Complexity responses of Rhododendron species to climate change in China reveal their urgent need for protection

Global climate change has been widely recognized as important factors that threaten biodiversity.Rhododendron species are not only famous woody ornamental plants worldwide but are also indispensable components in alpine and subalpine vegetation in southwest China.However,the geographical distribution ranges response of this broad taxonomic group to future climate change remains not be fully understood.Herein,we studied the impact of climate change on the distribution of Rhododendron species in China by predicting the changes in their suitable habitats,centroid,and species richness under three climate change scenarios(SSP1-2.6,SSP2-4.5 and SSP5-8.5)in the 2090s.The species richness changes of Rhododendrons along altitude were also evaluated.In addition,we calculated the phylogenetic signals of distribution response to climate change.We found that the distribution responses of Rhododendron to climate change have weak phylogenetic signals.In the 2090s,the suitable habitats of about 87%of Rhododendron species will be reduced,77%of Rhododendron species are manifested as northward migration.The high species richness of Rhododendrons tends to migrate to transboundary areas with high altitudes in China.Some Rhododendron species with no concern previously should be taken seriously for their high risk of habitat loss under climate change.Thus,the urgent protection of Rhododendron species under climate change need to be paid more attention than previous acknowledged.We recommend carrying out the reintroduction of endangered species in future suitable habitat,strengthening the protection of transboundary areas with high species richness,and focusing on species with few concerns previously.

复方血栓通胶囊对高海拔视网膜病变大鼠的保护作用

目的:探讨复方血栓通胶囊对高海拔视网膜病变大鼠的保护作用及其作用机制。方法:雄性SD大鼠24只随机分为6组,分别饲养于模拟高海拔5000m的高原舱内2、4、6、10、24、72h,观察各组大鼠视网膜组织形态,HIF-1α的表达和入舱前后大鼠视网膜电图中暗适应最大反应b波振幅的变化;雄性SD大鼠24只随机分为4组,分别予安慰剂,大花红景天口服液,肌苷片及复方血栓通胶囊灌胃喂药7d后,饲养于模拟海拔为5000m模拟舱内10h,观察各组大鼠视网膜组织形态,HIF-1α的表达和入舱前后大鼠视网膜电图中暗适应最大反应b波振幅的变化。结果:高海拔视网膜病变SD大鼠模型中,结果显示随着各实验时间的增加,神经节细胞层细胞肿胀明显,HIF-1α在神经节细胞及内核层细胞胞浆表达增高,均在10h时最为明显。各组SD大鼠进舱自身前后F-ERG暗适应最大反应b波振幅变化分析,4、6、10、72h组F-ERG暗适应最大反应b波振幅显著降低(P<0.05);2h组和4h组(P=0.007)、6h组(P=0.008)、10h(P=0.002)有差异,24h组和4h组(P=0.035)、6h(P=0.040)、10h组(P=0.012)有差异。复方血栓通对SD大鼠高海拔视网膜病变预防作用研究中,结果显示与安慰剂组相比较,复方血栓通组、红景天组及肌苷组的视网膜水肿均明显减轻,但复方血栓通组与红景天组视网膜水肿程度明显低于肌苷组;复方血栓通组及红景天组HIF-1α在神经节细胞层及内核层表达明显下降;各组SD大鼠进舱后F-ERG暗适应最大反应b波振幅比较显示,安慰剂组与复方血栓通组(P=0.032),红景天组(P=0.001)均有差异。结论:在模拟高海拔环境下,复方血栓通可能是通过抑制HIF-1α的表达对大鼠高海拔视网膜病变有保护作用,但是具体作用机制有待我们进一步研究。