Diet,food availability,and climatic factors drive ranging behavior in white-headed langurs in the limestone forests of Guangxi,southwest China

Changes in abiotic and biotic factors can affect the efficiency of biological systems in animals,forcing them to adjust their behaviors in response to daily and seasonal variations.From September 2016 to August 2017,we collected ranging behavior data on four groups of white-headed langurs(Trachypithecus leucocephalus)in the Guangxi Chongzuo White-Headed Langur National Nature Reserve,Guangxi,southwest China.We simultaneously analyzed how multiple ecological factors affect langur ranging behavior,which should facilitate our understanding of the potential mechanisms underlying their adaptation to limestone habitats.Results showed that langur ranging behavior was significantly affected by diet composition,food availability,and climatic factors.Specifically,moving time and daily path length increased with the increase in dietary diversity.Furthermore,moving time and daily path length were positively associated with the availability of fruit and relative humidity of the forest,and moderately associated with temperature and relative humidity of bare rock.Our study demonstrated that langurs maintain stable moving and feeding times and exhibit a short daily travel distance,likely adopting an energy-conserving behavioral strategy in response to food shortages and high temperatures in the fragmented karst forest.These results highlight the importance of food availability and temperature in shaping the ranging behavior of these karst-dwelling primates.

Ultrafast optical spectroscopy of surface-modified silicon quantum dots: unraveling the underlying mechanism of the ultrabright and color-tunable photoluminescence

In this work,the fundamental mechanism of ultrabright fluorescence from surface-modified colloidal silicon quantum dots is investigated in depth using ultrafast spectroscopy.The underlying energy band structure corresponding to such highly efficient direct bandgap-like emissions in our surface-modified silicon quantum dots is unraveled by analyzing the transient optical spectrum,which demonstrates the significant effect of surface molecular engineering.It is observed that special surface modification,which creates novel surface states,is responsible for the different emission wavelengths and the significant improvement in the photoluminescence quantum yields.Following this essential understanding,surface-modified silicon quantum dots with deep blue to orange emission are successfully prepared without changing their sizes.