Species recognition and the divergences in the chemical and ultrasonic signals between two coexisting Rattus species

The ability to recognize and differentiate between conspecifics and heterospecifics as well as their signals is critical for the coexistence of closely related species.In the genus Rattus,species are morphologically similar and multiple species often coexist.Here,we investigated the interspecific recognition and signal differentiation of two sympatric rat species,the brown rat(Rattus norvegicus,RN)and the Asian house rat(Rattus tanezumi,RT).In a two-way choice test,both RN and RT females showed a preference for conspecific male rats to heterospecific ones.RT females showed a significant preference for accessible urine of males of same species to those of other species,but not for the inaccessi-ble urine.On the other hand,there were significant differences in the structural characteristics of the ultrasonic vocalization emitted by males of these two rat species.Sodium dodecyl sulphate-polyacrylamide gel electrophoresis(SDS-PAGE)and isoelectric focusing electrophoresis unveiled that major urinary proteins(MUPs)in voided urine were more highly expressed in RN males versus RT males.The interspecific dif-ferences of urinary volatile compounds were also discussed.In conclusion,female rats had the ability to distinguish between males of either species.

C:N:P stoichiometry of Ericaceae species in shrubland biomes across Southern China:influences of climate,soil and species identity

Aims Carbon(C),nitrogen(N)and phosphorus(P)stoichiometry strongly affect functions and nutrient cycling within ecosystems.However,the related researches in shrubs were very limited.In this study,we aimed to inves-tigate leaf stoichiometry and its driving factors in shrubs,and whether stoichiometry significantly differs among closely related species.Methods We analyzed leaf C,N and P concentrations and their ratios in 32 species of Ericaceae from 161 sites across southern China.We examined the relationships of leaf stoichiometry with environmen-tal variables using linear regressions,and quantified the interactive and independent effects of climate,soil and species on foliar stoi-chiometry using general linear models(GLM).Important Findings The foliar C,N and P contents of Ericaceae were 484.66,14.44 and 1.06 mg g−1,respectively.Leaf C,N and P concentrations and their ratios in Ericaceae were significantly related with latitude and altitude,except the N:P insignificantly correlated with latitude.Climate(mean annual temperature and precipitation)and soil properties(soil C,N and P and bulk density)were significantly influenced element stoichiom-etry.The GLM analysis showed that soil exerted a greater direct effect on leaf stoichiometry than climate did,and climate affected leaf traits mainly via indirect ways.Further,soil properties had stronger influ-ences on leaf P than on leaf C and N.Among all independent factors examined,we found species accounted for the largest proportion of the variation in foliar stoichiometry.These results suggest that species can largely influence foliar stoichiometry,even at a lower taxonomic level.