沙蜥属蜥蜴形态和生活史表型种间和种内变异的代谢相关性

Metabolism is one of the most fundamental biological processes, encompassing all of the reactions catalyzed by enzymes to generate and use energy; metabolic rate is the most fundamental biological rate because it is the rate of energy uptake, transformation and allocation and, as such, is integrally related to the pace of life. Resources (energy) acquired by animals through feeding should be allocated between two main competing demands, maintenance and production. Maintenance costs include the energy costs for basal or standard metabolism and other activities essential for the continuity of an individual’s life, and energy allocated to production hierarchically supports somatic tissue growth, reproduction and fat storage. This hierarchical allocation of energy, when coupled with the fact that low energy costs for maintenance can translate into an increased potential to allocate more energy in growth and reproduction, suggests three hypotheses that will be tested in this study: (1) populations or species with higher maintenance costs should be less likely to invest more energy in growth and thus should be smaller in body size, shorter in limbs and body appendages, greater in body surface and less able to support the body; (2) populations or species with higher maintenance costs should be less likely to invest more energy in reproduction and thus should be lower in reproductive output and reproductive frequency; and (3) populations or species where selection favors fast metabolism in cold environments as predicted by metabolic cold adaptation hypothesis should evolve smaller body size (thus exhibiting an anti-Bergmann’s rule) and shorter limbs and body appendages (thus exhibiting an Allen’s rule). Here, we will use 12 (6 oviparous and 6 viviparous) species of Phrynocephalus lizards found in China to test these hypotheses. Specifically, We will collect adult lizards from various localities covering their entire ranges in China to gather morphological (snout-vent length, body mass, tail length, snout length, abdomen length and fore- and hind-limb length) and life-history (clutch or litter size, clutch or litter mass, egg or neonate mass and size at maturity) data, and to determine standard metabolic rates for lizards at body temperatures ranging from 20 ℃ to 38 ℃. We will use 2 nDNA (RAG1 and PDC) and 2 mtDNA (Cyt b and COI) marks to resolve relationships among intra- and inter-specific units, and then use phylogenetic ANOVA or ANCOVA and phylogenetic generalized least squares (PGLS) implemented in R to determine metabolic correlates of inter- and intra-specific variation in morphological and life-history phenotypes in Phrynocephalus lizards. The project, if funded, will allow us to find something conceptually new that has never been reported for any other animal taxa.

代谢是最基本的生物过程之一，代谢率是最基本的生物过程速率。动物摄入的能量须在维持和生产两个彼此冲突的能量需求之间进行分配，能量分配的优先权按递减顺序排列依次是：维持、生长、繁殖和储能。申请人拟在沙蜥属国内分布区全境采集12种成年蜥蜴，收集形态、生活史和20-38℃体温下的标准代谢率数据，用2个核基因和2个线粒体基因标记重建谱系关系，综合利用谱系ANOVA或ANCOVA和PGLS回归分析，阐述形态和生活史表型种内和种间变异的代谢相关性，拟检验3个假设：1、维持能耗较高的种群或物种应具有体形较小、相对体表面积较大或负重能耗较高的特征；2、维持能耗较高的种群或物种应具有繁殖输出较小、繁殖频率较低或繁殖总能耗较低的特征；3、代谢冷适应假设若适用于该属，则沙蜥个体大小变异的空间格局应与贝格曼法则相反、身体突出部分变异的空间格局应与阿伦法则相同。本项目若能实施，可获得区别于其它生物类群的创新发现。

代谢是最基本的生物过程之一，涉及由酶催化产生并利用能量的所有反应；代谢率是最基本的生物过程速率，反映能量摄取、转化和分配的综合速率，决定生命节律。动物摄入的能量须在维持和生产两个彼此冲突的能量需求之间进行分配，能量分配的优先权按递减顺序排列依次是：维持、生长、繁殖和储存。本项目在8省区、88个覆盖沙蜥属国内分布区全境的采样点采集了14种（含2个疑似乌拉尔沙蜥同物异名种和1个疑似荒漠沙蜥同物异名种）成年蜥蜴，收集形态、生活史和20-38 ℃体温下的标准代谢率数据；用2个核基因和2个线粒体基因标记重建谱系关系，整合利用谱系ANOVA或ANCOVA和PGLS回归分析，阐述形态和生活史表型种内和种间变异的代谢相关性；设计不同物种和温度组合的析因实验，用16S rRNA基因测序技术分析肠道菌群，比较种间差异以检验肠道菌群是否利用蜥蜴适应冷气候环境。本项目获得以下5方面主要结果：1）沙蜥属蜥蜴形态和生活史特征的种间差异和种内地理变异显著，局域环境和地理隔离驱动遗传和表型分化；2）邻域物种分化是沙蜥属内物种分化的重要机制，不同生态型的繁殖生活史和形态表型呈现相应的分化；3）沙蜥属蜥蜴标准代谢率地理变异显著，个体大小和繁殖特征具有显著的代谢相关性；4）沙蜥属蜥蜴标准代谢率季节变异显著，与能量分配优先顺序的季节变化有关；5）肠道菌群对冷气候区蜥蜴适应低温环境具有重要作用。从以上主要结果可以得出以下结论：1）维持与生长能量权衡假设适用于解释沙蜥个体大小和体型的种内和种间差异，即维持能耗较高的种群或物种具有体形较小、相对体表面积较大或负重能耗较高的特征；2）维持与繁殖能量权衡假设适用于解释沙蜥繁殖输出的种内和种间差异，即维持能耗较高的种群或物种应具有繁殖输出较小、繁殖频率较低或繁殖总能耗较低的特征；3）代谢冷适应假设适用于解释个体大小和繁殖输出的种内和种间差异，即个体大小变异的空间格局符合反贝格曼法则预测、身体突出部分变异的空间格局符合阿伦法则预测。

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