放牧干扰下高原鼢鼠的迁移扩散及对其种群遗传结构的作用

Livestock grazing is one of the most important modes of land use in alpine grassland in Qinghai Tibet Plateau. Overgrazing was thought to facilitate rodent infestations through providing suitable habitats and preferred food. Plateau zokors (Eospalax baileyi) populations were found to increase rapidly with increasing grazing intensity, using their mounds deposited on the surface as an indicator of population density. The succession of the degraded grasslands can be suppressed by the increase in zokor impacts which made the grassland management issues become more prominent. However, causes of populations increase and behavior response patterns of grazing are still unknown. Such information are important for ecologically-based approaches to grassland management. Using 11 polymorphic microsatellite loci we developed recently, mitochondrial markers, and passive integrated transponder(PIT), we aim to explore effects of grassland grazing on zokors population genetic structure and their behavior. Through analysing individual relatedness, and paternity of offspring, we investigate the impact of over grazing on the reproduction, mating system, possible social structure of zokor populations and gene flow between populations by comparing the differences in population genetic variability, genetic structure and gene flow of zokors under different grazing intensities. Such knowledge will allow us to explore the population regulation, inbreeding avoidance and genetic and behavior mechanism in maintaining the plateau zokor population under grazing pressure. The findings of this study will enrich the grassland rodent prevention and control theory, improve the comprehensive prevention and control technology, and provide technical support for the management system of grazing in the grasslands.

青藏高原高寒草地放牧下植被和土壤等发生变化，导致高原鼢鼠（Eospalax baileyi）种群密度增高，加速了草地退化进程。然而除了高原鼢鼠喜食植物增多外，其密度增高的原因并不明确。实践中发现重牧下鼢鼠土丘剧增，但其响应放牧的行为模式等未知。阐明放牧下高原鼢鼠种群密度增高的原因及其维持机制是对其有效防控的关键。本研究在前期研究基础上，拟应用多基因分子标记和PIT标志重捕技术，对高原鼢鼠亲缘关系进行鉴定和追踪，分析放牧对其迁移扩散、配偶选择、生长和繁殖等影响。重点研究扩散和配偶选择对放牧的响应及对其种群遗传结构的作用，探讨放牧下高原鼢鼠扩散和婚配对其遗传结构及基因流影响形成与作用的生态学过程。旨在明确放牧下高原鼢鼠种群密度增高的原因，揭示其近交回避策略及组织方式，阐明放牧下种群维持的行为模式和遗传学机制，丰富与深化草原啮齿动物防控理论，为改进高原鼢鼠综合防控技术，协调放牧管理提供科学依据。

放牧是草地最主要的利用和管理方式，青藏高原高寒草地放牧下植被和土壤等发生变化，加速了草地退化进程，也导致了高原鼢鼠（Eospalax baileyi）种群密度的增高。本项研究于2015-2018年间，对放牧干扰下高原鼢鼠的自然种群进行了监测，分析了高原鼢鼠微栖息环境植被、土壤等特征，放牧扰动下的高原鼢鼠微生境以及放牧作用下高原鼢鼠食性及其营养生态位的变化特征，以及高原鼢鼠扰动对环境的影响作用。测定了高原鼢鼠的社会行为及空间记忆、物体识别等行为基础，并结合多基因分子标记技术分析种群遗传特征和个体之间的亲缘关系，分析了放牧对其迁移扩散、配偶选择、生长和繁殖等影响。研究了扩散和配偶选择对放牧的响应及对其种群遗传结构的作用，以及放牧下高原鼢鼠扩散和婚配对其遗传结构及基因流影响形成与作用的生态学过程。探讨了亲权空间行为对高原鼢鼠种群应对干扰的调节作用，验证了放牧下种群维持的空间亲权行为模式和遗传响应，结果为丰富与深化草原啮齿动物防控理论奠定了基础。