Widespread species that inhabit diverse environments possess large population sizes and exhibit a high capacity for environmental adaptation,thus enabling range expansion.In contrast,narrow-range species are confined ...Widespread species that inhabit diverse environments possess large population sizes and exhibit a high capacity for environmental adaptation,thus enabling range expansion.In contrast,narrow-range species are confined to restricted geographical areas and are ecologically adapted to narrow environmental conditions,thus limiting their ability to expand into novel environments.However,the genomic mechanisms underlying the differentiation between closely related species with varying distribution ranges remain poorly understood.The Niviventer niviventer species complex(NNSC),consisting of highly abundant wild rats in Southeast Asia and China,offers an excellent opportunity to investigate these questions due to the presence of both widespread and narrow-range species that are phylogenetically closely related.In the present study,we combined ecological niche modeling with phylogenetic analysis,which suggested that sister species cannot be both widespread and dominant within the same geographical region.Moreover,by assessing heterozygosity,linkage disequilibrium decay,and Tajima's D analysis,we found that widespread species exhibited higher genetic diversity than narrow-range species.In addition,by exploring the“genomic islands of speciation”,we identified 13 genes in highly divergent regions that were shared by the two widespread species,distinguishing them from their narrow-range counterparts.Functional annotation analysis indicated that these genes are involved in nervous system development and regulation.The adaptive evolution of these genes likely played an important role in the speciation of these widespread species.展开更多
Ehrlichia(Anaplasmataceae family)are obligatory intracellular bacteria that infect humans and animals.They are hosted by mammals such as canines,bovines and wild rodents,and are vectored by ticks.In this study,we coll...Ehrlichia(Anaplasmataceae family)are obligatory intracellular bacteria that infect humans and animals.They are hosted by mammals such as canines,bovines and wild rodents,and are vectored by ticks.In this study,we collected 121 rodent samples comprising 67 Niviventer fulvescens,27 Rattus tanezumi,24 Chiromyscus sp.,2 Rattus nitidus and 1 Leopoldamys edwardsi from Hainan province,which includes the second largest island in China.The presence and genetic diversity of Ehrlichia species was evaluated and characterized by amplification and sequencing of 16S rRNA,groEL and gltA genes.An Ehrlichia species was detected in 5 of the 67 Niviventer fulvescens samples(7.46%).The 16S rRNA,groEL and gltA genes showed the highest identity to known Ehrlichia sequences(99.20%,89.87%and 83.86%,respectively).In the phylogenetic trees they formed a cluster distinct from all other species.We propose that this species is a putative novel Ehrlichia species,which we suggest be named Candidatus Ehrlichia hainanensis.Its pathogenicity to humans remains to be further researched,and molecular surveillance in local populations is needed.展开更多
Asymmetric competition occurs when some species have distinct advantages over their competitors and is common in animals with overlapping habitats and diet.However,the mechanism allowing coexistence between asymmetric...Asymmetric competition occurs when some species have distinct advantages over their competitors and is common in animals with overlapping habitats and diet.However,the mechanism allowing coexistence between asymmetric competitors is not fully clear.Chinese white-bellied rats(Niviventer confucianus,CWR)and Korean field mice(Apodemus peninsulae,KFM)are common asymmetric competitors in shrublands and forests west of Beijing city.They share similar diet(e.g.plant seeds)and activity(nocturnal),but differ in body size(CWR are bigger than KFM),food hoarding habit(CWR:mainly larder hoarding;KFM:both larder and scatter hoarding),and ability to protect cached food(CWR are more aggressive than KFM).Here,we tested seed competition in 15 CWR-KFM pairs over a 10-day period under semi-natural enclosure conditions to uncover the differences in food hoarding,cache pilferage,and food protection between the 2 rodents,and discuss the implication for coexistence.Prior to pilferage,CWR harvested and ate more seeds than KFM.CWR tended to larder hoard seeds,whereas KFM preferred to scatter hoard seeds.Following pilferage,CWR increased consumption,decreased intensity of hoarding,and pilfered more caches from KFM than they lost,while KFM increased consumption more than they hoarded,and they preferred to hoard seeds in low and medium competition areas.Accordingly,both of the 2 rodent species increased their total energy consumption and hoarding following pilferage.Both rodent species tended to harvest seeds from the source,rather than pilfer caches from each other to compensate for cache loss via pilferage.Compared to CWR,KFM consumed fewer seeds when considering seed number,but hoarded more seeds when considering the seeds’relative energy(energy of hoarded seeds/rodent body mass2/3)at the end of the trials.These results suggest that asymmetric competition for food exists between CWR and KFM,but differentiation in hoarding behavior could help the subordinate species(i.e.KFM)hoard more energy than the dominant species(i.e.CWR),and may contribute to their coexistence in the field.展开更多
基金supported by the Guangdong Provincial Key R&D Program (2022B1111040001)the Second Tibetan Plateau Scientific Expedition and Research Program (2019QZKK0402/2019QZKK0501)National Natural Science Foundation of China (32170426)。
文摘Widespread species that inhabit diverse environments possess large population sizes and exhibit a high capacity for environmental adaptation,thus enabling range expansion.In contrast,narrow-range species are confined to restricted geographical areas and are ecologically adapted to narrow environmental conditions,thus limiting their ability to expand into novel environments.However,the genomic mechanisms underlying the differentiation between closely related species with varying distribution ranges remain poorly understood.The Niviventer niviventer species complex(NNSC),consisting of highly abundant wild rats in Southeast Asia and China,offers an excellent opportunity to investigate these questions due to the presence of both widespread and narrow-range species that are phylogenetically closely related.In the present study,we combined ecological niche modeling with phylogenetic analysis,which suggested that sister species cannot be both widespread and dominant within the same geographical region.Moreover,by assessing heterozygosity,linkage disequilibrium decay,and Tajima's D analysis,we found that widespread species exhibited higher genetic diversity than narrow-range species.In addition,by exploring the“genomic islands of speciation”,we identified 13 genes in highly divergent regions that were shared by the two widespread species,distinguishing them from their narrow-range counterparts.Functional annotation analysis indicated that these genes are involved in nervous system development and regulation.The adaptive evolution of these genes likely played an important role in the speciation of these widespread species.
基金funded by the National Important Scientific&Technology Project [2018ZX10101002-002 and2018ZX10732401-001]the Inner Mongolia Natural Science[grant No. 2016MS0859]+1 种基金the Key Scientific and Technology Project of Inner Mongolia Autonomous Region [grant No. 2021ZD0006]the National Natural Science Foundation of China [grant No. 82102390]。
文摘Ehrlichia(Anaplasmataceae family)are obligatory intracellular bacteria that infect humans and animals.They are hosted by mammals such as canines,bovines and wild rodents,and are vectored by ticks.In this study,we collected 121 rodent samples comprising 67 Niviventer fulvescens,27 Rattus tanezumi,24 Chiromyscus sp.,2 Rattus nitidus and 1 Leopoldamys edwardsi from Hainan province,which includes the second largest island in China.The presence and genetic diversity of Ehrlichia species was evaluated and characterized by amplification and sequencing of 16S rRNA,groEL and gltA genes.An Ehrlichia species was detected in 5 of the 67 Niviventer fulvescens samples(7.46%).The 16S rRNA,groEL and gltA genes showed the highest identity to known Ehrlichia sequences(99.20%,89.87%and 83.86%,respectively).In the phylogenetic trees they formed a cluster distinct from all other species.We propose that this species is a putative novel Ehrlichia species,which we suggest be named Candidatus Ehrlichia hainanensis.Its pathogenicity to humans remains to be further researched,and molecular surveillance in local populations is needed.
文摘Asymmetric competition occurs when some species have distinct advantages over their competitors and is common in animals with overlapping habitats and diet.However,the mechanism allowing coexistence between asymmetric competitors is not fully clear.Chinese white-bellied rats(Niviventer confucianus,CWR)and Korean field mice(Apodemus peninsulae,KFM)are common asymmetric competitors in shrublands and forests west of Beijing city.They share similar diet(e.g.plant seeds)and activity(nocturnal),but differ in body size(CWR are bigger than KFM),food hoarding habit(CWR:mainly larder hoarding;KFM:both larder and scatter hoarding),and ability to protect cached food(CWR are more aggressive than KFM).Here,we tested seed competition in 15 CWR-KFM pairs over a 10-day period under semi-natural enclosure conditions to uncover the differences in food hoarding,cache pilferage,and food protection between the 2 rodents,and discuss the implication for coexistence.Prior to pilferage,CWR harvested and ate more seeds than KFM.CWR tended to larder hoard seeds,whereas KFM preferred to scatter hoard seeds.Following pilferage,CWR increased consumption,decreased intensity of hoarding,and pilfered more caches from KFM than they lost,while KFM increased consumption more than they hoarded,and they preferred to hoard seeds in low and medium competition areas.Accordingly,both of the 2 rodent species increased their total energy consumption and hoarding following pilferage.Both rodent species tended to harvest seeds from the source,rather than pilfer caches from each other to compensate for cache loss via pilferage.Compared to CWR,KFM consumed fewer seeds when considering seed number,but hoarded more seeds when considering the seeds’relative energy(energy of hoarded seeds/rodent body mass2/3)at the end of the trials.These results suggest that asymmetric competition for food exists between CWR and KFM,but differentiation in hoarding behavior could help the subordinate species(i.e.KFM)hoard more energy than the dominant species(i.e.CWR),and may contribute to their coexistence in the field.
