热带亚热带深水水库盔型溞遗传多样性的季节变化与空间异质性

The genetic diversity and spatio-temporal patterns of genetic structure in cladoceran population is a foundation for preserving and maintaining their species diversity in freshwater bodies. Usually, we always assume that the genetic structure in small scale of spatio-temporal populations in a given water body is homogeneous if the genetic information is not available. But in a large and deep water body, especially those reservoirs in tropical and subtropical regions with structured habitats and strong predation pressure might lead to a remarkable spatial and temporal heterogeneity of genetic structure in cladoceran populations, and the heterogeneity consequently impacts the maintained mechanisms of the genetic diversity and subpopulations of cladoceran. The present study will focus on a large water flea, Daphnia galeata which widely distributes in the world and China. We will use the information of COI sequence and microsatellite DNA to detect the genetic variation in seasonal populations and spatial patterns in four typical large and deep reservoirs in tropical and subtropical regions.We will investigate the genetic structure of Daphnia galeata population in small spatial scale, and seasonal patterns affected by clonal erosion over seasons. We integrate the environmental variables linking with selection pressure, population abundance and genetic structure to demonstrate the driving force of population differentiation of Cladocera in large and deep tropical and subtropical reservoirs.

枝角类种群的遗传多样性及时空变化特征是其在自然水体中多样性的保存和维持机制的重要基础。在缺少遗传信息时，通常假定同一水体中，时间和空间上种群在遗传结构上是同质的。但在大型水体，特别是热带亚热带地区，生境分区与较强捕食压力有可能导致枝角类遗传结构的空间与时间异质性，从而影响枝角类多样性和种群维持。本项目将以我国广泛分布的大型枝角类Daphnia galeata为对象，通过COI基因序列和微卫星分子标记的测定和分析，了解热带亚热带地区深水水库Daphnia galeata遗传多样性及遗传结构在水体空间上的分布特征和季节变化，分析大型枝角类种群结构在水体内时间和空间小尺度上的异质性以及种群遗传多样性季节性侵蚀特征，结合水体环境因子和大型枝角类种群数量变化，揭示环境因子、种群数量以及种群遗传结构之间的关系，阐明热带亚热带水体中大型枝角类种群分化的潜力。

枝角类种群的遗传多样性及时空变化特征是其在自然水体中多样性的保存和维持机制的重要基础。本研究以大型枝角类Daphnia galeata为对象，利用线粒体与微卫星标记，研究空间种群遗传结构与热带亚热带深水水库中种群遗传结构的季节变化。在广东流溪河水库连续4年对D. galeata种群遗传结构观测与分析发现，期望杂合度为0.306 - 0.546，共有多位点基因型在不同年份中都有发现，遗传结构在连续4年的逐月采集种群中存在明显变化，整个生长季节过程中，D. galeata种群遗传多样性没有明显的逐步下降过程，而呈现断崖式下降，说明不存在缓慢的克隆侵蚀过程，而呈现出较强的克隆选择作用。休眠卵库和克隆选择共同决定了D. galeata现生种群的遗传多样性和遗传结构。同一水库的不同区域，遗传多样性也存在较大差异，生长季节初期库中和大坝的遗传多样性高于水库其他区域，而在生长季节末期，库中遗传多样性最高。