Molecular Phylogeny of Myricaria (Tamaricaceae): Implications for Taxonomy and Conservation in China

水柏枝屬隸屬於檉柳科共包含約13個物種，其中10種分佈於中國。該屬植物多爲河邊或湖邊灌木，以喜馬拉雅地區爲分佈中心並覆蓋從東亞到中亞和歐洲的廣泛地區。隨著不斷增加的人爲干擾例如築壩、修路和過度放牧等導致的生境片斷化加劇，中國大多水柏枝植物的生存狀態受到極大威脅。分析水柏枝屬植物的分子系統關係對於理解它們的分類並制定正確的保育措施具有重要作用。本文利用核基因組ITS序列和葉綠體基因組psbA和trnH基因間序列資訊分析水柏枝屬植物的分子系統關係，並和形態關係進行比較研究。分子系統樹顯示秀麗水柏枝是最基部的進化支系。同時，分子分析解決了一個形態學分類困難標本的系統分類歸屬問題即作爲小花水柏枝的生態變型，並建立了三個形態近緣種三春水柏枝、寬苞水柏枝和具鱗水柏枝間的分子系統關係。雖然心葉水柏枝和寬葉水柏枝的形態特徵更接近於秀麗水柏枝，但分子分析表明它們同前面三個形態近緣種更加的近緣；類似的，疏花水柏枝也表現了分子和形態關係的差異，即其具有較古老的分子系統發育但形態上類似於三春水柏枝。我們的系統分析支援水柏枝屬植物的喜馬拉雅起源和進化中心假說。基於本分子系統分析，相關物種的保育地位得到了討論。

關鍵字

保育；形態學；水柏枝屬；系統發育；檉柳科；分類學

並列摘要

The genus Myricaria belongs to the family Tamaricaceae, which consists of thirteen species, ten of which are distributed in China. They are riparian or lake-side shrubs and naturally occur in eastern Asia, extending to central Asia and Europe, with a suggested center of origin and diversity in the Himalayan region. Most of the species are threatened by increasing habitat fragmentation and anthropogenic disturbances like dam and highway construction and over-grazing. Information on molecular phylogenetic relationships is critical for understanding the taxonomy and developing conservation strategies for Myricaria species in China. In the present study, DNA sequence data from the nuclear ribosomal internal transcribed spacer region and the plastid psbA-trnH intergenic spacer were used to infer the phylogeny of the genus. Thirteen morphological traits were also used in conjunction with the molecular phylogenetic relationships. The phylogenetic analysis revealed a basal clade of M. elegans to other Myricaria species. Molecular evidence resolved one suspicious specimen Myricaria sp. that was closely related to M. wardii. Furthermore, the results revealed that three widespread species—M. paniculata, M. bracteata and M. squamosa-with little morphological difference have distinct DNA sequences. On the other hand, M. pulcherrima and M. platyphylla were found to be grouped with the above three widespread species despite their morphological characters being similar to that of M. elegans. Also, M. laxiflora was found in a more basal phylogenetic position than M. paniculata although the two species are morphologically similar. Our phylogenetic analyses provided molecular evidence in supporting the hypothesis that the center of origin and evolution for Myricaria species is the Himalayan region. The present study provides useful baseline data for formulating conservation priorities and further taxonomic delineation.

並列關鍵字

Conservation ； Morphology ； Myricaria ； Phylogeny ； Tamariacaceae ； Taxonomy

國際替代計量

Molecular Phylogeny of Myricaria (Tamaricaceae): Implications for Taxonomy and Conservation in China

全文下載

主題瀏覽