nereididae) and its phylogenetic relationships with other species of the genus off the Chilean coast, Southeast Pacific
    (2013) Sampertegui, Sandra; Rozbaczylo, Nicolas; Canales-Aguirre, Cristian B.; Carrasco, Franklin; Hernandez, Cristian E.; Rodriguez-Serrano, Enrique
    The genus Perinereis, family Nereididae, consists of approximately 66 worldwide distributed species with marine, estuarine, and freshwater representatives. The objective of this study is to use morphological and molecular traits to evaluate the taxonomic differentiation of the estuarine polychaete P gualpensis. Also we reconstruct the phylogenetic relationships between P gualpensis and congeneric species recorded in Chilean coast: P. falklandica, P. longidonta and, especially with the morphologically most similar species, P vallata. Phylogenetic analyses based on molecular and morphological characters allow us to validate P. gualpensis and P. vallata as two independent and clearly defined species. Consequently, the taxonomic confusion about the possible sibling species P. gualpensis and P. vallata is completely resolved. However, morphological and genetic data are partially incongruent about the phylogenetic relationships of these four Perinereis species. We concluded that different evolutionary process that affect the morphological and genetics data produce different answers. Also we propose the use of new molecular evidence arising from molecular markers with different nucleotide substitution rate to that used here.
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    On some ecological aspects of the lugworm Abarenicola affinis chiliensis Wells, 1963 (Polychaeta: Scolecida: Arenicolidae) from shallow soft bottoms of northern Chile
    (2007) Moreno, Rodrigo A.; Rozbaczylo, Nicolas; Sepulveda, Roger D.; Marinkovic, Milko I.; Arntz, Wolf E.; Thatje, Sven
    We conducted an ecological study of a population of the polychaete Abarenicola affinis chiliensis in the shallow subtidal zone of Caleta Guardiamarina Riquelme in northern Chile. The study area is characterized by a hypoxic bottom consisting of fine sands and a silt-clay mixture, with high values of total organic matter content (TOM > 20%). During the two study periods (spring 1996 and 1997), the numerical contribution of A. affinis chiliensis to the total macrofauna was greater than 80%. A similar pattern was recorded for biomass, with A. affinis chiliensis surpassing 95% of the total macrofauna biomass. Statistical analyses did not detect significant differences in environmental and biotic variables between years (with the exception of salinity, which increased slightly), indicating temporal stability of these variables over the study period. Our results do not support the hypothesis of Wells that seawater temperatures act as a physical barrier impeding the dispersal of Abarenicola species. This hypothesis should be reexamined for some representatives of Abarenicola on the Pacific coast of South America.
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    Redescription of the sea anemones Anthopleura hermaphroditica and Bunodactis hermafroditica (Cnidaria: Anthozoa: Actiniaria) from Chile
    (2013) Spano, Carlos; Rozbaczylo, Nicolas; Haeussermann, Vreni; Bravo, Ricardo
    The Chilean sea anemones Anthopleura hermaphroditica and Bunodactis hermafroditica have been confused repeatedly due to ambiguity in the definition of their diagnostic features. The present article re-describes and compares both species in relation to their synonymic history by examining the external and internal anatomy of several specimens collected between Antofagasta and Chiloe. Although very similar, A. hermaphroditica and B. hermafroditica can be distinguished by the coloration patterns of the oral disc, development of verrucae, presence of zooxanthellae, and the cnidae of the column and the mesenterial filaments. Based on these differences, the authorship of Bunodactis hermafroditica belongs to Carlgren (1959) but because the type material does not match with the description; we designate a neotype that contains the features identified by this author. While the validity of acrorhagi to differentiate genera is questioned, some amendments to the terminology used in the diagnosis of Anthopleura and Bunodactis are proposed. Hence, we reject the synonymization of the genera Gyractis and Bunodactis, considering the latter as a valid genus until a proper review with the type material of Aulactinia is made. In addition, the remarkable anatomical differences observed among populations of Anthopleura hermaphroditica suggest the presence of at least two distinct species.