The opening of habitats associated with the emergence of C₄ grasslands during the Neogene had a massive influence on the evolution of plant and animal communities. Strikingly, the impacts of grassland expansion on species diversification in Africa, where the largest surface of grasslands and savannas in the world is located, are not well understood. To explore the impact of habitat opening, we investigate the evolution of noctuid stemborers, a group of moths mostly associated with open habitats, and whose diversity is centered in the Afrotropics. We generate a dated molecular phylogeny for ca 80% of the known stemborer species, and assess the role of habitat opening on the evolutionary trajectory of the group through a combination of parametric historical biogeography, ancestral character state estimation, life history traits and habitat-dependent diversification analyses. Our results support an origin of stemborers in Southern and East Africa ca 20 million years ago (Ma), with range expansions linked to the increased availability of open habitats to act as dispersal corridors, and closed habitats acting as potent barriers to dispersal. Early specialization on open habitats was maintained over time, with shifts towards closed habitats being rare and invariably unidirectional. Analyses of life history traits showed that habitat changes involved specific features likely associated with grassland adaptations, such as variations in larval behavior and color. We compare these findings to those previously inferred for an Afrotropical butterfly group that diversified roughly in parallel with the stemborers but distributed predominantly in closed habitats. Remarkably, these two groups show nearly opposite responses in relation to habitat specialization, whether in terms of biogeographical patterns, or in terms of rates of transition between open and closed habitats. We conclude that habitat opening played a major role in the evolutionary history of Afrotropical lineages through dispersal and adaptation linked to habitat shifts.

中文翻译：

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栖息地开放促进了多样性：分布和栖息地转移对非洲热带昆虫群进化史的影响


新近纪期间与C ₄草原的出现相关的栖息地开放对动植物群落的进化产生了巨大影响。引人注目的是，非洲拥有世界上面积最大的草原和稀树草原，但草原扩张对物种多样化的影响尚不清楚。为了探索栖息地开放的影响，我们研究了夜蛾类的进化，这是一群主要与开放栖息地相关的蛾类，其多样性集中在非洲热带地区。我们为大约 80% 的已知茎蛀虫物种生成了过时的分子系统发育，并通过参数历史生物地理学、祖先特征状态估计、生活史特征和栖息地依赖的组合来评估栖息地开放对该群体进化轨迹的作用。多元化分析。我们的研究结果支持茎蛀虫起源于大约2000万年前（Ma）的南部和东部非洲，其范围的扩大与开放栖息地的增加有关，这些开放栖息地可作为扩散走廊，而封闭的栖息地则可作为扩散的有效障碍。随着时间的推移，早期对开放栖息地的专业化得以维持，向封闭栖息地的转变很少且总是单向的。对生活史特征的分析表明，栖息地的变化涉及可能与草原适应相关的特定特征，例如幼虫行为和颜色的变化。我们将这些发现与之前推断的非洲热带蝴蝶群体的发现进行了比较，该群体的多样性与茎蛀虫大致平行，但主要分布在封闭的栖息地。 值得注意的是，无论是在生物地理模式方面，还是在开放和封闭栖息地之间的过渡率方面，这两个群体在栖息地专业化方面表现出几乎相反的反应。我们得出的结论是，栖息地开放通过与栖息地变化相关的扩散和适应，在非洲热带谱系的进化史上发挥了重要作用。