Although several methods are available to study the extent of isolation by distance （IBD） among natural populations, comparatively few exist to detect the presence of sharp genetic breaks in genetic distance dataset...Although several methods are available to study the extent of isolation by distance （IBD） among natural populations, comparatively few exist to detect the presence of sharp genetic breaks in genetic distance datasets. In recent years, Monmonier＇s maximum-difference algorithm has been increasingly used by population geneticists. However, this method does not provide means to measure the statistical significance of such barriers, nor to determine their relative contribution to population differentiation with respect to IBD. Here, we propose an approach to assess the significance of genetic boundaries. The method is based on the calculation of a multiple regression from distance matrices, where binary matrices represent putative genetic barriers to test, in addition to geographic and genetic distances. Simulation results suggest that this method reliably detects the presence of genetic barriers, even in situations where IBD is also significant. We also illustrate the methodology by analyzing previously published datasets. Conclusions about the importance of genetic barriers can be misleading if one does not take into consideration their relative contribution to the overall genetic structure of species.展开更多
Knowledge of what pest species are eating is important to determine their impact on stored food products and to plan management strategies accordingly.In this study,we investigated the food habits of 2 rodents,Rattus ...Knowledge of what pest species are eating is important to determine their impact on stored food products and to plan management strategies accordingly.In this study,we investigated the food habits of 2 rodents,Rattus rattus(ship rat)and Mus musculus castaneus(house mouse)as well as an insectivore,Suncus murinus(shrew),present in human dwellings.Both a microhistological approach and a DNA barcoding approach were used in the present study.Following DNA extraction,amplification was performed using group-specific primers targeting birds,plants and invertebrates.Resulting polymerase chain reaction products were sequenced and analyzed to identify the different prey species present in the gut contents.The findings from the application of both techniques were in agreement,but the detection of prey type with each technique was different.The DNA barcoding approach gave greater species-level identification when compared to the microhistological method,especially for the invertebrate and avian prey.Overall,with both techniques,23 prey taxa were identified in the gut contents of the 3 species,including 15 plants,7 insects and a single bird species.We conclude that with a selection of suitable“barcode genes”and optimization of polymerase chain reaction protocols,DNA barcoding can provide more accurate and faster results.Prey detection from either technique alone can bias the dietary information.Hence,combining prey information of both microhistological analysis and DNA barcoding is recommended to study pest diet,especially if the pest is an omnivore or insectivore species.展开更多
During the summer months,Adélie penguins represent the dominant biomass of terrestrial Antarctica.Literally millions of individuals nest in ice-free areas around the coast of the continent.Hence,these modern popu...During the summer months,Adélie penguins represent the dominant biomass of terrestrial Antarctica.Literally millions of individuals nest in ice-free areas around the coast of the continent.Hence,these modern populations of Adélie penguins have often been championed as an ideal biological indicator of ecological and environmental changes that we currently face.In addition,Adélie penguins show an extraordinary record of sub-fossil remains,dating back to the late Pleistocene.At this time,temperatures were much lower than now.Hence,this species offers unique long-term information,at both the genomic and ecological levels,about how a species has responded to climate change over more than 40000 years.展开更多
基金supported by a Natural Sciences and Engineering Research Council of Canada scholarship and a Fonds Québécois de la Recherche sur la Nature et les Technologies scholarship to S.R.P.a Natural Sciences and Engineering Research Council of Canada grant to F.-J.L.
文摘Although several methods are available to study the extent of isolation by distance （IBD） among natural populations, comparatively few exist to detect the presence of sharp genetic breaks in genetic distance datasets. In recent years, Monmonier＇s maximum-difference algorithm has been increasingly used by population geneticists. However, this method does not provide means to measure the statistical significance of such barriers, nor to determine their relative contribution to population differentiation with respect to IBD. Here, we propose an approach to assess the significance of genetic boundaries. The method is based on the calculation of a multiple regression from distance matrices, where binary matrices represent putative genetic barriers to test, in addition to geographic and genetic distances. Simulation results suggest that this method reliably detects the presence of genetic barriers, even in situations where IBD is also significant. We also illustrate the methodology by analyzing previously published datasets. Conclusions about the importance of genetic barriers can be misleading if one does not take into consideration their relative contribution to the overall genetic structure of species.
文摘Knowledge of what pest species are eating is important to determine their impact on stored food products and to plan management strategies accordingly.In this study,we investigated the food habits of 2 rodents,Rattus rattus(ship rat)and Mus musculus castaneus(house mouse)as well as an insectivore,Suncus murinus(shrew),present in human dwellings.Both a microhistological approach and a DNA barcoding approach were used in the present study.Following DNA extraction,amplification was performed using group-specific primers targeting birds,plants and invertebrates.Resulting polymerase chain reaction products were sequenced and analyzed to identify the different prey species present in the gut contents.The findings from the application of both techniques were in agreement,but the detection of prey type with each technique was different.The DNA barcoding approach gave greater species-level identification when compared to the microhistological method,especially for the invertebrate and avian prey.Overall,with both techniques,23 prey taxa were identified in the gut contents of the 3 species,including 15 plants,7 insects and a single bird species.We conclude that with a selection of suitable“barcode genes”and optimization of polymerase chain reaction protocols,DNA barcoding can provide more accurate and faster results.Prey detection from either technique alone can bias the dietary information.Hence,combining prey information of both microhistological analysis and DNA barcoding is recommended to study pest diet,especially if the pest is an omnivore or insectivore species.
文摘During the summer months,Adélie penguins represent the dominant biomass of terrestrial Antarctica.Literally millions of individuals nest in ice-free areas around the coast of the continent.Hence,these modern populations of Adélie penguins have often been championed as an ideal biological indicator of ecological and environmental changes that we currently face.In addition,Adélie penguins show an extraordinary record of sub-fossil remains,dating back to the late Pleistocene.At this time,temperatures were much lower than now.Hence,this species offers unique long-term information,at both the genomic and ecological levels,about how a species has responded to climate change over more than 40000 years.
