Many genes associated with reproduction show rapid evolution across diverse animal groups, a result commonly due to adaptive evolution driven by positive selection （Swanson and Vacquier, 2002）. Different theories ha...Many genes associated with reproduction show rapid evolution across diverse animal groups, a result commonly due to adaptive evolution driven by positive selection （Swanson and Vacquier, 2002）. Different theories have been proposed to explain the elevated rates of evolution （Swanson and Vacquier, 2002）, including sperm competition, where sperm compete to fertilize eggs leading to the proteins in the sper- matozoa adaptively evolving to increase their ability to fertilize eggs; sexual conflict, where the egg experiences a loss of fitness when sperm are too abundant; sexual selection, where eggs bind sperm carrying adaptive alleles （Palumbi, 1999）; and cryptic female choice （reviewed in Swanson and Vacquier, 2002）.展开更多
Aims As an exotic species colonises a new continent,it must overcome enormous environmental variation in its introduced range.Local adaptation of introduced species has frequently been observed at the continent scale,...Aims As an exotic species colonises a new continent,it must overcome enormous environmental variation in its introduced range.Local adaptation of introduced species has frequently been observed at the continent scale,particularly in response to latitudinal climatic variation.However,significant environmental heterogeneity can also exist at the landscape scale.A small number of studies have provided evidence that introduced species may also be capable of phenotypic and genetic differentiation at much smaller spatial scales.For example,previously we found US agricultural and non-agricultural populations of Sorghum halepense(Johnsongrass)to be phenotypically and genetically distinct.in this study,we inves-tigated whether this phenotypic differentiation of agricultural and non-agricultural populations of S.halepense is the result of fine-scale local specialisation.Methods We surveyed a nationally collected S.halepense germplasm panel and also collected neighbouring agricultural and non-agricultural sub-populations of S.halepense at four sites throughout Western Virginia,USA,raising seedlings in common conditions mimicking both agricultural and non-agricultural habitats.Important Findings At the national scale,we found evidence of habitat differentiation but not specialisation.However,at the local scale,we found evi-dence of specialisation in two of the four local populations to non-agricultural habitat,but no evidence of specialisation to agricultural habitat.These results show that local specialisation is a possible,but not guaranteed consequence of kilometre-scale habitat heterogen-eity in invasive species.This finding contributes to a growing aware-ness of the importance of fine-scale local adaptation in the ecology and management of introduced and weedy species.展开更多
Aims Germination is the earliest life-history transition of a plant species.It determines the ecological breadth and geographic ranges of a species and has major effects on its invasion potential.The largest spread of...Aims Germination is the earliest life-history transition of a plant species.It determines the ecological breadth and geographic ranges of a species and has major effects on its invasion potential.The largest spread of the invasive salt-marsh cordgrass Spartina alterniflora in China,where it extends to latitudes lower than its native range in North America,provides an opportunity to examine germination trait variation across latitudes within and among its invasive and native ranges.Methods We studied seed germination traits of S.alterniflora using seeds collected from 10 locations across latitudes in its invasive range(China,20°–40°N)and 16 locations across latitudes in its native range(USA,27°–43°N)in growth chambers with 0 PSU sterilized distilled water.We further evaluated how climate and tide range in the original locations influenced germination traits.Important Findings Native populations showed higher(~10%)germination percentage and significantly higher(~20%)germination index than invasive populations did,but invasive populations germinated significantly earlier(~3 days)than native populations.Germination percentage and germination index increased with latitude in the invasive range but decreased with latitude in the native range.The mean germination time decreased with latitude in the invasive range and paralleled that in the native range.Germination percentage and germination index were negatively correlated with mean daily temperature(Tmean),mean daily maximum temperature(Tmax)and mean daily minimum temperature(Tmin),and inversely correlated with Tmean,Tmax and Tmin in the native range.However,the mean germination time was positively correlated with Tmean,Tmax and Tmean in both ranges.Our results demonstrate that invasive and native populations have evolved different latitudinal clines in germination percentage and index,but the mean germination time of the invasive population mirrored the latitudinal cline observed in the native range,suggesting that germination strategy across latitudes may change during invasion process.展开更多
基金supported by the grant from the National Natural Science Foundation of China(No.31061160189)
文摘Many genes associated with reproduction show rapid evolution across diverse animal groups, a result commonly due to adaptive evolution driven by positive selection （Swanson and Vacquier, 2002）. Different theories have been proposed to explain the elevated rates of evolution （Swanson and Vacquier, 2002）, including sperm competition, where sperm compete to fertilize eggs leading to the proteins in the sper- matozoa adaptively evolving to increase their ability to fertilize eggs; sexual conflict, where the egg experiences a loss of fitness when sperm are too abundant; sexual selection, where eggs bind sperm carrying adaptive alleles （Palumbi, 1999）; and cryptic female choice （reviewed in Swanson and Vacquier, 2002）.
文摘Aims As an exotic species colonises a new continent,it must overcome enormous environmental variation in its introduced range.Local adaptation of introduced species has frequently been observed at the continent scale,particularly in response to latitudinal climatic variation.However,significant environmental heterogeneity can also exist at the landscape scale.A small number of studies have provided evidence that introduced species may also be capable of phenotypic and genetic differentiation at much smaller spatial scales.For example,previously we found US agricultural and non-agricultural populations of Sorghum halepense(Johnsongrass)to be phenotypically and genetically distinct.in this study,we inves-tigated whether this phenotypic differentiation of agricultural and non-agricultural populations of S.halepense is the result of fine-scale local specialisation.Methods We surveyed a nationally collected S.halepense germplasm panel and also collected neighbouring agricultural and non-agricultural sub-populations of S.halepense at four sites throughout Western Virginia,USA,raising seedlings in common conditions mimicking both agricultural and non-agricultural habitats.Important Findings At the national scale,we found evidence of habitat differentiation but not specialisation.However,at the local scale,we found evi-dence of specialisation in two of the four local populations to non-agricultural habitat,but no evidence of specialisation to agricultural habitat.These results show that local specialisation is a possible,but not guaranteed consequence of kilometre-scale habitat heterogen-eity in invasive species.This finding contributes to a growing aware-ness of the importance of fine-scale local adaptation in the ecology and management of introduced and weedy species.
基金the National Natural Science Foundation of China(31770464,31470485,41276078,32001234)China Postdoctoral Science Foundation(2019M662239,2020T130363).
文摘Aims Germination is the earliest life-history transition of a plant species.It determines the ecological breadth and geographic ranges of a species and has major effects on its invasion potential.The largest spread of the invasive salt-marsh cordgrass Spartina alterniflora in China,where it extends to latitudes lower than its native range in North America,provides an opportunity to examine germination trait variation across latitudes within and among its invasive and native ranges.Methods We studied seed germination traits of S.alterniflora using seeds collected from 10 locations across latitudes in its invasive range(China,20°–40°N)and 16 locations across latitudes in its native range(USA,27°–43°N)in growth chambers with 0 PSU sterilized distilled water.We further evaluated how climate and tide range in the original locations influenced germination traits.Important Findings Native populations showed higher(~10%)germination percentage and significantly higher(~20%)germination index than invasive populations did,but invasive populations germinated significantly earlier(~3 days)than native populations.Germination percentage and germination index increased with latitude in the invasive range but decreased with latitude in the native range.The mean germination time decreased with latitude in the invasive range and paralleled that in the native range.Germination percentage and germination index were negatively correlated with mean daily temperature(Tmean),mean daily maximum temperature(Tmax)and mean daily minimum temperature(Tmin),and inversely correlated with Tmean,Tmax and Tmin in the native range.However,the mean germination time was positively correlated with Tmean,Tmax and Tmean in both ranges.Our results demonstrate that invasive and native populations have evolved different latitudinal clines in germination percentage and index,but the mean germination time of the invasive population mirrored the latitudinal cline observed in the native range,suggesting that germination strategy across latitudes may change during invasion process.
