【作者】 王立宏；

【导师】 Martin Plath；

【作者基本信息】 西北农林科技大学 ， 水生生物学， 2021， 博士

【摘要】 ?（Hemiculter leucisculus）和贝氏?（Hemiculter bleekeri）是我国比较常见的小型土著鱼类,它们均隶属于鲤科（Cyprinidae）、鲌亚科（Culterinae）中的?属（Hemiculter）。?和贝氏?具有突出的生境适应性和较高的入侵潜力,是我国许多水体中的优势种,它们如何适应高度异质性的环境并成为优势种,是值得关注的。本研究通过几何形态学的方法获得了18个地理种群?的形态差异,对?形态与气候的关系进行了探索;以线粒体基因Cytb,核基因RAG2与Rho做为分子标志,分析了来自不同水系的这18个?种群的遗传结构和遗传多样性,对?的亲缘地理学进行了研究,并就形态差异与遗传分化的关系作了初步的探讨;此外,还对来自8个地理种群的?脑及脑组成部分体积的差异与气候的关系进行了研究;同时我们也利用几何形态学的方法,分析了长江流域6个不同地点的贝氏?的形态差异与气候的关系;以Cytb、RAG2、Rho做为分子标志分析了贝氏?的遗传结构和遗传多样性,进行了亲缘地理学的研究,分析了贝氏?的形态差异与遗传距离的关系。获得以下研究结果:1、?的大小和形态与气候相关,沿气候的纬度、经度梯度存在着显著的变异。沿纬度梯度,高纬度的北方地区鱼体大;沿经度梯度,内陆地区、高海拔地区比沿海、低海拔地区的鱼体大;但是在气候交互效应的作用下变化比较复杂,存在着一个临界点,临界点两侧的变化趋势相反。鱼体的形态沿经度梯度,内陆地区的?较沿海地区的体高小,臀鳍前移并变长,背鳍后移、背部曲线加深突出,尾柄变短体积减小,气候的交互项效应沿经度梯度在南方和北方的作用大小不同,甚至对某些性状的效应还相反;沿纬度梯度,高纬度北方的?较南方的体高变小、臀鳍变短,尾柄变长、体积增大,交互项效应沿纬度梯度的作用在沿海地区要强于内陆。2、不同地理种群的?的脑及脑组成部分体积的差异与气候条件显著相关。沿纬度梯度,由北方到南方,端脑、下丘脑、全脑、小脑和视顶盖体积均减小;沿经度梯度,由沿海到内陆,嗅泡、下丘脑、小脑和端脑体积均增大;同时气候交互项沿纬度、经度梯度对脑及脑的某些区域体积的作用有一个临界点,在临界点的两侧,对脑体积的效应趋势是相反的。3、以线粒体基因Cytb和两个核基因RAG2、Rho做为分子标志,对?种群的遗传多样性、遗传结构和亲缘地理学进行了研究。获得的?遗传多样性参数与其它鱼类相比处于较高的水平,种群间遗传分化系数(F_ST)变化范围大,表明?种群已经高度分化。BI系统发育树、单倍型网络图、STRUCTURE分析结果、AMOVA分析结果尽管在线粒体Cytb和两个核基因RAG2、Rho之间存在差别,但是均支持北海、海南种群与其它种群分化明显,形成了独立的进化支系,此外基于线粒体Cytb的遗传结构分析的结果也支持黄河、长江水系的?种群有水系聚集的情形,存在较明显的遗传分化。遗传与地理距离的Mantel检验结果表明种群间存在着地理隔离,该结果也与遗传结构的分析互相支持。4、对?种群间形态、遗传和气候的差别执行了Mantel和偏Mantel的相关性检验,结果表明种群形态的差别在控制了遗传因素影响的前后都与气候的差别相关,这与前面陈述的18个地理种群的?的形态沿纬度、经度气候梯度都存在着显著的变化结论一致。但是?形态差异在控制气候因素后,与遗传分化不再相关。因此就目前的采样范围和实验结果,我们无法认为?形态的变化有了遗传基础,但与气候变化有关的可塑性在形态的变化中起着重要的作用。5、通过对长江流域6个地理种群的贝氏?形态和大小的研究,发现贝氏?大小和形态的变化与气候经度梯度的变化有关。通过协方差分析明确了越往内陆,贝氏?鱼体越大,尾柄越发达,尾柄体积变大,臀鳍变短,身体轮廓更具流线型。我们通过偏最小二乘法也明确了距海距离、海拔、年降水量在贝氏?鱼体形态变化中的贡献很大。6、采用线粒体基因Cytb和两个核基因RAG2、Rho做为分子标志对贝氏?种群的遗传分化、遗传结构和亲缘地理学进行了研究。遗传多样性参数表明贝氏?种群遗传多样性较高。BI系统发育树和单倍型网络图显示无地理种群聚集、无明显分支,种群间遗传分化系数较小,表明种群间分化小,STRUCTURE分析结果表明地理种群的遗传簇构成相似,AMOVA分析结果提示遗传变异主要来源于种群内,6个种群间F_ST与地理距离的Mnatel检验表明种群间无地理隔离,提示贝氏?种群间基因交流频繁。7、对贝氏?种群间的形态变化、遗传变异和气候差别执行了Mnatel检验和偏Mnatel检验,结果表明控制遗传因素前后,贝氏?形态差别与气候的变化都具有相关性,与协方差分析、偏最小二乘法结果一致,但种群间形态的差别与遗传差异不相关。本研究对?进行了广域范围的采样,另外采集了沿长江流域分布的6个地理种群的贝氏?,分别进行了生态形态学和遗传结构的研究,并分析了形态变化和气候差异的相关性、形态变化与遗传分化的相关性,探讨了可塑性机制在气候梯度相关的形态改变中起到的重要作用。更多还原

【Abstract】 Hemiculter leucisculus and Hemiculter bleekeri are small,widespread and native fish in China.They both belong to Cyprinidae,Culterinae,Hemiculter.They have prominent habitat suitability and high invasive potential and are the dominant species in many freshwater ecosystems of our country.But how the 2 species acclimate to extremely heterogeneous environments remains unclear.The morphological difference of 18 different H.leucisculus populations was obtained by geometric morphology.The relationship of morphological and climatic change was then analysized.With mitochondrial gene Cytb,nuclear gene RAG2 and Rho as molecular markers,the genetic structure,genetic diversity and phylogeography of 18 H.leucisculus populations from different drainages were explored.The relationship of morphological difference and genetic differentiation was also discussed preliminarily.In addition,the relationship between the brain volume difference of 8 populations and climatic change was also studied.At the same time the analysis of morphological vatiation from six H.bleekeri populations along Yangtze River basin was conducted.The relationship of their morphological difference and climate change was analysized.Cytb,Rag2 and Rho were emploied as molecular markers to analyze the genetic structure and genetic diversity of the six populations.The relationship between morphological difference and genetic distance of these populations was also explored.The main results are shown as follows:1.The size and shape of H.leucisculus are related to climate,which vary significantly along the latitude and longitude gradient of climate.As to the body size,along the latitude gradient,in high-latitude that is in the northern,the fish is big;along the longitude gradient,fish is bigger from inland and high altitude area than the coastal and low altitude area.But the interactive effect of the climate is more complicated,there is a critical point,on both sides of the point the trend of change is oppositive.The shape of H.leucisculus is also related to climatic gradients.The effect of climatic longitude gradient makes the H.leucisculus body inland narrower than in the coastal area,accompanied by anal fin forward and longer,dorsal fin deepen,backwards and curved,caudal peduncle shorter and volume decreased.Along the longitude gradient,the trend of climatic interaction in the south was different from or on some traits even opposive to the north.Latitude gradient effect makes the H.leucisculus body shorter in the north than in the south,along with the anal fin shorter,caudal peduncle longer and volume larger.The interaction effect along the latitude is stronger inland than in coastal areas.2.The brain or brain components’ volume of H.leucisculus from different populations is significantly associated with climatic change.The result showed that along the latitudinal gradient,just from north to south,the volume of telencephalic lobes,hypothalamus,total brain,cerebellum,and optic tectum decreases.Along the longitude gradient,from coastal to inland,the volume of olfactory bulbs,hypothalamus,cerebellum,and telencephalic lobes increases;there is a critical point on the interaction term along latitude or longitude gradient.On both sides of the point,the trends of climatic effect on the brain and some regions of the brain volume are oppositive.3.Mitochondrial gene Cytb and two nuclear gene RAG2,Rho were used as molecular markers for population genetic diversity,genetic structure and phylogeography analysis of H.leucisculus.According to parameters,H.leucisculus is on a higher level of genetic diversity compared with other fish.The range of genetic differentiation index(F_ST)between populations is wide,which shows that H.leucisculus populations are highly differentiated.The BI phylogenetic tree,haplotype network,STRUCTURE diagram and AMOVA results,although there are some differences between Cytb,RAG2 and Rho,all support the Beihai and Hainan populations differentiating from the others,Beihai and Hainan populations forming the independent evolving lineage.Moreover,the analysis of the genetic structure based on Cytb shows the populations from Yellow River or the Yangtze River drainage gather together resepectively,and supports the two drainage groups have some differentiation too.4.The Mantel test and partial Mantel test were performed between morphological,genetic and climatic distances,results show that the morphological distances between populations are associated with the distances of climate whatever before or after controlling for the genetic factor,which in accord with the previous conclusion of 18 different H.leucisculus populations showing significant morphological variations along the climate latitude and longitude gradient.However,morphological variations have no correlation with genetic differentiations after controlling for climatic factor.Therefore,based on the current sampling range and experimental results,we cannot think that morphological variations have genetic basis.It is speculated that the plasticity caused by climatic change plays important roles in morphological variation.5.The study on the shape and size of 6 populations of H.bleekeri from Yangtze River basin shows changes of shape and size being associated with the climatic longitude gradient.By covariance analysis it is identified that along longitude gradient,the farther inland,the bigger the fish body,and at the same time H.bleekeri developed bigger volume caudal peduncle,shorter anal fin,much streamlined body contour.By the partial least squares analysis,we also make sure the distance to the sea,altitude and annual precipitation contributing greatly to the morphological changes.6.With mitochondrial gene Cytb,two nuclear genes RAG2 and Rho as molecular markers,population genetic diversity,genetic structure and phylogeography of H.bleekeri were studied.Genetic diversity parameters show that H.bleekeri own high diversity.The BI phylogenetic tree and haplotype network indicate no distinct populations gathered geographically,and no obvious branches.The range of genetic differentiation indexes between populations is small which means small population differentiation.STRUCTURE analysis indicates that genetic clusters contributing to each population are similar.AMOVA result suggests the main source of genetic variation comes from within populations.The Mantel test on pairwise F_STs and geographic distances shows that geographical isolation does not exist,and genetic exchange frequently.7.The Mantel test and partial Mantel test were performed on the pairwise distances of morphology,climatic and the genetic variation,the results showe that controlling for the genetic factor or not,morphological variations both associate with climatic changes significantly,which is consistent with the conclusions of covariance analysis and partial least squares.But there is no correlation between morphological differences and genetic variations.A wide span of H.leucisculus sampling was done and the subsequent study on ecological morphology and genetic structure was conducted.Additionally a morphology and phylogenetic study of H.bleekeri of 6 populations from the Yangtze River basin was also carried out.The correlation between morphological variations and climate changes,and correlation between morphological variations and genetic differentiations were analyzed.The important role of plasticity mechanism due to climate gradient in the morphological change was clear out in the research.更多还原