Premise of research. Serotiny is a specialized dispersal mechanism in which seeds are retained on the parent plant and released following a disturbance event. This strategy has evolved repeatedly in plants inhabiting fire-prone regions and typically requires adaptations for the protection and release of seeds. We explore the relationship between serotiny and reproductive morphology in the Cupressaceae conifer clade, asking whether serotiny is associated with the evolution of larger, more protective seed cones. Methodology. We compiled cone volume data from 72 extant Cupressaceae species, with detailed cone and seed mass measurements from 19. Using phylogenetic regressions and a previously published phylogeny, we reconstructed how many times serotiny evolved in Cupressaceae and asked whether its appearance was correlated with larger seed cones. We also tested whether cones from serotinous taxa produced proportionally more sterile tissues than those from nonserotinous taxa. Pivotal results. Serotiny has likely evolved five times within extant Cupressaceae, and each time it is correlated with the evolution of larger seed cones. The larger cones of serotinous taxa do not show proportionally more investment in sterile tissues, however. Conclusions. The relationship between cone size and serotiny is particularly strong in Cupressaceae because their branching architecture favors the production of small cones; fire regimes can then exert a strong selective pressure favoring larger ones. Conifers that produce generally larger seed cones may be less likely to show a correlation with serotiny. Considering seed cone size and branching architecture together, however, may allow for the interpretation of serotiny in the conifer fossil record.

中文翻译：

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柏科针叶树血清素和种锥大小的演变

研究的前提。血清素是一种特殊的传播机制，其中种子保留在亲本植物上并在干扰事件后释放。这种策略在栖息于火灾易发地区的植物中反复演变，通常需要对种子的保护和释放进行调整。我们探索了柏科针叶树进化枝中血清素和生殖形态之间的关系，询问血清素是否与更大、更具保护性的种子球果的进化有关。方法。我们收集了来自 72 个现存柏科物种的锥体体积数据，以及来自 19 个物种的详细锥体和种子质量测量。使用系统发育回归和先前发表的系统发育，我们重建了柏科中血清素进化的次数，并询问其外观是否与较大的种子锥相关. 我们还测试了来自血清类群的锥体是否比来自非血清类群的锥体产生了更多的无菌组织。关键结果。血清素可能在现存柏科中进化了五次，每次都与更大的锥体的进化有关。然而，较大的血清类群锥体并未按比例显示对无菌组织的更多投资。结论。锥体大小和血清素之间的关系在柏科中尤为强烈，因为它们的分枝结构有利于产生小锥体；然后，火势可以施加强大的选择压力，有利于较大的火势。产生通常较大的种球果的针叶树可能不太可能显示与血清素的相关性。然而，同时考虑种子锥大小和分枝结构，