Recent evidence has questioned whether the Latitudinal Diversity Gradient (LDG), whereby species richness increases towards the Equator, results in higher rates of speciation in the tropics. Allowing for time heterogeneity in speciation rate estimates for over 60,000 angiosperm species, we found that the LDG does not arise from variation in speciation rates because lineages do not speciate faster in the tropics. These results were consistently retrieved using two other methods to test the association between occupancy of tropical habitats and speciation rates. Our speciation rate estimates were robust to the effects of both undescribed species and missing taxa. Overall, our results show that speciation rates follow an opposite pattern to global variation in species richness. Greater ecological opportunity in the temperate zones, stemming from less saturated communities, higher species turnover or greater environmental change, may ultimately explain these results.

中文翻译：

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被子植物的物种形成在热带地区冷却下来。

最近的证据质疑纬度多样性梯度（LDG），即物种丰富度向赤道增加，是否导致热带地区物种形成率更高。考虑到超过 60,000 种被子植物物种形成率估计的时间异质性，我们发现 LDG 不是由物种形成率的变化引起的，因为谱系在热带地区的物种形成速度并不快。使用其他两种方法始终如一地检索这些结果，以测试热带栖息地的占有率与物种形成率之间的关联。我们的物种形成率估计对未描述物种和缺失分类群的影响是稳健的。总体而言，我们的结果表明，物种形成率遵循与物种丰富度的全球变化相反的模式。温带地区更大的生态机会，