Data from: Correlated evolution of senescence and ephemeral substrate use in the Sordariomycetes

Evolutionary theory predicts that senescence – a decline in reproduction and survival with increasing age - can evolve as a trade-off between the investment in reproduction on one side and in somatic maintenance and repair on the other side. The ecology of a species is crucial here, since it provides the external causes of death that determine the statistical limit to a species’ lifespan. Filamentous fungi are generally believed to be non-senescent, and there are indeed spectacular examples of very old fungal individuals in nature. Yet, for some fungi the growth conditions are ephemeral and therefore senescence is expected to have evolved, like in the coprophilic Podospora anserina, the only well-studied filamentous fungus with intrinsic senescence. Here we hypothesize that rapid senescence is more common in fungi than generally believed and that the phylogenetic distribution of senescence correlates with its ecology. We examined a set of Sordariomycetes for their lifespan and constructed phylogenies based on several nuclear sequences. Part of the strains were from the CBS culture collection, originally isolated from various substrates, some of which ephemeral. In addition we isolated new strains from short-lived substrates. Senescence was observed throughout the phylogeny. Correlation tests support the hypothesis that in the Sordariomycetes senescence is a trait that has arisen as an evolved adaptation to ephemeral substrates, and that it has evolved repeatedly and independently along the phylogeny.

进化理论预测，衰老（senescence）——即随年龄增长繁殖与生存能力衰退——可通过繁殖投入与体细胞维持与修复（somatic maintenance and repair）投入之间的权衡演化而来。物种的生态学特征在此至关重要，因为它提供了决定物种寿命统计上限的外部死亡诱因。丝状真菌（filamentous fungi）通常被认为不会发生衰老，自然界中确实存在极为古老的真菌个体的惊人案例。然而，部分真菌的生存环境较为短暂，因此理论上其会演化出衰老特性，比如嗜粪性的鹅掌囊壳孢（Podospora anserina）——目前唯一被深入研究的具有内在衰老特性的丝状真菌。本研究提出假说：真菌中的快速衰老现象远比此前认知更为普遍，且衰老的系统发育分布与其生态学特征存在关联。我们针对一组粪壳菌纲（Sordariomycetes）物种开展了寿命检测，并基于多个核基因序列构建了系统发育树。部分菌株取自CBS菌种保藏中心（CBS culture collection），其最初分离自多种基质，其中部分基质为临时基质。此外，我们从短生命周期基质中分离得到了新的菌株。研究在整个系统发育分支中均观察到了衰老现象。相关性检验验证了本研究的假说：在粪壳菌纲中，衰老是一种因适应临时基质而演化而来的性状，且该性状在系统发育过程中多次独立演化出现。