| The Orental tree squirrels of Callosciurinae are widely distributed in South China because of their good adaptability and large population size.They are important species that maintain the balance of forest ecosystems.In the Karst Plateau of Guizhou,there are many species of Orental tree squirrels coexist,but no relevant research has been conducted.In order to clarify the distribution characteristics of Orental tree squirrels in Guizhou,and explore the unique karst topography and geomorphology of Guizhou and Guizhou's transitional fauna characteristics in central and southwestern China,the Orental tree squirrels differentiated in geographical populations in different regions of Guizhou to promote this Basic biology research and resource conservation management of species.In this study,sampling was performed based on the characteristics of mammalian zoning in Guizhou.A total of 87 adult samples were collected from five main distribution areas in Guizhou.At the same time,a sample line method and an infrared camera survey method were used in conjunction with the scientific investigation results of 12 nature reserves in Guizhou.The population resources,population distribution,and habitat use of different species of Orental tree squirrels in Guizhou were analyzed,and the morphological and genetic differentiation among different species and geographical populations were explored using geometric morphometry and molecular sequencing techniques.The results show:(1)Combining literature and field investigation records,Guizhou Callosciurinae subfamily includes mainly Callosciurus(C.erythraeus)?Dremomys(D.pyrrhomerus)and(D.pernyi)?and Tamiops(T.swinhoei),There are four species of Guizhou.The species abundance measured by the capture rate showed that the capture rate of C.erythraeus was 0.64%,that of T.swinhoei was 0.15 %,that of D.pyrrhomerus was 0.089 %,that of D.pernyi was 0.11 %;Infrared camera shooting rate,the highest for C.erythraeus the 0.68%,D.pyrrhomerus is 0.3%,D.pernyi 0.32%,and the shooting rate of was T.swinhoei only 0.03%.In addition,the distribution density of C.erythraeus is 10 animals/hm2 in the distribution density of species,and the distribution density of is only D.pyrrhomerus 1.2 animals/hm2.It is obvious that the population of C.erythraeus in Guizhou is the dominant species,and the population of D.pyrrhomerus is relatively the smallest.(2)Distribution of different geographical regions,the resources of Guizhou Callosciurinae rats show more distribution in the east and southeast and less in the west and northwest,Among the four species of Callosciurinae,the C.erythraeus has the widest distribution and is distributed in all zoning units.T.swinhoei is the second and is distributed in about 60% of the divergence units.The narrow distribution of the D.pernyi and the D.pyrrhomerus is relatively narrow.In general,Callosciurinae rats in Guizhou are concentrated in the Northeast Guizhou lower-mountain hill prefecture and the South Guizhou lower-mountain river-valley province,with the least in West Guizhou plateau midium-mountain province and The plateau prefecture of Northwestern part of West Guizhou.(3)With different altitude gradients,the 900-1500 m four species of squirrels are distributed.Between 700-900 m,the distributions of C.erythraeus,T.swinhoei,D.pyrrhomerus are mainly distributed.The squirrels of D.pernyi begin to appear between 900-1100m;the 1500-700 m are mainly distributed in the C.erythraeus and T.swinhoei.Low woodland belts over1700 m,there are few Callosciurinae distributed.In addition,it is not difficult to see that as the altitude of the vertical zone continues to increase,the population density of different species also shows a downward trend.(4)With regard to the use of habitats,the Chi-square test showed that there were significant differences among the three squirrels in slope,habitat use,and human disturbance(?2 = 11.167,df = 2,P = 0.04 <0.05):C.erythraeus are more efficient in mountainous areas with slopes of 20° to 40°,D.pyrrhomerus and D.pernyi use more than 20° of gentle slopes.By statistics of frequency(based on the percentage of the total number of appearances of each species in this sample),it was found that the utilization rate of <20° for gentle slopes is greatest for D.pyrrhomerus,and gentle slopes for D.pernyi.D.pernyi had the highest utilization of shrubs(50%),C.erythraeus had a higher utilization rate of coniferous forests(46.7%),and D.pyrrhomerus had higher utilization of evergreen broad-leaved forests(38.5%).D.pyrrhomerus squirrels use higher(46.2%)for human disturbance distances <50 m,and C.erythraeus use >300 m(40%)for human intervention distances.According to the principal component analysis,the main factors habitat use of C.erythraeus are canopy density,food abundance,terrain,and human interference;the main factors affecting habitat use of D.pyrrhomerus are terrain,food richness,canopy closure,and water source distance.The main ecological factors influencing habitat use of D.pernyi are terrain and water resources.(5)Using the mandibular geometry analysis,it was found that there was a significant difference in mandibular morphology between the C.erythraeus,the D.pernyi,the D.pyrrhomerus,and the T.swinhoei(F=193.15,P=0.0036).Mandibular deformation mainly occurred in the morphological variables such as the anterior edge of molar tooth row,the ventral-most point on ventral border of angular process,the dorsal-most point on ventral border of horizontal ramus,the anterior limit of masseteric ridge,and the mental foramen.These morphological differences are related to feeding ability and feeding habits among species,reflecting the ecological adaptability of different species.(6)Morphological analysis of the two species of the genus Spermophilus,the D.pyrrhomerus and the D.pernyi.The difference in mandibular morphology between two similar species originated from four morphological variables such as maximum of curvature between molar alveolar and horizontal ramus and the antero-ventral border of incisive alveolus,the anterior limit of masseteric ridge,the mental foramen.The reasons for these differences are related to the differences in ecological habits and feeding habits of two similar species.(7)Geometric morphometrics results show that the differentiation of five geographical populations of C.erythraeus is not obvious,It can be seen from the locally distorted grid pattern that the five geographical populations of C.erythraeus are distorted in the two mandible morphological variables such as the anterior limit of masseteric ridge and the mental foramen,but this distortion does not change much.The main component scatter plot shows that 5 C.erythraeus in different regions are clustered together and the differentiation is not obvious.The sequencing of the Cytb gene and the establishment of the BI development tree showed that the C.erythraeus of different geographic populations in Guizhou were clustered together and did not show significant differentiation.Therefore,although the coat color of C.erythraeus in different regions of Guizhou is slightly different,the geographic populations did not significantly differentiate.This study for the first time explored the distribution of resources of the species Callosciurinae in Guizhou Province,and basically found out the quantity and distribution status of Callosciurinae species in Guizhou province.At the same time,the mandibular morphological differentiation of the subfamily species population of Callosciurinae was explored,which laid the foundation for the further study of Callosciurinae species. |
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