PDF(Pubmed)
Abstract：
OBJECTIVE: The quartz fields of the Greater Cape Floristic Region (GCFR) are arid and island-like special habitats, hosting ~142 habitat-specialized plant species, of which 81 % are local endemics, characterized by a rapid turnover of species between and among sites. We use several phylogenetic community metrics: (1) to examine species diversity and phylogenetic structure within and among quartz fields; (2) to investigate whether quartz field specialists are evolutionarily drawn from local species pools, whereas the alternative hypothesis posits that there is no significant evolutionary connection between quartz field specialists and the local species pools; and (3) to determine whether there is an association between certain traits and the presence of species in quartz fields.
METHODS: We sampled and developed dated phylogenies for six species-rich angiosperm families (Aizoaceae, Asteraceae, Crassulaceae, Cyperaceae, Fabaceae and Santalaceae) represented in the quartz field floras of southern Africa. Specifically, we focused on the flora of three quartz field regions in South Africa (Knersvlakte, Little Karoo and Overberg) and their surrounding species pools to address our research questions by scoring traits associated with harsh environments.
RESULTS: We found that the Overberg and Little Karoo had the highest level of species overlap for families Aizoaceae and Fabaceae, whereas the Knersvlakte and the Overberg had the highest species overlap for families Asteraceae, Crassulaceae and Santalaceae. Although our phylogenetic community structure and trait analyses showed no clear patterns, relatively low pairwise phylogenetic distances between specialists and their local species pools for Aizoaceae suggest that quartz species could be drawn evolutionarily from their surrounding areas. We also found that families Aizoaceae and Crassulaceae in Knersvlakte and Little Karoo were phylogenetically even.
CONCLUSIONS: Despite their proximity to one another within the GCFR, the studied areas differ in their species pools and the phylogenetic structure of their specialists. Our work provides further justification for increased conservation focus on these unique habitats under future scenarios of global change.
METHODS: We sampled and developed dated phylogenies for six species-rich angiosperm families (Aizoaceae, Asteraceae, Crassulaceae, Cyperaceae, Fabaceae and Santalaceae) represented in the quartz field floras of southern Africa. Specifically, we focused on the flora of three quartz field regions in South Africa (Knersvlakte, Little Karoo and Overberg) and their surrounding species pools to address our research questions by scoring traits associated with harsh environments.
RESULTS: We found that the Overberg and Little Karoo had the highest level of species overlap for families Aizoaceae and Fabaceae, whereas the Knersvlakte and the Overberg had the highest species overlap for families Asteraceae, Crassulaceae and Santalaceae. Although our phylogenetic community structure and trait analyses showed no clear patterns, relatively low pairwise phylogenetic distances between specialists and their local species pools for Aizoaceae suggest that quartz species could be drawn evolutionarily from their surrounding areas. We also found that families Aizoaceae and Crassulaceae in Knersvlakte and Little Karoo were phylogenetically even.
CONCLUSIONS: Despite their proximity to one another within the GCFR, the studied areas differ in their species pools and the phylogenetic structure of their specialists. Our work provides further justification for increased conservation focus on these unique habitats under future scenarios of global change.
摘要：
目的：大开普植物区系（GCFR）的石英田是干旱和岛屿状的特殊栖息地，拥有大约142种栖息地专用植物，其中81％是当地特有的，以地点之间物种的快速周转为特征。我们使用几种系统发育群落指标来i）检查石英场内和之间的物种多样性和系统发育结构；ii）调查石英领域专家是否从当地物种库中进化，而替代假设认为，石英领域专家与当地物种库之间没有显着的进化联系；iii）确定某些特征与石英领域中物种的存在之间是否存在关联。
方法：我们对六个物种丰富的被子植物科（Aizoaceae，菊科,景天科,莎草科,豆科和桑塔尔科）在南部非洲的石英田植物区系中代表。具体来说,我们专注于南非三个石英场地区的植物区系(Knersvlakte，LittleKaroo和Overberg）及其周围的物种池来解决我们的研究问题，与恶劣环境相关的评分特征。
结果：我们发现Overberg和LittleKaroo在Aizoaceae和Fabaceae中具有最高的物种重叠水平，而Knersvlakte和Overberg的菊科物种重叠最高，景天科,和桑塔尔科。尽管我们的系统发育群落结构和性状分析没有显示出明确的模式，Aizoaceae和Fabaceae的专家与其当地物种库之间的成对系统发育距离相对较低，这表明石英物种可以从其周围地区进化中提取，在Knersvlakte和LittleKaroo中，Aizoaceae和Crassulaceae具有系统发育过度分散。
结论：尽管它们在GCFR中彼此接近，研究区域的物种库和专家的系统发育结构不同。我们的工作为在未来全球变化的情况下增加对这些独特栖息地的保护重点提供了进一步的理由。
方法：我们对六个物种丰富的被子植物科（Aizoaceae，菊科,景天科,莎草科,豆科和桑塔尔科）在南部非洲的石英田植物区系中代表。具体来说,我们专注于南非三个石英场地区的植物区系(Knersvlakte，LittleKaroo和Overberg）及其周围的物种池来解决我们的研究问题，与恶劣环境相关的评分特征。
结果：我们发现Overberg和LittleKaroo在Aizoaceae和Fabaceae中具有最高的物种重叠水平，而Knersvlakte和Overberg的菊科物种重叠最高，景天科,和桑塔尔科。尽管我们的系统发育群落结构和性状分析没有显示出明确的模式，Aizoaceae和Fabaceae的专家与其当地物种库之间的成对系统发育距离相对较低，这表明石英物种可以从其周围地区进化中提取，在Knersvlakte和LittleKaroo中，Aizoaceae和Crassulaceae具有系统发育过度分散。
结论：尽管它们在GCFR中彼此接近，研究区域的物种库和专家的系统发育结构不同。我们的工作为在未来全球变化的情况下增加对这些独特栖息地的保护重点提供了进一步的理由。
