| Reptiles are widely distributed and highly dependent on the environment,so there are great intraspecific and interspecific variations in life history traits due to environmental differences in each geographical range.Altitude,as a complex environmental factor,can have a great impact on the life history variation of reptiles.As the "roof of the world",the Qinghai-Tibet Plateau has a good advantage in the life history variation of animals along the altitude.Our research site was located in Dangjin Mountains,Aksai County,Gansu province.Up the mountain,we choose three populations of Phrynocephalus vlangalii as the research objects:low(2600 m),middle(3400 m),high(3600 m).In order to explore the variation pattern of their life history characteristics in different altitudes and explore the reasons of their variations,we observed and reared them in some feeding terrarium in the field.The results showed that:(1)The measurement of the surface temperature at three altitudes showed that the average surface temperature at middle altitude was the lowest,followed by high altitude and the highest at low altitude.The average surface temperature at low altitude was 8.89? higher than that at high altitude,and 10.09? higher than that at middle site,and there were significant differences.The average surface temperature at high altitude was 1.2? higher than that of the middle altitude,and there was no significant difference.This indicates that the surface temperature in Dangjin Mountains decreases with the increase of altitude.However,the average surface temperature in lower altitude may be lower due to environmental factors differences in wind speed,humidity and topography in areas where there was not much elevation difference.There was no significant difference in relative food availability between altitudes,which indicated that the distribution of food resources in the environment was equal between populations.(2)There were significant differences in the body size of the female P.vlangalii at high,middle and low populations,and the female P.vlangalii at middle population had snout-vent length and body mass,while the female P.vlangalii at low population had the smallest body size.This may be caused by the difference of surface temperature at different altitudes,which leads to the difference in the distribution of energy trade-offs among different populations.The offsprings body size at middle population was the largest,followed by that at high population and the smallest at low population,which was caused by the trade-offs and distribution of reproductive energy by the mother in order to make the offsprings had higher survival rate over winter in cold environment.(3)The high,middle and low three populations of female P.vlangalii production time in advance along with the rise of temperature,and high population P.vlangalii matrix production longer duration was due to the changeable environment leads to a matrix exist differences in microenvironment heat resource utilization,the high population each parent differently on the regulation of embryonic development,so as to prolong the duration of production.The larger and small number of offsprings produced by the middle P.vlangalii were related to the trade-offs of reproductive strategies by the female P.vlangalii.(4)The growth rate of offsprings of P.vlangalii at low population was the fastest,which was related to the food resources and environmental temperature in the environment.The environmental temperature affects the metabolic rate of offsprings.The average surface temperature at low altitude is higher,which accelerated growth rate of offsprings.The differences of body mass growth rate and snout-vent length growth at high and middle population were related to the trade-offs allocation of thermal resources,and there was no significant difference in locomative performance among the offsprings at three populations. |
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