关键词: 青藏高原, 繁殖分配, 性分配, 克隆繁殖, 有性繁殖, 花部特征演化

Abstract:

The Qinghai-Xizang Plateau and its adjacent highlands host a rich plant diversity, and understanding on how plant species reproduce successfully in those high mountain regions would be of great help for us to discover the evolution and adaptability of plants to the typical alpine environments. Here, we reviewed the progresses of plant reproductive ecology in the Qinghai-Xizang Plateau and its adjacent highlands, with emphases on resource allocation, reproductive mode, evolution of floral traits, etc. We also summarized the impacts of global climate changes on plant reproduction, and the applications of new technologies and methods in this research field to explore the potential mechanisms of plant evolution and adaptation. In the stressful environments of high mountain areas, with the increase of altitude, the reproductive allocation usually shows a trend of increase, and the proportion of resources invested in male function also increases. However, the specific pattern of resource allocation strongly depends on the mating system, individual size, life history, genetic variation and resource availability. In the context of resource and pollination limitation, plants will weight different reproductive modes. Clonal reproduction and self-pollination are conductive to reproductive assurance in populations with pollinator scarcity, while sexual reproduction and cross-pollination can improve seed quality and genetic diversity of offspring, which could benefit population survival in the potential climate flunctations. Therefore, the combinations of different reproductive modes and the generalized pollination networks may be the good choices to adapt to the stressful environments of highlands. The evolution of floral traits might be mainly driven by the selective pressure of local pollinators, but more and more attentions have been paid to the effects of exotic pollinators, herbivores, nectar robbers and abiotic environments such as temperature, precipitation and ultraviolet radiation on floral traits. In recent years, the Qinghai-Xizang Plateau has become one of research hotspots because of its fragility and sensitivity to climate change. Global climate change, characterized by global warming and increased nitrogen deposition, is directly or indirectly affecting the reproductive characteristics of plant species in the region. Climate change may cause shifts of phenology and distribution area of plants and pollinators, which leads to temporal decoupling and spatial mismatch between them. Plants can respond to climate change by adjusting floral traits (floral display, corolla structure, quantity and quality of reward), which may result in changes of type, amount and foraging behaviors of pollinators and affect reproductive success of plants at last. The applications of new technologies and methods could advance our knowledge on plant reproductive ecology. 3D printed flowers could control floral traits precisely and could be employed in examining the effects of subtle changes of floral traits on pollinator behaviors, which would be useful in understanding pollinator mediated selection on floral traits in combination with the uses of commercial pollinators. Importantly, with the development of high-throughput sequencing, the underlying mechanisms of important topics in plant reproductive ecology could be discovered more easily than before, especially in the field of floral evolution. As a conclusion, key issues that need additional attention in the current research as well as the fields worthy of further study are highlighted.

Key words: Qinghai-Xizang Plateau, reproductive allocation, sexual allocation, clonal reproduction, sexual reproduction, floral evolution