title: SEX RATIO VARIATION IN THE LESSONIA NIGRESCENS COMPLEX (LAMINARIALES, PHAEOPHYCEAE): EFFECT OF LATITUDE, TEMPERATURE, AND MARGINALITY(1).
abstract: 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°-30° 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°C than at 10°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).
authors.affiliation: Departamento de Ecología, Center for Advanced Studies in Ecology and Biodiversity, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Post-code 6513677, Santiago, Chile, UPMC Univ. Paris 06, UMR 7144, Equipe "BEDIM", Station Biologique de Roscoff, 29682 Roscoff, France, CNRS, UMR 7144, Station Biologique de Roscoff, Place Georges Teissier, 29682 Roscoff, FranceDepartamento de Ecología, Center for Advanced Studies in Ecology and Biodiversity, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Post-code 6513677, Santiago, ChileDepartamento de Ecología, Center for Advanced Studies in Ecology and Biodiversity, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Post-code 6513677, Santiago, Chile, UPMC Univ. Paris 06, CNRS, UMR 7144, Equipe "BEDIM", Station Biologique de Roscoff, 29682 Roscoff, France, CEAZA, Facultad de Ciencias del Mar, Universidad Católica del Norte, Larrondo 1281, Coquimbo, Chile UPMC Univ. Paris 06, UMR 7144, Equipe "BEDIM", Station Biologique de Roscoff, 29682 Roscoff, France CNRS, UMR 7144, Station Biologique de Roscoff, Place Georges Teissier, 29682 Roscoff, France.
authors.forename: Luz
authors.initials: L
authors.lastname: Valeria Oppliger
authors.affiliation: Departamento de Ecología, Center for Advanced Studies in Ecology and Biodiversity, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Post-code 6513677, Santiago, Chile, UPMC Univ. Paris 06, UMR 7144, Equipe "BEDIM", Station Biologique de Roscoff, 29682 Roscoff, France, CNRS, UMR 7144, Station Biologique de Roscoff, Place Georges Teissier, 29682 Roscoff, FranceDepartamento de Ecología, Center for Advanced Studies in Ecology and Biodiversity, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Post-code 6513677, Santiago, ChileDepartamento de Ecología, Center for Advanced Studies in Ecology and Biodiversity, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Post-code 6513677, Santiago, Chile, UPMC Univ. Paris 06, CNRS, UMR 7144, Equipe "BEDIM", Station Biologique de Roscoff, 29682 Roscoff, France, CEAZA, Facultad de Ciencias del Mar, Universidad Católica del Norte, Larrondo 1281, Coquimbo, Chile UPMC Univ. Paris 06, UMR 7144, Equipe "BEDIM", Station Biologique de Roscoff, 29682 Roscoff, France CNRS, UMR 7144, Station Biologique de Roscoff, Place Georges Teissier, 29682 Roscoff, France.
authors.forename: Juan A
authors.initials: JA
authors.lastname: Correa
authors.affiliation: Departamento de Ecología, Center for Advanced Studies in Ecology and Biodiversity, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Post-code 6513677, Santiago, Chile, UPMC Univ. Paris 06, UMR 7144, Equipe "BEDIM", Station Biologique de Roscoff, 29682 Roscoff, France, CNRS, UMR 7144, Station Biologique de Roscoff, Place Georges Teissier, 29682 Roscoff, FranceDepartamento de Ecología, Center for Advanced Studies in Ecology and Biodiversity, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Post-code 6513677, Santiago, ChileDepartamento de Ecología, Center for Advanced Studies in Ecology and Biodiversity, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Post-code 6513677, Santiago, Chile, UPMC Univ. Paris 06, CNRS, UMR 7144, Equipe "BEDIM", Station Biologique de Roscoff, 29682 Roscoff, France, CEAZA, Facultad de Ciencias del Mar, Universidad Católica del Norte, Larrondo 1281, Coquimbo, Chile UPMC Univ. Paris 06, UMR 7144, Equipe "BEDIM", Station Biologique de Roscoff, 29682 Roscoff, France CNRS, UMR 7144, Station Biologique de Roscoff, Place Georges Teissier, 29682 Roscoff, France.
authors.forename: Sylvain
authors.initials: S
authors.lastname: Faugeron
authors.affiliation: Departamento de Ecología, Center for Advanced Studies in Ecology and Biodiversity, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Post-code 6513677, Santiago, Chile, UPMC Univ. Paris 06, UMR 7144, Equipe "BEDIM", Station Biologique de Roscoff, 29682 Roscoff, France, CNRS, UMR 7144, Station Biologique de Roscoff, Place Georges Teissier, 29682 Roscoff, FranceDepartamento de Ecología, Center for Advanced Studies in Ecology and Biodiversity, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Post-code 6513677, Santiago, ChileDepartamento de Ecología, Center for Advanced Studies in Ecology and Biodiversity, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Post-code 6513677, Santiago, Chile, UPMC Univ. Paris 06, CNRS, UMR 7144, Equipe "BEDIM", Station Biologique de Roscoff, 29682 Roscoff, France, CEAZA, Facultad de Ciencias del Mar, Universidad Católica del Norte, Larrondo 1281, Coquimbo, Chile UPMC Univ. Paris 06, UMR 7144, Equipe "BEDIM", Station Biologique de Roscoff, 29682 Roscoff, France CNRS, UMR 7144, Station Biologique de Roscoff, Place Georges Teissier, 29682 Roscoff, France.
authors.forename: Jessica
authors.initials: J
authors.lastname: Beltrán
authors.affiliation: Departamento de Ecología, Center for Advanced Studies in Ecology and Biodiversity, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Post-code 6513677, Santiago, Chile, UPMC Univ. Paris 06, UMR 7144, Equipe "BEDIM", Station Biologique de Roscoff, 29682 Roscoff, France, CNRS, UMR 7144, Station Biologique de Roscoff, Place Georges Teissier, 29682 Roscoff, FranceDepartamento de Ecología, Center for Advanced Studies in Ecology and Biodiversity, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Post-code 6513677, Santiago, ChileDepartamento de Ecología, Center for Advanced Studies in Ecology and Biodiversity, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Post-code 6513677, Santiago, Chile, UPMC Univ. Paris 06, CNRS, UMR 7144, Equipe "BEDIM", Station Biologique de Roscoff, 29682 Roscoff, France, CEAZA, Facultad de Ciencias del Mar, Universidad Católica del Norte, Larrondo 1281, Coquimbo, Chile UPMC Univ. Paris 06, UMR 7144, Equipe "BEDIM", Station Biologique de Roscoff, 29682 Roscoff, France CNRS, UMR 7144, Station Biologique de Roscoff, Place Georges Teissier, 29682 Roscoff, France.
authors.forename: Florence
authors.initials: F
authors.lastname: Tellier
authors.affiliation: Departamento de Ecología, Center for Advanced Studies in Ecology and Biodiversity, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Post-code 6513677, Santiago, Chile, UPMC Univ. Paris 06, UMR 7144, Equipe "BEDIM", Station Biologique de Roscoff, 29682 Roscoff, France, CNRS, UMR 7144, Station Biologique de Roscoff, Place Georges Teissier, 29682 Roscoff, FranceDepartamento de Ecología, Center for Advanced Studies in Ecology and Biodiversity, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Post-code 6513677, Santiago, ChileDepartamento de Ecología, Center for Advanced Studies in Ecology and Biodiversity, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Post-code 6513677, Santiago, Chile, UPMC Univ. Paris 06, CNRS, UMR 7144, Equipe "BEDIM", Station Biologique de Roscoff, 29682 Roscoff, France, CEAZA, Facultad de Ciencias del Mar, Universidad Católica del Norte, Larrondo 1281, Coquimbo, Chile UPMC Univ. Paris 06, UMR 7144, Equipe "BEDIM", Station Biologique de Roscoff, 29682 Roscoff, France CNRS, UMR 7144, Station Biologique de Roscoff, Place Georges Teissier, 29682 Roscoff, France.
authors.forename: Myriam
authors.initials: M
authors.lastname: Valero
authors.affiliation: Departamento de Ecología, Center for Advanced Studies in Ecology and Biodiversity, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Post-code 6513677, Santiago, Chile, UPMC Univ. Paris 06, UMR 7144, Equipe "BEDIM", Station Biologique de Roscoff, 29682 Roscoff, France, CNRS, UMR 7144, Station Biologique de Roscoff, Place Georges Teissier, 29682 Roscoff, FranceDepartamento de Ecología, Center for Advanced Studies in Ecology and Biodiversity, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Post-code 6513677, Santiago, ChileDepartamento de Ecología, Center for Advanced Studies in Ecology and Biodiversity, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Post-code 6513677, Santiago, Chile, UPMC Univ. Paris 06, CNRS, UMR 7144, Equipe "BEDIM", Station Biologique de Roscoff, 29682 Roscoff, France, CEAZA, Facultad de Ciencias del Mar, Universidad Católica del Norte, Larrondo 1281, Coquimbo, Chile UPMC Univ. Paris 06, UMR 7144, Equipe "BEDIM", Station Biologique de Roscoff, 29682 Roscoff, France CNRS, UMR 7144, Station Biologique de Roscoff, Place Georges Teissier, 29682 Roscoff, France.
authors.forename: Christophe
authors.initials: C
authors.lastname: Destombe
keywords: Lessonia nigrescens; Phaeophyceae; cryptic species; gametophyte; latitude; marginal populations; sex determination; sex ratio; temperature