Geographic range size and abundance are important determinants of extinction risk in fossil and extant taxa. However, the relationship between these variables and extinction risk has not been tested extensively during evolutionarily “quiescent” times of low extinction and speciation in the fossil record. Here we examine the influence of geographic range size and abundance on extinction risk during the late Paleozoic (Mississippian–Permian), a time of “sluggish” evolution when global rates of origination and extinction were roughly half those of other Paleozoic intervals. Analyses used spatiotemporal occurrences for 164 brachiopod species from the North American midcontinent. We found abundance to be a better predictor of extinction risk than measures of geographic range size. Moreover, species exhibited reductions in abundance before their extinction but did not display contractions in geographic range size. The weak relationship between geographic range size and extinction in this time and place may reflect the relative preponderance of larger-ranged taxa combined with the physiographic conditions of the region that allowed for easy habitat tracking that dampened both extinction and speciation. These conditions led to a prolonged period (19–25 Myr) during which standard macroevolutionary rules did not apply.

中文翻译：

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在“缓慢”进化时期地理范围大小和丰度对灭绝的影响

地理范围的大小和丰度是化石和现存分类群灭绝风险的重要决定因素。然而，在化石记录中低灭绝和物种形成的进化“静止”时期，这些变量与灭绝风险之间的关系尚未得到广泛测试。在这里，我们研究了古生代晚期（密西西比-二叠纪）地理范围大小和丰度对灭绝风险的影响，这是一个“缓慢”演化的时期，全球起源和灭绝的速度大约是其他古生代间隔的一半。分析使用了来自北美中部大陆的 164 种腕足类动物的时空事件。我们发现丰度比地理范围大小的测量值更能预测灭绝风险。而且，物种在灭绝前表现出丰度减少，但地理范围大小没有收缩。在这个时间和地点，地理范围大小与灭绝之间的弱关系可能反映了较大范围分类群的相对优势以及该地区的自然地理条件，这使得栖息地追踪变得容易，从而抑制了灭绝和物种形成。这些条件导致标准宏观进化规则不适用的长时间（19-25 Myr）。在这个时间和地点，地理范围大小与灭绝之间的弱关系可能反映了较大范围分类群的相对优势以及该地区的自然地理条件，这使得栖息地追踪变得容易，从而抑制了灭绝和物种形成。这些条件导致标准宏观进化规则不适用的长时间（19-25 Myr）。在这个时间和地点，地理范围大小与灭绝之间的弱关系可能反映了较大范围分类群的相对优势以及该地区的自然地理条件，这使得栖息地追踪变得容易，从而抑制了灭绝和物种形成。这些条件导致标准宏观进化规则不适用的长时间（19-25 Myr）。