Journal of Systematics and Evolution最新文献

The big-bracted dogwood clade Benthamidia of Cornus is a typical example of the well-known eastern Asia (EA) and North America (NA) floristic disjunction, with greater species diversity in EA than in NA. The lineage provides an opportunity to explore factors contributing to the plant diversity unevenness between EA and NA and test hypotheses on the origin of disjunct distribution from a phylogenetic perspective. We generated RAD-seq data, conducted phylogenomic and biogeographic analyses for the clade with sampling of all species (9) and subspecies (10) currently recognized in floras. We also assessed species delineation and calculated phylogenetic diversity to evaluate the diversity unevenness between EA and NA. Finally, we examined variation of diversification rates and ecological niches on the phylogeny to explore potential causes underlying the observed diversity pattern. Our results revealed phylogenetic relationships congruent with previous studies and suggested a trans-Beringian ancestral distribution of the clade Benthamidia in the mid-Oligocene, dispersal from Mexico to eastern United States in the mid-Miocene, and early diversification of the EA clade in SW China. Our results also confirmed greater phylogenetic diversity and diversification rate of the EA clade. Species delimitation analysis suggested 17 species in the clade Benthamidia, including all recognized subspecies. By integrating the results of molecular data with morphology, we proposed to retain the subspecies without changing their ranks. Our data suggested increased diversification rate in EA as an intrinsic factor explaining the greater species diversity in the region driven mainly by biogeographic isolation and partially by niche divergence.

At the XIX International Botanical Congress held in Shenzhen, China, in July 2017, the delegates unanimously adopted the Shenzhen Declaration on Plant Sciences in an effort to accelerate the contributions made by plant scientists for the benefit of the world′s changing society. This paper discusses what has been accomplished concerning plant conservation since the Shenzhen Declaration. Beyond the problems we faced in 2017, the global Covid pandemic and the war have presented new challenges. With the massive ecological overshoot, the number of malnourished people globally has increased. Most threats to vascular plants have increased generally over these 6 years, while the responses of the botanical community to them have continued to proceed at a relatively slow pace. Although international cooperation is needed to combat the grave challenges we face, the ease of such collaboration has decreased substantially in recent years. Certainly, rapid deforestation, especially in the tropics, and our ineffective approaches to mitigate climate change will lessen the effectiveness of our strategies to slow extinction. Indeed, our blindness to the reality of ecological overshoot and misperceptions concerning sustainability are accelerating extinction and thus destabilizing social structures and civilization. As an example, conservation in China faces serious challenges with biodiversity loss, but botanical gardens and seed banks there offer hope on ex situ conservation. The botanical and other scientific communities can contribute by drawing the attention of fellow citizens to the gravity of the problems that we face and by being actively engaged in providing solutions and carrying them forward to action.