Browsing by Author "Tellier, Florence"

Now showing 1 - 6 of 6
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    Development and characterization of nine polymorphic microsatellite markers in the Chilean kelp Lessonia nigrescens
    (2009) Faugeron, Sylvain; Veliz, David; Peralta, Gioconda; Tapia, Javier; Tellier, Florence; Billot, Claire; Martinez, Enrique
    A total of nine microsatellite loci were isolated and characterized in the Chilean kelp Lessonia nigrescens Bory. Using two different enriched libraries, we observed 1-14 alleles per locus in two samples of 21 kelp individuals each. The observed heterozygosities ranged from 0.05 to 0.80 and all loci are in Hardy-Weinberg equilibrium for one or both samples. Seventeen samples collected from different sites showed high allele diversity along the species distribution. The variation detected at these markers is currently being used for the study of populations of Lessonia nigrescens at different geographical scales.
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    Phylogeographic analyses of the 30°S south-east Pacific biogeographic transition zone establish the occurrence of a sharp genetic discontinuity in the kelp Lessonia nigrescens: Vicariance or parapatry?
    (2009) Tellier, Florence; Meynard, Andres P.; Correa, Juan A.; Faugeron, Sylvain; Valero, Myriam
    Phylogeographic studies are lacking in the Southern Hemisphere, and in particular in the south-eastern Pacific. To infer the possible scenario for the debated biogeographic transition zone located at 30-33 degrees S along the Chilean coast, we investigated whether there is a concordance between the phylogeographic pattern and the biogeographic transition in the intertidal kelp Lessonia nigrescens; whose distribution is continuous across this transition zone. Using a combination of four makers located in the three genomic compartments (chloroplast, mitochondria and nucleus), we showed the presence of two main divergent lineages, possibly cryptic species. There was an exact match of the phylogeographic break with the 30 degrees S biogeographic transition zone, suggesting a common origin. The combined information given by the multilocus approach and by the population analysis suggested the occurrence of a budding speciation, with a northward range expansion. (C) 2009 Elsevier Inc. All rights reserved.
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    Possible role of a mitochondrial genome rearrangement in maintaining the spatial segregation of two cryptic species of the Lessonia nigrescens species complex
    (2011) Tellier, Florence; Faugeron, Sylvain; Valero, Myriam
    In numerous taxa, studies have reported the co-occurrence of several copies for a single mitochondrial marker (heteroplasmy), leading to incorrect phylogenetic inferences if not detected. While this phenomenon has been widely investigated in terrestrial taxa, it remains largely unexplored in marine algae. Here we report the detection of heteroplasmy in the Lessonia nigrescens species complex. This work aimed to identify the distinct fragments and to determine their geographic extent in the distribution range of two kelp species. Using phylogenetic reconstructions of a mitochondria! DNA marker (atp8/trnS intergenic region), we suggest that a duplication event occurred, either with or without transfer of the copy to the nucleus. The corresponding sequences constituted a new monophyletic clade, distinct from those previously described in L. nigrescens, hence discarding the interspecific hybridization and intraspecific biparental transmission hypotheses. The characterization of 652 individuals sampled along 2,500 km of coastline revealed that the duplication was absent in the Northern species, but of high frequency in the northernmost populations of the Southern species. Because the duplication is restricted to the parapatric contact zone between the two species, our findings open new perspectives about the importance of reproductive isolation mechanisms and local adaptation in the origin and persistence of this pattern.
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    SEX RATIO VARIATION IN THE LESSONIA NIGRESCENS COMPLEX (LAMINARIALES, PHAEOPHYCEAE): EFFECT OF LATITUDE, TEMPERATURE, AND MARGINALITY
    (WILEY, 2011) Oppliger, Luz Valeria; Correa, Juan A.; Faugeron, Sylvain; Beltran, Jessica; Tellier, Florence; Valero, Myriam; Destombe, Christophe
    Little is known about variation of sex ratio, the proportion of males to females, in natural populations of seaweed, though it is a major determinant of the mating system. The observation of sexual chromosomes in kelps suggested that sex is partly genetically determined. However, it is probably not purely genetic since the sex ratio can be modified by environmental factors such as salinity or temperature. In this paper, sex ratio variation was studied in the kelp Lessonia nigrescens Bory complex, recently identified as two cryptic species occurring along the Chilean coast: one located north and the other south of the biogeographic boundary at latitude 29 degrees-30 degrees S. The life cycle of L. nigrescens is characterized by an alternation of microscopic haploid gametophytic individuals and large macroscopic fronds of diploid sporophytes. The sex ratio was recorded in progenies from 241 sporophytic individuals collected from 13 populations distributed along the Chilean coast in order (i) to examine the effect of an environmental gradient coupled with latitude, and (ii) to compare marginal populations to central populations of the two species. In addition, we tested the hypothesis that the sex ratios of the two cryptic species would be affected differently by temperature. First, our results demonstrate that sex ratio seems to be mainly genetically determined and temperature can significantly modify it. Populations of the northern species showed a lower frequency of males at 14 degrees C than at 10 degrees C, whereas populations of the southern species showed the opposite pattern. Second, both species displayed an increased variation in sex ratio at the range limits. This greater variation at the margins could be due either to differential mortality between sexes or to geographic parthenogenesis (asexual reproduction).
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    Species replacement along a linear coastal habitat: phylogeography and speciation in the red alga Mazzaella laminarioidesalong the south east pacific
    (2012) Montecinos, Alejandro; Broitman Rojas, Bernardo Óscar; Faugeron, Sylvain Wielfrid; Haye, Pilar A; Tellier, Florence; Guillemin, Marie-Laure
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    The importance of having two species instead of one in kelp management: the Lessonia nigrescens species complex
    (2011) Tellier, Florence; Alonso Vega, J. M.; Broitman, Bernardo R.; Vasquez, Julio A.; Valero, Myriam; Faugeron, Sylvain
    Natural resource management requires extensive knowledge of the biology of the organisms and their responses to ecological and anthropogenic processes. While species are commonly used as management units, the presence of cryptic species morphologically indistinguishable, but with different biological characteristics may hinder the design of appropriate management and conservation measures. Thus, correctly assigning individuals to species is of particular importance and challenges current management approaches in seaweeds, which are highly plastic morphologically. After a synthesis of the species definitions, we show an example of the challenges of managing cryptic species with the Chilean kelp Lessonia nigrescens. We review phylogenetic, biological and ecological evidence indicating that this economically important intertidal species is composed of two cryptic species. In the face of increasing global demand for kelp, an intensified impact of harvesting pressure is observed around the region where both cryptic species find their northern and southern edge of their geographic distributions, around 30 S. We recommend special management strategies targeting harvested areas around such range edge populations. Our synthesis highlights the importance of having two species that are ecologically and genetically different. In addition, the cryptic species may diverge in biochemical composition, opening new perspectives for the alginates' industry. The capacity of conservation and management programs to correctly distinguish new species is of particular importance as numerous cryptic species are constantly being discovered in seaweeds, including kelps.