Several studies have reported a negative association between developmental stability and parasiti... more Several studies have reported a negative association between developmental stability and parasitic infection. However, the host-parasite associations examined so far consist only of a limited number of parasite taxa, and developmental stability was appraised on definitive hosts. The present study examines the association between infection by 2 acanthocephalan parasites. Pomphorhynchus laevis and Polymorphus minutus, and the developmental stability of their common intermediate host Gammarus pulex. Developmental stability was estimated from the fluctuating asymmetry (FA) levels of 6 morphological traits. A positive association was found between FA and infection. Infected gammarids tended to be more asymmetrical than the noninfected ones for an index generated by combining FA scores from 2 characters out of the 6 studied, even though no significant relationships were found between FA levels and parasitic loads. The simultaneous presence of both acanthocephalan species in the same host seems to be associated with increased FA levels of gammarids, but this trend was not statistically significant. For the same characters, males exhibited higher levels of FA than females.
HAL (Le Centre pour la Communication Scientifique Directe), Jun 21, 2013
92 pagesComprendre comment les divergences entre groupes d'organismes peuvent aboutir à l'... more 92 pagesComprendre comment les divergences entre groupes d'organismes peuvent aboutir à l'apparition d'espèces nouvelles est un problème majeur en Evolution. Les exemples développés dans le présent ouvrage se placent au centre de cette thématique. Ils traitent de l'étude de la différenciation des populations et de la spéciation par le biais d'approches morphométriques (morphométrie traditionnelle et morphométrie géométrique) ainsi que sur l'étude des mécanismes de contrôle de la variation phénotypique. Ces études s'articulent autour de trois axes principaux complémentaires: (1) la quantification morphométrique de la différenciation et sa mise en relation avec les patrons de différenciation génétique et l'histoire évolutive des taxons considérés. (2) l'évaluation de l'impact de la différenciation morphologique sur la spéciation par l'étude de l'instabilité de développement des hybrides entre taxons en voie de différenciation (3) l'étude des mécanismes sous-jacents à l'instabilité de développement. Chacun de ces axes constitue une partie distincte de l'ouvrage
The rheophilic genus Steatocranus Boulenger, 1899 (Cichlidae: Pseudocrenilabrinae: Steatocranini)... more The rheophilic genus Steatocranus Boulenger, 1899 (Cichlidae: Pseudocrenilabrinae: Steatocranini) currently comprises nine valid species distributed in rapids of the Central and Lower Congo basin and in the Volta Basin. Molecular phylogenetic analyses based on mitochondrial, and nuclear DNA sequences as well as on anonymous multilocus DNA fragment analyses (AFLPs) in combination with digital and classic morphometric analyses revealed the existence of at least 19 diagnosable Steatocranus-lineages in the Lower Congo, which are currently being described or redescribed as species-level taxa. The Volta-River species Steatocranus irvinei is not closely related to the Congo-Steatocranus, but is related to a West African haplotilapiine tribe Gobiocichlini, and consequently will be transferred to a new genus. A subgroup of the true Steatocranus has formed an eco-morphologically diverse miniature species flock along the Lower Congo rapids. Explicit tests for ancient reticulations based on AFLP multilocus data strongly suggest, that at least one taxon of the Lower Congo, S. glaber, is of hybrid origin, and that multiple additional reticulations have taken place in the course of cladogenesis of Steatocranus. The extent of reticulations in the phylogeny of Steatocranus, as well as in other rheophilic cichlid taxa at the base of the East African cichlid radiations has manifold implications not only for the potential hybrid origin of the cichlid radiations but also for the monophyly criterion as the conceptual basis for the description of higher cichlid taxa.
The surroundings of the Cortiou sewage are among the most polluted environments of the French Med... more The surroundings of the Cortiou sewage are among the most polluted environments of the French Mediterranean Sea (Marseilles, France). So far, no studies have precisely quantified the impact of pollution on the development of organisms in this area.Methods: We used a fluctuating asymmetry (FA) measure of developmental instability (DI) to assess environmental stress in two species of radially symmetric sea urchins (Arbacia lixula and Paracentrotus lividus). For six sampling sites (Cortiou, Riou, Maire, East Maire, Mejean, and Niolon), levels of FA were calculated from continuous and discrete skeletal measures of ambulacral length, number of pore pairs and primary tubercles.Results: For both species, the most polluted sampling site, Cortiou, displayed the highest level of FA, while the Maire and East Maire sampling sites displayed the lowest levels. A. lixula revealed systematic differences in FA among sampling sites for all characters and P. lividus showed differences in FA for the number of primary tubercles.Conclusions: Statistical analyses of FA show a concordance between the spatial patterns of FA among sampling sites and the spatial distribution of sewage discharge pollutants in the Cortiou area. High developmental stress in these sampling sites is associated with exposure to high concentrations of heavy metals and many harmful organic substances contained in wastewater. FA estimated from structures with complex symmetry appears to be a fast and reliable tool to detect subtle differences in FA. Its use in biomonitoring programs for inferring anthropogenic and natural environmental stress is suggested.
Several studies have reported a negative association between developmental stability and parasiti... more Several studies have reported a negative association between developmental stability and parasitic infection. However, the host-parasite associations examined so far consist only of a limited number of parasite taxa, and developmental stability was appraised on definitive hosts. The present study examines the association between infection by 2 acanthocephalan parasites. Pomphorhynchus laevis and Polymorphus minutus, and the developmental stability of their common intermediate host Gammarus pulex. Developmental stability was estimated from the fluctuating asymmetry (FA) levels of 6 morphological traits. A positive association was found between FA and infection. Infected gammarids tended to be more asymmetrical than the noninfected ones for an index generated by combining FA scores from 2 characters out of the 6 studied, even though no significant relationships were found between FA levels and parasitic loads. The simultaneous presence of both acanthocephalan species in the same host seems to be associated with increased FA levels of gammarids, but this trend was not statistically significant. For the same characters, males exhibited higher levels of FA than females.
HAL (Le Centre pour la Communication Scientifique Directe), Jun 21, 2013
92 pagesComprendre comment les divergences entre groupes d'organismes peuvent aboutir à l'... more 92 pagesComprendre comment les divergences entre groupes d'organismes peuvent aboutir à l'apparition d'espèces nouvelles est un problème majeur en Evolution. Les exemples développés dans le présent ouvrage se placent au centre de cette thématique. Ils traitent de l'étude de la différenciation des populations et de la spéciation par le biais d'approches morphométriques (morphométrie traditionnelle et morphométrie géométrique) ainsi que sur l'étude des mécanismes de contrôle de la variation phénotypique. Ces études s'articulent autour de trois axes principaux complémentaires: (1) la quantification morphométrique de la différenciation et sa mise en relation avec les patrons de différenciation génétique et l'histoire évolutive des taxons considérés. (2) l'évaluation de l'impact de la différenciation morphologique sur la spéciation par l'étude de l'instabilité de développement des hybrides entre taxons en voie de différenciation (3) l'étude des mécanismes sous-jacents à l'instabilité de développement. Chacun de ces axes constitue une partie distincte de l'ouvrage
The rheophilic genus Steatocranus Boulenger, 1899 (Cichlidae: Pseudocrenilabrinae: Steatocranini)... more The rheophilic genus Steatocranus Boulenger, 1899 (Cichlidae: Pseudocrenilabrinae: Steatocranini) currently comprises nine valid species distributed in rapids of the Central and Lower Congo basin and in the Volta Basin. Molecular phylogenetic analyses based on mitochondrial, and nuclear DNA sequences as well as on anonymous multilocus DNA fragment analyses (AFLPs) in combination with digital and classic morphometric analyses revealed the existence of at least 19 diagnosable Steatocranus-lineages in the Lower Congo, which are currently being described or redescribed as species-level taxa. The Volta-River species Steatocranus irvinei is not closely related to the Congo-Steatocranus, but is related to a West African haplotilapiine tribe Gobiocichlini, and consequently will be transferred to a new genus. A subgroup of the true Steatocranus has formed an eco-morphologically diverse miniature species flock along the Lower Congo rapids. Explicit tests for ancient reticulations based on AFLP multilocus data strongly suggest, that at least one taxon of the Lower Congo, S. glaber, is of hybrid origin, and that multiple additional reticulations have taken place in the course of cladogenesis of Steatocranus. The extent of reticulations in the phylogeny of Steatocranus, as well as in other rheophilic cichlid taxa at the base of the East African cichlid radiations has manifold implications not only for the potential hybrid origin of the cichlid radiations but also for the monophyly criterion as the conceptual basis for the description of higher cichlid taxa.
The surroundings of the Cortiou sewage are among the most polluted environments of the French Med... more The surroundings of the Cortiou sewage are among the most polluted environments of the French Mediterranean Sea (Marseilles, France). So far, no studies have precisely quantified the impact of pollution on the development of organisms in this area.Methods: We used a fluctuating asymmetry (FA) measure of developmental instability (DI) to assess environmental stress in two species of radially symmetric sea urchins (Arbacia lixula and Paracentrotus lividus). For six sampling sites (Cortiou, Riou, Maire, East Maire, Mejean, and Niolon), levels of FA were calculated from continuous and discrete skeletal measures of ambulacral length, number of pore pairs and primary tubercles.Results: For both species, the most polluted sampling site, Cortiou, displayed the highest level of FA, while the Maire and East Maire sampling sites displayed the lowest levels. A. lixula revealed systematic differences in FA among sampling sites for all characters and P. lividus showed differences in FA for the number of primary tubercles.Conclusions: Statistical analyses of FA show a concordance between the spatial patterns of FA among sampling sites and the spatial distribution of sewage discharge pollutants in the Cortiou area. High developmental stress in these sampling sites is associated with exposure to high concentrations of heavy metals and many harmful organic substances contained in wastewater. FA estimated from structures with complex symmetry appears to be a fast and reliable tool to detect subtle differences in FA. Its use in biomonitoring programs for inferring anthropogenic and natural environmental stress is suggested.
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