Studies On Morphological Geographic Variation And Locomotor Performance Of Eremias Arguta

Exploring the links between morphological variation across species,populations or individuals within the same population with their habitat use and functional performance is a central issue in ecology,using the ’Morphology-Performance-Fitness’ component to test the adaptive link between ecology and morphology.In this study,the morphology,functional performance and ecological adaptations among different populations of Eremias arguta were analysed in terms of morphological indicators,food composition,bite force and locomotor performance on different substrates,the showing that:(1)Digit ratios are the ratios between different toe lengths of animal.Digit ratios are often regarded as one of the markers of early androgen/estrogen exposure,which affect the morphological characteristics,behavioral performance and physiological mechanism of lizards,and are related to lizards fitness.In this study,by measuring the digit length and calculating the digit ratios,the sexual dimorphism of digit length and digit ratios was investigated in three geographic populations of the steppe-runners(Eremias arguta)from Xinjiang Uyghur Autonomous Region.The results showed that the males were significantly larger than the females in the second digit lengths of the hind limbs in Yili population.The males were significantly larger than the females in the second,third,fourth and fifth digit lengths of the fore and hind limbs in Fuyun population;the females were significantly larger than males in the hind second-to-fourth digit length ratio.In the Tacheng population,the adult males were significantly longer than the females in the first and fifth digit lengths of the forelimb and the first,second,third and ‘fourth digit lengths of the hind limb;and the adult males were significantly larger than females in the hind second-to-third digit length ratios.There is no uniform pattern of sexual dimorphism in the digit length and digit ratios among the three geographic populations of the E.arguta,and may have evolved independently.There are significant differences in the sexual dimorphism of digit length and digit ratios among different geographic populations,and the mechanisms need to be further studied.(2)The phenomenon of sexual dimorphism exists in the femoral pore indices of three populations of E.arguta,the males were significantly larger than the females in the gland number and total number of femoral pore to knee bend scales in Yili and Fuyun populations,the males were significantly larger than the females in the pore diameter and pore surface area in Yili,Fuyun and Tacheng populations.Significant differences were found between females and males of three populations,showed consistent with a trade-off between sexual and natural selection for each femoral pore indices in the widespread species of E.arguta The femoral pore area between two sexes of the three populations of E.arguta increased with increasing mean annual temperature and annual precipitation.which are consistent with the prediction of the "within-channel compensation hypothesis".(3)The maximum sprint speed and endurance of three populations of E.arguta on different substrates did not different significantly between two sexes,which conform to the "jack of all trades and master of none" strategy.However,when the three populations were combined,it was found that the maximum sprint speed of males on mud substrates was significantly greater than that on gravel and sand substrates,suggesting that the males showed the “home field advantage” strategy in terms of maximum sprint speed,while the females showed the "jack of all trades and master of none" strategy in terms of maximum sprint and endurance for both females and males showed the "jack of all trades and master of none" strategy.In conclusion,it is suggested that the locomotor performance of E.arguta on different substrates is in the middle of the transition between the "jack of all trades and master of none" and the "home field advantage" strategies.(4)Sexual dimorphism exists in bite force among three populations of E.arguta and all males were significantly larger than the females.Head depth and snout-vent length were the main factors influencing bite force in males,while head width and head volume were the main factors influencing bite force in females.The bite force of E.arguta is the result of a trade-off between sexual selection and natural selection.The food by two sexes in all three populations of E.arguta was dominated by Coleoptera and Orthoptera,and there were no significantly in the medium and hard food between two sexes,and the ecological niche overlap was high,probably as a result of the trade-off the natural selection.But there were significantly in the frequency and size of food between two sexes,which is consistent with the prediction of the “sex-specific niche divergence hypothesis”.The sexual dimorphism and functional performance of different populations of E.arguta is the result of a combination of the sexual selection hypothesis,sex-specific niche divergence hypothesis and natural selection pressures.