Population connectivity through seed and pollen dispersal determines the genetic diversity,adaptive potential,and demography of plant metapopulations.In wind-pollinated trees,population connectivity is typically maint...Population connectivity through seed and pollen dispersal determines the genetic diversity,adaptive potential,and demography of plant metapopulations.In wind-pollinated trees,population connectivity is typically maintained by long-distance pollen flow,counteracting the genetic differentiation generated by drift and restricted seed dispersal.Although strong population fragmentation is theoretically expected to disrupt connectivity in forest trees,empirical evidence remains scarce and inconclusive.We investigated contemporary connectivity within a network of small remnant populations of a declining conifer(Taxus baccata L.),which have been hypothesized to be largely isolated from each other.We tested this hypothesis using molecular data for adult trees and naturally recruited seedlings from all known remnants across a fragmented landscape spanning a length of 20 km,and a specifically designed statistical approach to quantify contemporary pollen and seed migration rates between populations.We additionally assessed dispersal potential using a spatially explicit parentage analysis to estimate seed and pollen dispersal kernels within one of the remnants.Estimated pairwise migration rates between populations were barely detectable for seeds,while they were larger(up to 1.1%)and significant for pollen.Both seed and pollen migration rates decreased with geographic distance between populations,more steeply in the case of pollen migration.According to parentage-based dispersal kernels,51.8% of seeds and 11.4% of pollen travel less than 25 m,whereas 0.2% of seeds and 36.1%of pollen travel more than 250 m from a source tree.In addition,1.2% of pollen can travel more than 2.5 km.We showed that strong present-day population fragmentation,with separation distances over a few kilometers between small fragments,can substantially limit the connectivity of a wind-pollinated declining tree,leading to low pollen-mediated contemporary gene flow and null or virtually null demographic connectivity via seed dispersal.展开更多
Climate change,particularly extreme climate events,is likely to alter the population connectivity in diverse taxa.While the population connectivity for highly migratory species is expected to be vulnerable to climate ...Climate change,particularly extreme climate events,is likely to alter the population connectivity in diverse taxa.While the population connectivity for highly migratory species is expected to be vulnerable to climate change,the complex migration patterns has made the measurement difficult and studies rare.However,otolith biogeochemistry provides the possibility to evaluate these climate-induced impacts.Japanese Spanish mackerel Scomberomorus niphonius is a highly migratory fish that is widely distributed in the northwest Pacific.Otoliths biogeochemistry of age-1 spawning or spent individuals from three consecutive years(2016-2018),during which a very strong El Niño was experienced(2015-2016),were analyzed to evaluate the temporal variation of connectivity for S.niphonius population along the coast of China.The elemental concentrations of the whole otolith showed that Ba:Ca and Mg:Ca values were found to significantly increase in the El Niño year.The random forest classification and clustering analysis indicated a large-scale connectivity between East China Sea and the Yellow Sea in the El Niño year whereas the local S.niphonius assemblages in different spawning areas were more self-sustaining after the El Niño year.These findings lead to the hypothesis that environmental conditions associated with the El Niño Southern Oscillation(ENSO)events in the Northern Pacific Ocean would likely influence the population connectivity of S.niphonius.If so,extreme climate events can result in profound changes in the extent,pattern and connectivity of migratory fish populations.Our study demonstrates that otolith biogeochemistry could provide insight towards revealing how fish population response to extreme climate events.展开更多
The ability of the axon to form de novo collateral branches along its length is fundamental to the establishment of complex patterns of connectivity during development and is also a major response of many axonal popul...The ability of the axon to form de novo collateral branches along its length is fundamental to the establishment of complex patterns of connectivity during development and is also a major response of many axonal populations following injury.The emergence of branches is under both positive and negative control by extracellular signals.展开更多
Indo-Pacific humpback dolphins(Sousa chinensis)inhabit shallow coastal waters of the Indo-Pacific region including southeast China,with at least 6 putative populations identified to date in Chinese waters.However,the ...Indo-Pacific humpback dolphins(Sousa chinensis)inhabit shallow coastal waters of the Indo-Pacific region including southeast China,with at least 6 putative populations identified to date in Chinese waters.However,the connectivity among these populations has not yet been fully investigated.In the present study,we compared and crossmatched photographic catalogs of individual dolphins collected to date in the Pearl River Delta region,Leizhou Bay,Sanniang Bay,and waters southwest of Hainan Island,a total of 3158 individuals,and found no re-sighting of individual dolphins among the 4 study areas.Furthermore,there was a notable difference in the pigmentation pattern displayed by individuals from these 4 regions.We suggest that this may be a phenotypical expression of fine-scale regional differentiation among humpback dolphin groups,possibly distinct populations.Given the considerable conservation management implications it may carry(e.g.definition of management units),further research is much needed.展开更多
基金supported by the National Science Centre,Poland(the grant UMO-2018/31/B/NZ8/01808 to IJC).
文摘Population connectivity through seed and pollen dispersal determines the genetic diversity,adaptive potential,and demography of plant metapopulations.In wind-pollinated trees,population connectivity is typically maintained by long-distance pollen flow,counteracting the genetic differentiation generated by drift and restricted seed dispersal.Although strong population fragmentation is theoretically expected to disrupt connectivity in forest trees,empirical evidence remains scarce and inconclusive.We investigated contemporary connectivity within a network of small remnant populations of a declining conifer(Taxus baccata L.),which have been hypothesized to be largely isolated from each other.We tested this hypothesis using molecular data for adult trees and naturally recruited seedlings from all known remnants across a fragmented landscape spanning a length of 20 km,and a specifically designed statistical approach to quantify contemporary pollen and seed migration rates between populations.We additionally assessed dispersal potential using a spatially explicit parentage analysis to estimate seed and pollen dispersal kernels within one of the remnants.Estimated pairwise migration rates between populations were barely detectable for seeds,while they were larger(up to 1.1%)and significant for pollen.Both seed and pollen migration rates decreased with geographic distance between populations,more steeply in the case of pollen migration.According to parentage-based dispersal kernels,51.8% of seeds and 11.4% of pollen travel less than 25 m,whereas 0.2% of seeds and 36.1%of pollen travel more than 250 m from a source tree.In addition,1.2% of pollen can travel more than 2.5 km.We showed that strong present-day population fragmentation,with separation distances over a few kilometers between small fragments,can substantially limit the connectivity of a wind-pollinated declining tree,leading to low pollen-mediated contemporary gene flow and null or virtually null demographic connectivity via seed dispersal.
基金supported by the National Natural Science Foundation of China(NSFC)(Grant No.41930534).
文摘Climate change,particularly extreme climate events,is likely to alter the population connectivity in diverse taxa.While the population connectivity for highly migratory species is expected to be vulnerable to climate change,the complex migration patterns has made the measurement difficult and studies rare.However,otolith biogeochemistry provides the possibility to evaluate these climate-induced impacts.Japanese Spanish mackerel Scomberomorus niphonius is a highly migratory fish that is widely distributed in the northwest Pacific.Otoliths biogeochemistry of age-1 spawning or spent individuals from three consecutive years(2016-2018),during which a very strong El Niño was experienced(2015-2016),were analyzed to evaluate the temporal variation of connectivity for S.niphonius population along the coast of China.The elemental concentrations of the whole otolith showed that Ba:Ca and Mg:Ca values were found to significantly increase in the El Niño year.The random forest classification and clustering analysis indicated a large-scale connectivity between East China Sea and the Yellow Sea in the El Niño year whereas the local S.niphonius assemblages in different spawning areas were more self-sustaining after the El Niño year.These findings lead to the hypothesis that environmental conditions associated with the El Niño Southern Oscillation(ENSO)events in the Northern Pacific Ocean would likely influence the population connectivity of S.niphonius.If so,extreme climate events can result in profound changes in the extent,pattern and connectivity of migratory fish populations.Our study demonstrates that otolith biogeochemistry could provide insight towards revealing how fish population response to extreme climate events.
文摘The ability of the axon to form de novo collateral branches along its length is fundamental to the establishment of complex patterns of connectivity during development and is also a major response of many axonal populations following injury.The emergence of branches is under both positive and negative control by extracellular signals.
基金This research was financially supported by the National Natural Science Foundation of China(41406182,41306169,and 41422604)the biodiversity investigation,observation,and assessment program(2019-2023)of Ministry of Ecology and Environment of China+2 种基金Research Grants Council(RGC)of Hong Kong(General Research Fund HKU 768913M)Marine Ecology Enhancement Fund(MEEF2017015,MEEF2017015A,MEEF2017015B,and MEEF2017015C)Ocean Park Conservation Foundation Hong Kong(MM01-1415,MM02-1516,AW02-1920,AW04_1617,MM01_1920).
文摘Indo-Pacific humpback dolphins(Sousa chinensis)inhabit shallow coastal waters of the Indo-Pacific region including southeast China,with at least 6 putative populations identified to date in Chinese waters.However,the connectivity among these populations has not yet been fully investigated.In the present study,we compared and crossmatched photographic catalogs of individual dolphins collected to date in the Pearl River Delta region,Leizhou Bay,Sanniang Bay,and waters southwest of Hainan Island,a total of 3158 individuals,and found no re-sighting of individual dolphins among the 4 study areas.Furthermore,there was a notable difference in the pigmentation pattern displayed by individuals from these 4 regions.We suggest that this may be a phenotypical expression of fine-scale regional differentiation among humpback dolphin groups,possibly distinct populations.Given the considerable conservation management implications it may carry(e.g.definition of management units),further research is much needed.
