Diversity, speciation, endemism and extinction in Devonian reef and level-bottom communities, eastern North America
Diversity, speciation, endemism and extinction in Devonian reef and level-bottom communities, eastern North America
复制标题
北美东部泥盆纪珊瑚礁和平底群落的多样性、物种形成、特有现象和灭绝
作者：
J. A. Fagerstrom
下泥盆世晚期埃姆斯（博伊斯布兰克和清溪石灰岩; Schoharie组）水平底部社区在纽约，密歇根州和伊利诺伊州适度世界性和多样性，并占主导地位的腕足动物和孤独的皱纹珊瑚。早期Eifelian（英语：Early Eifelian）在纽约（Edgecliff Member，Onondaga石灰岩）、安大略西南部（福尔摩沙礁石灰岩，下底特律河群）和哈德逊湾低地（Kwataboahegan Formation），有一个重要的由高度多样化的地方性群落组成的珊瑚礁斑块形成的事件。Edgecliff礁是由珊瑚建造的，而福尔摩沙和Kwataboahegan礁主要是由层孔虫建造的。高多样性和高特有性之间的强相关性，在造礁事件表明，这些社区包含了许多，小物种种群属于几个主要类群-一个例子，快速物种形成的地理隔离和遗传漂变。
Lower Devonian late Emsian (Bois Blanc and Clear Creek Limestones; Schoharie Formation) level-bottom communities in New York, Michigan and Illinois were moderately cosmopolitan and diverse and dominated by brachiopods and solitary rugose corals. Subsequently (Early Eifelian?), there was an important episode of cratonal patch reef building in New York (Edgecliff Member, Onondaga Limestone), southwestern Ontario (Formosa Reef Limestone, lower Detroit River Group), and the Hudson Bay Lowland (Kwataboahegan Formation) by highly diverse endemic communities. The Edgecliff reefs were built by corals whereas the Formosa and Kwataboahegan reefs were built primarily by stromatoporoids. The strong correlation between high diversity and high endemism during the reef-building episode suggests that these communities contained numberous, small species populations belonging to several major taxa — an example of rapid speciation by geographic isolation and genetic drift.