Reproductive strategies of animal-pollinated plants on high mountains: A review of studies from the Third Pole

Having hundreds of big mountains, the Qinghai-Tibetan Plateau and its southern boundary, the Hengduan Mountains Region, represent one of the world's biodiversity hotspots. In the so-called Third Pole of the earth, diverse effects of climate change and habitat heterogeneity could have driven the evolution of plant adaptive strategies. In this review, we collected and compiled recent sources of reproductive biology in animal-pollinated plants, stressing the questions that need further attention, including pollination system, pollen limitation, self-compatibility, and sexual system. We constructed plant-pollinator interaction networks based on the case studies from this region, showing that the majority of pollinators were bees, moths, butterflies, and flies were also important, and bats and birds were rare. As the unpredictable (cold, rainy or windy) weather affects pollinator activities, sexual reproduction seemed to be pollen limited, but available studies show that the exact pattern of pollen limitation is still under debate. Self-compatibility could be either a solution, or a result from pollen limitation. Moreover, plant sexual systems can be regarded as an integrated module that counters pollen limitation. As phylogenetic relationships were constructed, diverse genera experienced rapid radiation were revealed in these mountainous areas. Further studies of evolutionary transitions in reproductive systems of congeners will unveil potential factors shaping the general pattern of adaptive strategies in animal-pollinated plants. Further studies will be beneficial in using advanced new techniques, examining phenotypic selection under common gardens, and considering chemical ecology in interactions between plants and florivores, particularly in pollen fate.

Automated summary

The Qinghai-Tibetan Plateau and the Hengduan Mountains Region are biodiversity hotspots, where climate change and habitat heterogeneity may have influenced the evolution of plant adaptive strategies. Through studying plant-pollinator interactions, it was found that bees were the main pollinators, with factors such as pollen limitation and self-compatibility impacting plant adaptive strategies.