Globally,the threat of endangerment and extinction of small cetaceans was highlighted after the recent extinction of the Chinese River dolphin or Baiji(Lipotes vexillifer).Species with a small population size and a li...Globally,the threat of endangerment and extinction of small cetaceans was highlighted after the recent extinction of the Chinese River dolphin or Baiji(Lipotes vexillifer).Species with a small population size and a limited geographic range,such as Ganges River dolphins(GRD),are more vulnerable to extinction.The social and behavioral needs of cetaceans have been identified as potential factors increasing their vulnerability to human disturbance.However,little is known about how GRD adapt their behaviors and diel activity patterns to spatiotemporal variation.In this paper,we examined the underwater behavior of GRDs in Nepal by collecting echolocation clicks from three spatially stratified habitats in the Sapta Koshi River system over a six-month period.Our research found that GRDs behave differently in response to spatial heterogeneity,indicating diverse environmental requirements for GRD persistence.Behavioral activity and duration varied across habitats but not across time of day,suggesting that GRD behaviors are likely to be regulated by habitat structure regardless of the time of day.However,GRD consistently exhibited nocturnal activity peaks even when diurnal activity varied substantially.This indicates that river dolphins may favor nocturnal refuges as a reaction to human disturbance in highly regulated rivers.Managing human disturbances in conjunction with habitat heterogeneity can improve the persistence of riverine cetaceans.Here,we document behavioral and ecological information pertaining to GRD,which is essential to the formation of river dolphin recovery plans that link ecological perspectives to planning and management.展开更多
mt DNA 16 S r RNA基因序列分析支持将现生淡水豚 4个属归入不同的科 ,即白暨豚科(L ipotiidae)、恒河豚科 (Platanistidae)、亚河豚科 (Iniidae)和弗西豚科 (Pontoporidae) .基于邻接法的系统发生分析显示淡水豚类由白暨豚 +恒河豚和...mt DNA 16 S r RNA基因序列分析支持将现生淡水豚 4个属归入不同的科 ,即白暨豚科(L ipotiidae)、恒河豚科 (Platanistidae)、亚河豚科 (Iniidae)和弗西豚科 (Pontoporidae) .基于邻接法的系统发生分析显示淡水豚类由白暨豚 +恒河豚和弗西豚 +亚河豚两个单系组成 ,但两个单系之间并无姊妹关系 .淡水豚类是并系的 .16 S r RNA基因的系统发生树与 mt DNA细胞色素 b基因和12 S r RNA基因的系统发生树并不完全一致 .这种差异一方面可能反映了不同的基因树间的差异 ,但也可能与本文分析的 16 S r RNA基因片段中变异位点数和简约信息位点数较少有关 .因此 ,有必要增加序列长度来进一步验证 .展开更多
文摘Globally,the threat of endangerment and extinction of small cetaceans was highlighted after the recent extinction of the Chinese River dolphin or Baiji(Lipotes vexillifer).Species with a small population size and a limited geographic range,such as Ganges River dolphins(GRD),are more vulnerable to extinction.The social and behavioral needs of cetaceans have been identified as potential factors increasing their vulnerability to human disturbance.However,little is known about how GRD adapt their behaviors and diel activity patterns to spatiotemporal variation.In this paper,we examined the underwater behavior of GRDs in Nepal by collecting echolocation clicks from three spatially stratified habitats in the Sapta Koshi River system over a six-month period.Our research found that GRDs behave differently in response to spatial heterogeneity,indicating diverse environmental requirements for GRD persistence.Behavioral activity and duration varied across habitats but not across time of day,suggesting that GRD behaviors are likely to be regulated by habitat structure regardless of the time of day.However,GRD consistently exhibited nocturnal activity peaks even when diurnal activity varied substantially.This indicates that river dolphins may favor nocturnal refuges as a reaction to human disturbance in highly regulated rivers.Managing human disturbances in conjunction with habitat heterogeneity can improve the persistence of riverine cetaceans.Here,we document behavioral and ecological information pertaining to GRD,which is essential to the formation of river dolphin recovery plans that link ecological perspectives to planning and management.
文摘mt DNA 16 S r RNA基因序列分析支持将现生淡水豚 4个属归入不同的科 ,即白暨豚科(L ipotiidae)、恒河豚科 (Platanistidae)、亚河豚科 (Iniidae)和弗西豚科 (Pontoporidae) .基于邻接法的系统发生分析显示淡水豚类由白暨豚 +恒河豚和弗西豚 +亚河豚两个单系组成 ,但两个单系之间并无姊妹关系 .淡水豚类是并系的 .16 S r RNA基因的系统发生树与 mt DNA细胞色素 b基因和12 S r RNA基因的系统发生树并不完全一致 .这种差异一方面可能反映了不同的基因树间的差异 ,但也可能与本文分析的 16 S r RNA基因片段中变异位点数和简约信息位点数较少有关 .因此 ,有必要增加序列长度来进一步验证 .
