利用景观连续性和居群遗传结构的动态变化来甄别易受生境片段化影响的植物及植物性状

Fragmentation is a process that modifies the landscape by reducing area, increasing isolation, and creating new ecological boundaries. Xishuangbanna is central to one of the World's twenty-five biodiversity hotspots. It is unknown how habitat disturbance to natural populations in Xishuangbanna threatens gene flow mechanisms between fragments of forest trees that differ in their reproductive strategies. It has been hypothesized that trees with larger seeds dispersed by large mammals have relatively poor propagule dispersal ranges compared to species with smaller seeds dispersed by birds or wind. Poor dispersal ability between fragments can reduce genetic diversity within populations and result in increased extinction risk. Assessing the genetic structuring of species that differ in their reproductive strategies is critical to the implementation of sound policy criteria for managing ecosystem services. Yunnan Province and in particular Xishuangbanna is subject an unprecedented expansion of rubber plantations. Rubber plantations are replacing traditional landuse forms and negatively impacting on biodiversity-dependent resources such as tradition medicine, reservoirs of genetic diversity of economically important species, tourism, and research and development in general. The replacement of regions of high biodiversity with monocultures of rubber disrupt energy, water, and carbon cycles that result in land-quality degradation, and in extreme cases, desertification. The tolerances different species have to landscape fragmentation at various intensities are uncertain. It is unclear what types of species are most threatened by changes to traditional landuse practices. This project proposes the identification of particular functional groups of species that are most at risk of extinction resulting from sustainable high-intensity agricultural practices such as rubber cultivation. Population genomic approaches will be used to evaluate the level of gene flow in age categories of different species between fragments. Ecological field techniques will be used to identify candidate species that differ in their life history strategies and determine age categories within fragments. Next generation sequencing approaches will be used to quantify spatial genetic structuring of species within and among fragments. Evaluation of genetic structuring between age categories within a species will provide estimates of the influence fragmentation has on gene flow. We expect the youngest cohort to be most susceptible to decreased gene flow and diversity because older cohorts were not subject to as severe landscape fragmentation. Additionally, we expect that species with larger seeds will be most susceptible to a reduction in propagule dispersal and genetic diversity within fragments.

西双版纳是世界25个生物多样性热点之一，但橡胶种植正在取代传统的土地利用方式，显著的改变景观格局，热带雨林面积减少并被分割成斑块状，这一进程对生物多样产生负面影响，同时多种多样的生物资源面临灭绝的可能，我们急需研究在持续高强度橡胶种植影响下物种功能性灭绝的鉴定方法。据推测，和由鸟类或者风传播种子的物种相比，由哺乳动物传播种子的物种具有较小的后代分布范围，我们推测其可能更容易受到片段化的影响而面临灭绝的危险。值得一提的是，片段化影响的只是新生个体的遗传多样性，而残存的个体没有受到影响。结合生活史，我们将选取多物种，使用基因组学和下一代测序技术，比较不同年龄群，研究它们的空间遗传结构，分析斑块内和斑块间的基因流，以此来鉴定容易受到片段化影响的物种。本项目的开展将探明生活史和景观格局如何影响基因流，并对生物多样性的管理和保护提供理论指导作用。

西双版纳作为世界上25个最具生物多样性的地区之一，正遭受各种人为活动的威胁。截至2003年，其森林覆盖率已经较1976年下降了28%，但与此同时，单就橡胶种植一项却扩增了90%。虽然就目前所知，农业扩张和强化对节肢动物的影响是有限的，但是它为粮食安全和生物多样性对于管理和服务生态系统的重要性提供了一个参考和新认识。单一栽培正在迅速取代其他传统的土地利用形式，这对生态过程、能源、水份和碳平衡的影响是毁灭性和不可预知的。为了减轻授粉其潜在损失的影响，关于生物控制和入侵，以及农业集约化和扩张对自然群落适应能力的影响的认识是有必要的。节肢动物在生态系统中起着十分重要的运用，其并已被广泛运用于监测环境的变化。然而，评估节肢动物生物多样性的传统方法，不仅昂贵，而且费时，更需要专业的知识，且难以规范化。Metabarcoding因其具有更全面快速、可审计和较少依赖分类技术这些优点，可用于作为生物多样性保护和生态系统管理的一个强大工具。这是一个快速监测生物多样性的方法，其集成了DNA分类学和高通量DNA测序。这里我们展示了在分析各类农业扩张的影响及在节肢动物多样性实践方面的新技术，讨论了如何使用这些技术来测量生物多样性的变化和信息管理的价值。.