变色树蜥应对全球气候变暖的能量分配策略

Global warming has been thought to be a key threat to biodiversity. Based on the findings of previous studies, we will investigate the responses of oriental garden lizards (Calotes versicolor) to global warming, especially the strategy of energy allocation during the winter, by analyzing gut microbiota, transcriptome, ecological immunology and life-history traits of individuals both in the field and in the laboratory. We hypothesize: (1) compared to individuals under the normal winter, individuals in warm winters will increase maintenance costs of energy and reduce energy allocation to reproduction, (2) individuals need to obtain energy from the environment after hibernation, thus altering the timing of egg-laying, (3) females that lay eggs later in the season will tend to produce larger but fewer eggs to enhance offspring fitness, (4) climate warming will change the diversity of gut microbiota, immune capacity and energy metabolism in C. versicolor. Our study is the first to explain the ecological and physiological responses to climate warming in lizards, and we hope to find something conceptually new that has never been reported for any other taxa.

全球气候变暖是导致全球生物多样性下降的重要因素。在以往的研究基础上，本项目以分布在中国南北两个种群的变色树蜥为研究对象，结合野外研究和室内操纵实验，整合肠道微生物多样性分析、转录组学、生态免疫学和生活史特征，研究变色树蜥应对气候变暖，尤其是过冬阶段的能量分配策略。以检验以下假设：(1)与正常过冬的变色树蜥相比，遭遇暖冬的变色树蜥在冬眠期间会增加维持能耗，进而导致储存用于繁殖的能量下降，(2)冬眠后需要从外界获取能量，将影响产卵时间，(3)若产卵期后延，变色树蜥将倾向产较大而较少的卵，以增加后代适合度，(4)气候变暖将导致肠道菌群多样性下降，免疫能力也会出现相应改变，同时也将对个体能量代谢出现调控。本项目首次阐明蜥蜴应对全球气候变暖的生理生态反应，并望获得区别于其他类群的新的发现。

为了探讨热带蜥蜴如何应对全球气候变暖的能量响应，选择了气候变换相对稳定(三亚种群)和变化差异较大(五指山种群)的的两个种群，以研究其能量响应、肠道菌群以及生活史变化。在繁殖实验中发现SVL为77.32mm的雌性母体也能产下卵，改变以往认为SVL ≥ 78.9mm的标准来判断个体性成熟的观点。三亚夏-雨季标准代谢率高于五指山夏-雨季标准代谢率，三亚冬-旱季标准代谢率高于五指山冬-旱季标准代谢率，五指山夏-雨季标准代谢率高于五指山冬-旱季标准代谢率，三亚夏-雨季标准代谢率高于三亚冬-旱季标准代谢率。Bacteroidetes，Firmicutes和Proteobacteria门是变色树蜥肠道菌群的优势菌群，并且Bacteroidetes和Firmicutes门呈现出随着肠段的延伸，相对丰富度增加的趋势，而且Bacteroides属，Coprobacillus属，Eubacterium属，Parabacteroides属和Ruminococcus属，以及Odoribacteraceae科和Rikenellaceae科在变色树蜥肠道后段是优势类群。由于变色树蜥雌雄之间头部大小存在两性异型，造成食物存在差异，导致变色树蜥肠道菌群存在性别差异，Bacteroide 属菌群在雌性占主要地位，而Ochrobactrum属菌群却在雄性个体中占主要地位。由于人工饲养的饲料比较单一，导致在饲养个体中，Firmicutes和Proteobacteria门菌群下降，但Bacteroidetes和Verrucomicrobia门菌群却呈现上升趋势，Clostridium 属菌群是优势菌群。应对雨季和旱季的气候变化，五指山种群和三亚种群的过冬适应策略，表达差异基因主要涉及的生物过程是各类代谢过程以及生物合成，但是涉及的代谢途径存在差异。本项目将为热带变温动物应对全球气候变暖从能量角度提供科学依据。