Suchergebnisse

The European catfish, Silurus glanis, was widely introduced in western Europe, and it has now established self-sustaining populations in numerous large rivers of western France. Using data collected from surveys conducted by the French National Agency for Water and Aquatic Environment (Onema) from 1989 to 2010 in more than 500 sites throughout the country (10636 electrofishing surveys), we investigated the potential impact of the European catfish on fish communities in French rivers. In the first part of the analysis, we compared trends observed before and after the European catfish was established at given sites (before-after analysis). Species richness, evenness and diversity decreased significantly after the European catfish was established at 1.4%, 1.4% and 5.8% of the sites, respectively. Total fish biomass and density decreased significantly at 6.6% and 2.9% of the sites, respectively. In the second part of the analysis, we compared sites with European catfish against sites lacking European catfish during the same period (with-without analysis). Fish species richness was significantly higher in sites with European catfish. No significant differences in fish diversity, evenness, total fish biomass or density were found between sites with or without European catfish. While our results indicate that the European catfish may in a few cases impact fish communities or populations, it does not appear to be responsible for a countrywide collapse in fish assemblages.

International audience ; The European catfish, Silurus glanis, was widely introduced in western Europe, and it has now established self-sustaining populations in numerous large rivers of western France. Using data collected from surveys conducted by the French National Agency for Water and Aquatic Environment (Onema) from 1989 to 2010 in more than 500 sites throughout the country (10636 electrofishing surveys), we investigated the potential impact of the European catfish on fish communities in French rivers. In the first part of the analysis, we compared trends observed before and after the European catfish was established at given sites (before-after analysis). Species richness, evenness and diversity decreased significantly after the European catfish was established at 1.4%, 1.4% and 5.8% of the sites, respectively. Total fish biomass and density decreased significantly at 6.6% and 2.9% of the sites, respectively. In the second part of the analysis, we compared sites with European catfish against sites lacking European catfish during the same period (with-without analysis). Fish species richness was significantly higher in sites with European catfish. No significant differences in fish diversity, evenness, total fish biomass or density were found between sites with or without European catfish. While our results indicate that the European catfish may in a few cases impact fish communities or populations, it does not appear to be responsible for a countrywide collapse in fish assemblages.

International audience ; The European catfish, Silurus glanis, was widely introduced in western Europe, and it has now established self-sustaining populations in numerous large rivers of western France. Using data collected from surveys conducted by the French National Agency for Water and Aquatic Environment (Onema) from 1989 to 2010 in more than 500 sites throughout the country (10636 electrofishing surveys), we investigated the potential impact of the European catfish on fish communities in French rivers. In the first part of the analysis, we compared trends observed before and after the European catfish was established at given sites (before-after analysis). Species richness, evenness and diversity decreased significantly after the European catfish was established at 1.4%, 1.4% and 5.8% of the sites, respectively. Total fish biomass and density decreased significantly at 6.6% and 2.9% of the sites, respectively. In the second part of the analysis, we compared sites with European catfish against sites lacking European catfish during the same period (with-without analysis). Fish species richness was significantly higher in sites with European catfish. No significant differences in fish diversity, evenness, total fish biomass or density were found between sites with or without European catfish. While our results indicate that the European catfish may in a few cases impact fish communities or populations, it does not appear to be responsible for a countrywide collapse in fish assemblages.

International audience ; The European catfish, Silurus glanis, was widely introduced in western Europe, and it has now established self-sustaining populations in numerous large rivers of western France. Using data collected from surveys conducted by the French National Agency for Water and Aquatic Environment (Onema) from 1989 to 2010 in more than 500 sites throughout the country (10636 electrofishing surveys), we investigated the potential impact of the European catfish on fish communities in French rivers. In the first part of the analysis, we compared trends observed before and after the European catfish was established at given sites (before-after analysis). Species richness, evenness and diversity decreased significantly after the European catfish was established at 1.4%, 1.4% and 5.8% of the sites, respectively. Total fish biomass and density decreased significantly at 6.6% and 2.9% of the sites, respectively. In the second part of the analysis, we compared sites with European catfish against sites lacking European catfish during the same period (with-without analysis). Fish species richness was significantly higher in sites with European catfish. No significant differences in fish diversity, evenness, total fish biomass or density were found between sites with or without European catfish. While our results indicate that the European catfish may in a few cases impact fish communities or populations, it does not appear to be responsible for a countrywide collapse in fish assemblages.

Lorsqu'une espèce exotique envahissante a débuté son extension dans sa région d'accueil, il est souvent impossible de l'éradiquer. Même son confinement et la limitation de ses effectifs restent des opérations excessivement compliquées, coûteuses et souvent dommageables pour le milieu naturel. C'est pourquoi il est nécessaire de mettre l'accent sur la prévention pour lutter contre les invasions futures. L'établissement de listes d'espèces hiérarchisées comportant, pour un certain nombre d'espèces, des mesures restrictives (" listes noires ") demeure un premier pas important en matière d'amélioration des dispositifs réglementaires actuels et de mise en place d'une stratégie de prévention contre les espèces invasives. En parallèle, des démarches volontaires et participatives peuvent être lancées comme c'est déjà le cas depuis plusieurs années dans certains secteurs. Enfin, la mise en place de réseaux de veille est indispensable, du fait de l'impossibilité actuelle de connaitre les espèces qui entrent chaque année sur le territoire français. Ces réseaux doivent non seulement permettre la détection précoce des nouvelles espèces établies, mais aussi faciliter la mise en ½uvre des mesures de gestion adéquates (réponse rapide), à un coût plus soutenable que la lutte classique. Pour qu'ils soient pleinement opérationnels, il est nécessaire de cibler les zones de détection précoce, et développer des outils spécifiques. Cette nouvelle stratégie implique aussi de mieux identifier et former les acteurs qui la feront vivre. / It is quite difficult to eradicate an invasive alien species when it has already begun to spread. Even containment is very complicated, expensive andmay be harmful for natural ecosystems. For these reasons, it is necessary to improve prevention in order to foresee future invasions. The creation of a national list prioritized by negative impacts and specifying restrictivemeasures (black list) would be a consistent progress for the enhancement of actual legislation and the nation could take a step forward ...

Lorsqu'une espèce exotique envahissante a débuté son extension dans sa région d'accueil, il est souvent impossible de l'éradiquer. Même son confinement et la limitation de ses effectifs restent des opérations excessivement compliquées, coûteuses et souvent dommageables pour le milieu naturel. C'est pourquoi il est nécessaire de mettre l'accent sur la prévention pour lutter contre les invasions futures. L'établissement de listes d'espèces hiérarchisées comportant, pour un certain nombre d'espèces, des mesures restrictives (" listes noires ") demeure un premier pas important en matière d'amélioration des dispositifs réglementaires actuels et de mise en place d'une stratégie de prévention contre les espèces invasives. En parallèle, des démarches volontaires et participatives peuvent être lancées comme c'est déjà le cas depuis plusieurs années dans certains secteurs. Enfin, la mise en place de réseaux de veille est indispensable, du fait de l'impossibilité actuelle de connaitre les espèces qui entrent chaque année sur le territoire français. Ces réseaux doivent non seulement permettre la détection précoce des nouvelles espèces établies, mais aussi faciliter la mise en ½uvre des mesures de gestion adéquates (réponse rapide), à un coût plus soutenable que la lutte classique. Pour qu'ils soient pleinement opérationnels, il est nécessaire de cibler les zones de détection précoce, et développer des outils spécifiques. Cette nouvelle stratégie implique aussi de mieux identifier et former les acteurs qui la feront vivre. / It is quite difficult to eradicate an invasive alien species when it has already begun to spread. Even containment is very complicated, expensive andmay be harmful for natural ecosystems. For these reasons, it is necessary to improve prevention in order to foresee future invasions. The creation of a national list prioritized by negative impacts and specifying restrictivemeasures (black list) would be a consistent progress for the enhancement of actual legislation and the nation could take a step forward ...

Lorsqu'une espèce exotique envahissante a débuté son extension dans sa région d'accueil, il est souvent impossible de l'éradiquer. Même son confinement et la limitation de ses effectifs restent des opérations excessivement compliquées, coûteuses et souvent dommageables pour le milieu naturel. C'est pourquoi il est nécessaire de mettre l'accent sur la prévention pour lutter contre les invasions futures. L'établissement de listes d'espèces hiérarchisées comportant, pour un certain nombre d'espèces, des mesures restrictives (" listes noires ") demeure un premier pas important en matière d'amélioration des dispositifs réglementaires actuels et de mise en place d'une stratégie de prévention contre les espèces invasives. En parallèle, des démarches volontaires et participatives peuvent être lancées comme c'est déjà le cas depuis plusieurs années dans certains secteurs. Enfin, la mise en place de réseaux de veille est indispensable, du fait de l'impossibilité actuelle de connaitre les espèces qui entrent chaque année sur le territoire français. Ces réseaux doivent non seulement permettre la détection précoce des nouvelles espèces établies, mais aussi faciliter la mise en ½uvre des mesures de gestion adéquates (réponse rapide), à un coût plus soutenable que la lutte classique. Pour qu'ils soient pleinement opérationnels, il est nécessaire de cibler les zones de détection précoce, et développer des outils spécifiques. Cette nouvelle stratégie implique aussi de mieux identifier et former les acteurs qui la feront vivre. / It is quite difficult to eradicate an invasive alien species when it has already begun to spread. Even containment is very complicated, expensive andmay be harmful for natural ecosystems. For these reasons, it is necessary to improve prevention in order to foresee future invasions. The creation of a national list prioritized by negative impacts and specifying restrictivemeasures (black list) would be a consistent progress for the enhancement of actual legislation and the nation could take a step forward ...

Lorsqu'une espèce exotique envahissante a débuté son extension dans sa région d'accueil, il est souvent impossible de l'éradiquer. Même son confinement et la limitation de ses effectifs restent des opérations excessivement compliquées, coûteuses et souvent dommageables pour le milieu naturel. C'est pourquoi il est nécessaire de mettre l'accent sur la prévention pour lutter contre les invasions futures. L'établissement de listes d'espèces hiérarchisées comportant, pour un certain nombre d'espèces, des mesures restrictives (" listes noires ") demeure un premier pas important en matière d'amélioration des dispositifs réglementaires actuels et de mise en place d'une stratégie de prévention contre les espèces invasives. En parallèle, des démarches volontaires et participatives peuvent être lancées comme c'est déjà le cas depuis plusieurs années dans certains secteurs. Enfin, la mise en place de réseaux de veille est indispensable, du fait de l'impossibilité actuelle de connaitre les espèces qui entrent chaque année sur le territoire français. Ces réseaux doivent non seulement permettre la détection précoce des nouvelles espèces établies, mais aussi faciliter la mise en ½uvre des mesures de gestion adéquates (réponse rapide), à un coût plus soutenable que la lutte classique. Pour qu'ils soient pleinement opérationnels, il est nécessaire de cibler les zones de détection précoce, et développer des outils spécifiques. Cette nouvelle stratégie implique aussi de mieux identifier et former les acteurs qui la feront vivre. / It is quite difficult to eradicate an invasive alien species when it has already begun to spread. Even containment is very complicated, expensive andmay be harmful for natural ecosystems. For these reasons, it is necessary to improve prevention in order to foresee future invasions. The creation of a national list prioritized by negative impacts and specifying restrictivemeasures (black list) would be a consistent progress for the enhancement of actual legislation and the nation could take a step forward ...

Lorsqu'une espèce exotique envahissante a débuté son extension dans sa région d'accueil, il est souvent impossible de l'éradiquer. Même son confinement et la limitation de ses effectifs restent des opérations excessivement compliquées, coûteuses et souvent dommageables pour le milieu naturel. C'est pourquoi il est nécessaire de mettre l'accent sur la prévention pour lutter contre les invasions futures. L'établissement de listes d'espèces hiérarchisées comportant, pour un certain nombre d'espèces, des mesures restrictives (" listes noires ") demeure un premier pas important en matière d'amélioration des dispositifs réglementaires actuels et de mise en place d'une stratégie de prévention contre les espèces invasives. En parallèle, des démarches volontaires et participatives peuvent être lancées comme c'est déjà le cas depuis plusieurs années dans certains secteurs. Enfin, la mise en place de réseaux de veille est indispensable, du fait de l'impossibilité actuelle de connaitre les espèces qui entrent chaque année sur le territoire français. Ces réseaux doivent non seulement permettre la détection précoce des nouvelles espèces établies, mais aussi faciliter la mise en ½uvre des mesures de gestion adéquates (réponse rapide), à un coût plus soutenable que la lutte classique. Pour qu'ils soient pleinement opérationnels, il est nécessaire de cibler les zones de détection précoce, et développer des outils spécifiques. Cette nouvelle stratégie implique aussi de mieux identifier et former les acteurs qui la feront vivre. / It is quite difficult to eradicate an invasive alien species when it has already begun to spread. Even containment is very complicated, expensive andmay be harmful for natural ecosystems. For these reasons, it is necessary to improve prevention in order to foresee future invasions. The creation of a national list prioritized by negative impacts and specifying restrictivemeasures (black list) would be a consistent progress for the enhancement of actual legislation and the nation could take a step forward on the way to prevention. In the same way, voluntary approaches and participative initiatives can be developed as it is already done for several years with different stakeholders. Finally, because of the unfeasibility tomaster the knowledge of incoming species, setting up surveillance networks is essential. These networks are useful for a better detection of newly established species, but they alsomust facilitate rapid responses to control incipient populations of undesirable invaders. With the purpose of driving these networks to optimization, early detection areas have to be targeted and specific toolsmust be developed. This new strategy also involves a better targeting and training of the stakeholders that willmake it become alive.

International audience ; High-frequency microsatellite haplotypes of the male-specific Y-chromosome can signal past episodes of high reproductive success of particular men and their patrilineal descendants. Previously, two examples of such successful Y-lineages have been described in Asia, both associated with Altaic-speaking pastoral nomadic societies, and putatively linked to dynasties descending, respectively, from Genghis Khan and Giocangga. Here we surveyed a total of 5321 Y-chromosomes from 127 Asian populations, including novel Y-SNP and microsatellite data on 461 Central Asian males, to ask whether additional lineage expansions could be identified. Based on the most frequent eight-microsatellite haplotypes, we objectively defined 11 descent clusters (DCs), each within a specific haplogroup, that represent likely past instances of high male reproductive success, including the two previously identified cases. Analysis of the geographical patterns and ages of these DCs and their associated cultural characteristics showed that the most successful lineages are found both among sedentary agriculturalists and pastoral nomads, and expanded between 2100 BCE and 1100 CE. However, those with recent origins in the historical period are almost exclusively found in Altaic-speaking pastoral nomadic populations, which may reflect a shift in political organisation in pastoralist economies and a greater ease of transmission of Y-chromosomes through time and space facilitated by the use of horses.

International audience ; High-frequency microsatellite haplotypes of the male-specific Y-chromosome can signal past episodes of high reproductive success of particular men and their patrilineal descendants. Previously, two examples of such successful Y-lineages have been described in Asia, both associated with Altaic-speaking pastoral nomadic societies, and putatively linked to dynasties descending, respectively, from Genghis Khan and Giocangga. Here we surveyed a total of 5321 Y-chromosomes from 127 Asian populations, including novel Y-SNP and microsatellite data on 461 Central Asian males, to ask whether additional lineage expansions could be identified. Based on the most frequent eight-microsatellite haplotypes, we objectively defined 11 descent clusters (DCs), each within a specific haplogroup, that represent likely past instances of high male reproductive success, including the two previously identified cases. Analysis of the geographical patterns and ages of these DCs and their associated cultural characteristics showed that the most successful lineages are found both among sedentary agriculturalists and pastoral nomads, and expanded between 2100 BCE and 1100 CE. However, those with recent origins in the historical period are almost exclusively found in Altaic-speaking pastoral nomadic populations, which may reflect a shift in political organisation in pastoralist economies and a greater ease of transmission of Y-chromosomes through time and space facilitated by the use of horses.

International audience ; High-frequency microsatellite haplotypes of the male-specific Y-chromosome can signal past episodes of high reproductive success of particular men and their patrilineal descendants. Previously, two examples of such successful Y-lineages have been described in Asia, both associated with Altaic-speaking pastoral nomadic societies, and putatively linked to dynasties descending, respectively, from Genghis Khan and Giocangga. Here we surveyed a total of 5321 Y-chromosomes from 127 Asian populations, including novel Y-SNP and microsatellite data on 461 Central Asian males, to ask whether additional lineage expansions could be identified. Based on the most frequent eight-microsatellite haplotypes, we objectively defined 11 descent clusters (DCs), each within a specific haplogroup, that represent likely past instances of high male reproductive success, including the two previously identified cases. Analysis of the geographical patterns and ages of these DCs and their associated cultural characteristics showed that the most successful lineages are found both among sedentary agriculturalists and pastoral nomads, and expanded between 2100 BCE and 1100 CE. However, those with recent origins in the historical period are almost exclusively found in Altaic-speaking pastoral nomadic populations, which may reflect a shift in political organisation in pastoralist economies and a greater ease of transmission of Y-chromosomes through time and space facilitated by the use of horses.

International audience ; High-frequency microsatellite haplotypes of the male-specific Y-chromosome can signal past episodes of high reproductive success of particular men and their patrilineal descendants. Previously, two examples of such successful Y-lineages have been described in Asia, both associated with Altaic-speaking pastoral nomadic societies, and putatively linked to dynasties descending, respectively, from Genghis Khan and Giocangga. Here we surveyed a total of 5321 Y-chromosomes from 127 Asian populations, including novel Y-SNP and microsatellite data on 461 Central Asian males, to ask whether additional lineage expansions could be identified. Based on the most frequent eight-microsatellite haplotypes, we objectively defined 11 descent clusters (DCs), each within a specific haplogroup, that represent likely past instances of high male reproductive success, including the two previously identified cases. Analysis of the geographical patterns and ages of these DCs and their associated cultural characteristics showed that the most successful lineages are found both among sedentary agriculturalists and pastoral nomads, and expanded between 2100 BCE and 1100 CE. However, those with recent origins in the historical period are almost exclusively found in Altaic-speaking pastoral nomadic populations, which may reflect a shift in political organisation in pastoralist economies and a greater ease of transmission of Y-chromosomes through time and space facilitated by the use of horses.

High-frequency microsatellite haplotypes of the male-specific Y-chromosome can signal past episodes of high reproductive success of particular men and their patrilineal descendants. Previously, two examples of such successful Y-lineages have been described in Asia, both associated with Altaic-speaking pastoral nomadic societies, and putatively linked to dynasties descending, respectively, from Genghis Khan and Giocangga. Here we surveyed a total of 5321 Y-chromosomes from 127 Asian populations, including novel Y-SNP and microsatellite data on 461 Central Asian males, to ask whether additional lineage expansions could be identified. Based on the most frequent eight-microsatellite haplotypes, we objectively defined 11 descent clusters (DCs), each within a specific haplogroup, that represent likely past instances of high male reproductive success, including the two previously identified cases. Analysis of the geographical patterns and ages of these DCs and their associated cultural characteristics showed that the most successful lineages are found both among sedentary agriculturalists and pastoral nomads, and expanded between 2100 BCE and 1100 CE. However, those with recent origins in the historical period are almost exclusively found in Altaic-speaking pastoral nomadic populations, which may reflect a shift in political organisation in pastoralist economies and a greater ease of transmission of Y-chromosomes through time and space facilitated by the use of horses.

International audience ; High-frequency microsatellite haplotypes of the male-specific Y-chromosome can signal past episodes of high reproductive success of particular men and their patrilineal descendants. Previously, two examples of such successful Y-lineages have been described in Asia, both associated with Altaic-speaking pastoral nomadic societies, and putatively linked to dynasties descending, respectively, from Genghis Khan and Giocangga. Here we surveyed a total of 5321 Y-chromosomes from 127 Asian populations, including novel Y-SNP and microsatellite data on 461 Central Asian males, to ask whether additional lineage expansions could be identified. Based on the most frequent eight-microsatellite haplotypes, we objectively defined 11 descent clusters (DCs), each within a specific haplogroup, that represent likely past instances of high male reproductive success, including the two previously identified cases. Analysis of the geographical patterns and ages of these DCs and their associated cultural characteristics showed that the most successful lineages are found both among sedentary agriculturalists and pastoral nomads, and expanded between 2100 BCE and 1100 CE. However, those with recent origins in the historical period are almost exclusively found in Altaic-speaking pastoral nomadic populations, which may reflect a shift in political organisation in pastoralist economies and a greater ease of transmission of Y-chromosomes through time and space facilitated by the use of horses.