High speciation rate at temperate latitudes explains unusual diversity gradients in a clade of ectomycorrhizal fungi

Understanding the patterns of biodiversity through time and space is a challenging task. However, phylogeny-based macroevolutionary models allow us to account and measure many of the processes responsible for diversity build-up, namely speciation and extinction. The general latitudinal diversity gradient (LDG) is a well-recognized pattern describing a decline in species richness from the equator pole-wards. Recent macroecological studies in ectomycorrhizal (EM) fungi have shown that their LDG is shifted, peaking at temperate rather than tropical latitudes. Here we investigate this phenomenon from a macroevolutionary perspective, focusing on a well-sampled group of edible EM edible mushrooms from the genus Amanita –the Caesar's mushrooms, which follow similar diversity patterns. Our approach consisted in applying a suite of models including: (1) non-trait-dependent time-varying diversification (BAMM), (2) continuous trait-dependent diversification (QuaSSE), and (3) diversity-dependent di...

理解生物多样性在时空维度上的分布模式是一项极具挑战性的任务。然而，基于系统发育的宏观进化模型（phylogeny-based macroevolutionary models）能够帮助我们解析并量化诸多驱动多样性形成的核心过程，即物种形成与灭绝。普遍存在的纬度多样性梯度（latitudinal diversity gradient, LDG）是一项被广泛认可的分布模式，其描述了物种丰富度从赤道向两极逐渐降低的规律。近期针对外生菌根（ectomycorrhizal, EM）真菌的宏观生态学研究表明，这类真菌的纬度多样性梯度发生了偏移，其物种丰富度峰值出现在温带纬度带而非热带纬度带。本研究从宏观进化视角对这一现象展开探究，聚焦于鹅膏属（Amanita）中一组采样充分的可食用外生菌根蘑菇——凯撒蘑菇（Caesar's mushrooms），这类真菌同样呈现出类似的多样性分布模式。我们的研究方法涵盖了一系列模型，包括：(1) 非性状依赖的时变多样化模型（BAMM）、(2) 连续性状依赖的多样化模型（QuaSSE）以及(3) 依赖多样性的……