Guillemin Marie-Laure | Universidad Austral de Chile (original) (raw)

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Papers by Guillemin Marie-Laure

Research paper thumbnail of Deep genetic divergence between austral populations of the red alga Gigartina skottsbergii reveals a cryptic species endemic to the Antarctic continent

Polar Biology

The almost complete isolation of Antarctica after the intensification the Antarctic circumpolar c... more The almost complete isolation of Antarctica after the intensification the Antarctic circumpolar current (ACC) during the middle-Miocene has been challenged by recent molecular data showing the existence of allelic exchange across the ACC. For organisms present on both sides of the ACC, two hypotheses have then been discussed to explain the origin of the Antarctic populations: (1) They correspond to recent immigrants from adjacent continents, or (2) they have evolved in situ and have survived the dramatic effects of the last Quaternary glaciations in this region. The red algae Gigartina skottsbergii presents a disjoint distribution and is reported in both Antarctica and southern South America, a distribution pattern that largely exceeds its dispersal capacity. Mitochondrial sequences of the intergenic region Cox2-3 (n = 233) and partial chloroplastic RuBisCo large subunit gene (n = 26) sequences were obtained for individuals from the Chilean sub-Antarctic ecoregion and Antarctic Peni...

Research paper thumbnail of Species replacement along a linear coastal habitat: phylogeography and speciation in the red alga Mazzaella laminarioides along the south east pacific

BMC Evolutionary Biology, 2012

Research paper thumbnail of GENETIC VARIATION IN WILD AND CULTIVATED POPULATIONS OF THE HAPLOID– DIPLOID RED ALGA GRACILARIA CHILENSIS: HOW FARMING PRACTICES FAVOR ASEXUAL REPRODUCTION AND HETEROZYGOSITY

Evolution, 2008

The extent of changes in genetic diversity and life-history traits associated with farming was in... more The extent of changes in genetic diversity and life-history traits associated with farming was investigated in the haploid-diploid red alga, Gracilaria chilensis, cultivated in Chile. This alga belongs to one of the most frequently cultivated seaweed genera around the world. Fifteen farmed populations, 11 wild populations, and two subspontaneous populations were sampled along the Chilean coast. The frequency of reproductive versus vegetative individuals and of haploid versus diploid individuals was checked in each population. In addition, the distribution of genetic variation in wild and cultivated populations was analyzed using six microsatellite markers. Our results first demonstrated that farmed populations are maintained almost exclusively by vegetative propagation. Moreover, the predominance of diploid individuals in farms showed that farming practices had significantly modified life-history traits as compared to wild populations. Second, the expected reduction in genetic diversity due to a cultivation bottleneck and subsequent clonal propagation was detected in farms. Finally, our study suggested that cultural practices in the southern part of the country contributed to the spread of selected genotypes at a local scale. Altogether, these results document for the first time that involuntary selection could operate during the first step of domestication in a marine plant.

Research paper thumbnail of DEFENSE EVOLUTION IN THE GRACILARIACEAE (RHODOPHYTA): SUBSTRATE-REGULATED OXIDATION OF AGAR OLIGOSACCHARIDES IS MORE ANCIENT THAN THE OLIGOAGAR-ACTIVATED OXIDATIVE BURST1

Journal of Phycology, 2010

Research paper thumbnail of Development of microsatellites DNA markers in the cultivated seaweed, Gracilaria chilensis (Gracilariales, Rhodophyta)

The red algae Gracilaria chilensis is extensively cultivated for agar production. In spite of its... more The red algae Gracilaria chilensis is extensively cultivated for agar production. In spite of its commercial significance as the first algal resource in Chile, no information is available on the pattern of genetic diversity. In this paper, we isolated six polymorphic microsatellite markers from a G. chilensis-enriched DNA library. Genetic diversity was assessed in two natural populations revealing relatively low levels of heterozygosity ranging from 0.00 to 0.51. The six loci developed here are good candidates to assess the level of genetic resources within this species, which probably suffered from over-exploitation in several localities along the Chilean coast.

Research paper thumbnail of Isolation of microsatellite loci from the kelp, Saccorhiza polyschides (Heterokontophyta, incertae sedis)

Kelps are ecologically important seaweeds that dominate the subtidal zones of rocky coasts. In No... more Kelps are ecologically important seaweeds that dominate the subtidal zones of rocky coasts. In Northern Europe, Saccorhiza polyschides is a pioneer species suspected of outcompeting the harvested kelp, Laminaria digitata. To examine how the process of species competition affects species distribution and genetic diversity in coastal environments, we developed 10 polymorphic microsatellite markers for S. polyschides using an enriched library (microsatellites are already available for L. digitata). These loci showed from three to 24 alleles with heterozygosities ranging from 0.36 to 0.92. This polymorphism is high enough for fine-scale population analyses including assignment tests to determine the origin of recruits.

Research paper thumbnail of Microsatellite markers in the common grey four-eyed opossum (Philander opossum: Didelphidae, Marsupialia)

Research paper thumbnail of Balancing Selection in the Wild: Testing Population Genetics Theory of Self-Incompatibility in the Rare Species Brassica insularis

Genetics, 2005

Self-incompatibility (SI) systems are widespread mechanisms that prevent self-fertilization in an... more Self-incompatibility (SI) systems are widespread mechanisms that prevent self-fertilization in angiosperms. They are generally encoded by one genome region containing several multiallelic genes, usually called the S-locus. They involve a recognition step between the pollen and the pistil component and pollen is rejected when it shares alleles with the pistil. The direct consequence is that rare alleles are favored, such that the S-alleles are subject to negative frequency-dependent selection. Several theoretical articles have predicted the specific patterns of polymorphism, compared to neutral loci, expected for such genes under balancing selection. For instance, many more alleles should be maintained and populations should be less differentiated than for neutral loci. However, empirical tests of these predictions in natural populations have remained scarce. Here, we compare the genetic structure at the S-locus and microsatellite markers for five natural populations of the rare species Brassica insularis. As in other Brassica species, B. insularis has a sporophytic SI system for which molecular markers are available. Our results match well the theoretical predictions and constitute the first general comparison of S-allele and neutral polymorphism.

Research paper thumbnail of Genetic variation in wild and cultivated populations of the haploid diploid red alga Gracilaria chilensis: How farming practices favor asexual reproduction and heterozygosity

Evolution, 2008

The extent of changes in genetic diversity and life-history traits associated with farming was in... more The extent of changes in genetic diversity and life-history traits associated with farming was investigated in the haploid-diploid red alga, Gracilaria chilensis, cultivated in Chile. This alga belongs to one of the most frequently cultivated seaweed genera around the world. Fifteen farmed populations, 11 wild populations, and two subspontaneous populations were sampled along the Chilean coast. The frequency of reproductive versus vegetative individuals and of haploid versus diploid individuals was checked in each population. In addition, the distribution of genetic variation in wild and cultivated populations was analyzed using six microsatellite markers. Our results first demonstrated that farmed populations are maintained almost exclusively by vegetative propagation. Moreover, the predominance of diploid individuals in farms showed that farming practices had significantly modified life-history traits as compared to wild populations. Second, the expected reduction in genetic diversity due to a cultivation bottleneck and subsequent clonal propagation was detected in farms. Finally, our study suggested that cultural practices in the southern part of the country contributed to the spread of selected genotypes at a local scale. Altogether, these results document for the first time that involuntary selection could operate during the first step of domestication in a marine plant.

Research paper thumbnail of Deep genetic divergence between austral populations of the red alga Gigartina skottsbergii reveals a cryptic species endemic to the Antarctic continent

Polar Biology

The almost complete isolation of Antarctica after the intensification the Antarctic circumpolar c... more The almost complete isolation of Antarctica after the intensification the Antarctic circumpolar current (ACC) during the middle-Miocene has been challenged by recent molecular data showing the existence of allelic exchange across the ACC. For organisms present on both sides of the ACC, two hypotheses have then been discussed to explain the origin of the Antarctic populations: (1) They correspond to recent immigrants from adjacent continents, or (2) they have evolved in situ and have survived the dramatic effects of the last Quaternary glaciations in this region. The red algae Gigartina skottsbergii presents a disjoint distribution and is reported in both Antarctica and southern South America, a distribution pattern that largely exceeds its dispersal capacity. Mitochondrial sequences of the intergenic region Cox2-3 (n = 233) and partial chloroplastic RuBisCo large subunit gene (n = 26) sequences were obtained for individuals from the Chilean sub-Antarctic ecoregion and Antarctic Peni...

Research paper thumbnail of Species replacement along a linear coastal habitat: phylogeography and speciation in the red alga Mazzaella laminarioides along the south east pacific

BMC Evolutionary Biology, 2012

Research paper thumbnail of GENETIC VARIATION IN WILD AND CULTIVATED POPULATIONS OF THE HAPLOID– DIPLOID RED ALGA GRACILARIA CHILENSIS: HOW FARMING PRACTICES FAVOR ASEXUAL REPRODUCTION AND HETEROZYGOSITY

Evolution, 2008

The extent of changes in genetic diversity and life-history traits associated with farming was in... more The extent of changes in genetic diversity and life-history traits associated with farming was investigated in the haploid-diploid red alga, Gracilaria chilensis, cultivated in Chile. This alga belongs to one of the most frequently cultivated seaweed genera around the world. Fifteen farmed populations, 11 wild populations, and two subspontaneous populations were sampled along the Chilean coast. The frequency of reproductive versus vegetative individuals and of haploid versus diploid individuals was checked in each population. In addition, the distribution of genetic variation in wild and cultivated populations was analyzed using six microsatellite markers. Our results first demonstrated that farmed populations are maintained almost exclusively by vegetative propagation. Moreover, the predominance of diploid individuals in farms showed that farming practices had significantly modified life-history traits as compared to wild populations. Second, the expected reduction in genetic diversity due to a cultivation bottleneck and subsequent clonal propagation was detected in farms. Finally, our study suggested that cultural practices in the southern part of the country contributed to the spread of selected genotypes at a local scale. Altogether, these results document for the first time that involuntary selection could operate during the first step of domestication in a marine plant.

Research paper thumbnail of DEFENSE EVOLUTION IN THE GRACILARIACEAE (RHODOPHYTA): SUBSTRATE-REGULATED OXIDATION OF AGAR OLIGOSACCHARIDES IS MORE ANCIENT THAN THE OLIGOAGAR-ACTIVATED OXIDATIVE BURST1

Journal of Phycology, 2010

Research paper thumbnail of Development of microsatellites DNA markers in the cultivated seaweed, Gracilaria chilensis (Gracilariales, Rhodophyta)

The red algae Gracilaria chilensis is extensively cultivated for agar production. In spite of its... more The red algae Gracilaria chilensis is extensively cultivated for agar production. In spite of its commercial significance as the first algal resource in Chile, no information is available on the pattern of genetic diversity. In this paper, we isolated six polymorphic microsatellite markers from a G. chilensis-enriched DNA library. Genetic diversity was assessed in two natural populations revealing relatively low levels of heterozygosity ranging from 0.00 to 0.51. The six loci developed here are good candidates to assess the level of genetic resources within this species, which probably suffered from over-exploitation in several localities along the Chilean coast.

Research paper thumbnail of Isolation of microsatellite loci from the kelp, Saccorhiza polyschides (Heterokontophyta, incertae sedis)

Kelps are ecologically important seaweeds that dominate the subtidal zones of rocky coasts. In No... more Kelps are ecologically important seaweeds that dominate the subtidal zones of rocky coasts. In Northern Europe, Saccorhiza polyschides is a pioneer species suspected of outcompeting the harvested kelp, Laminaria digitata. To examine how the process of species competition affects species distribution and genetic diversity in coastal environments, we developed 10 polymorphic microsatellite markers for S. polyschides using an enriched library (microsatellites are already available for L. digitata). These loci showed from three to 24 alleles with heterozygosities ranging from 0.36 to 0.92. This polymorphism is high enough for fine-scale population analyses including assignment tests to determine the origin of recruits.

Research paper thumbnail of Microsatellite markers in the common grey four-eyed opossum (Philander opossum: Didelphidae, Marsupialia)

Research paper thumbnail of Balancing Selection in the Wild: Testing Population Genetics Theory of Self-Incompatibility in the Rare Species Brassica insularis

Genetics, 2005

Self-incompatibility (SI) systems are widespread mechanisms that prevent self-fertilization in an... more Self-incompatibility (SI) systems are widespread mechanisms that prevent self-fertilization in angiosperms. They are generally encoded by one genome region containing several multiallelic genes, usually called the S-locus. They involve a recognition step between the pollen and the pistil component and pollen is rejected when it shares alleles with the pistil. The direct consequence is that rare alleles are favored, such that the S-alleles are subject to negative frequency-dependent selection. Several theoretical articles have predicted the specific patterns of polymorphism, compared to neutral loci, expected for such genes under balancing selection. For instance, many more alleles should be maintained and populations should be less differentiated than for neutral loci. However, empirical tests of these predictions in natural populations have remained scarce. Here, we compare the genetic structure at the S-locus and microsatellite markers for five natural populations of the rare species Brassica insularis. As in other Brassica species, B. insularis has a sporophytic SI system for which molecular markers are available. Our results match well the theoretical predictions and constitute the first general comparison of S-allele and neutral polymorphism.

Research paper thumbnail of Genetic variation in wild and cultivated populations of the haploid diploid red alga Gracilaria chilensis: How farming practices favor asexual reproduction and heterozygosity

Evolution, 2008

The extent of changes in genetic diversity and life-history traits associated with farming was in... more The extent of changes in genetic diversity and life-history traits associated with farming was investigated in the haploid-diploid red alga, Gracilaria chilensis, cultivated in Chile. This alga belongs to one of the most frequently cultivated seaweed genera around the world. Fifteen farmed populations, 11 wild populations, and two subspontaneous populations were sampled along the Chilean coast. The frequency of reproductive versus vegetative individuals and of haploid versus diploid individuals was checked in each population. In addition, the distribution of genetic variation in wild and cultivated populations was analyzed using six microsatellite markers. Our results first demonstrated that farmed populations are maintained almost exclusively by vegetative propagation. Moreover, the predominance of diploid individuals in farms showed that farming practices had significantly modified life-history traits as compared to wild populations. Second, the expected reduction in genetic diversity due to a cultivation bottleneck and subsequent clonal propagation was detected in farms. Finally, our study suggested that cultural practices in the southern part of the country contributed to the spread of selected genotypes at a local scale. Altogether, these results document for the first time that involuntary selection could operate during the first step of domestication in a marine plant.