Department of Geological Sciences, Stanford University, 450 Jane Stanford Way, Building 320, Room 118, Stanford, CA 94305, USA.
School of Environment, Earth and Ecosystem Sciences, Open University, Walton Hall, Milton Keynes MK7 6AA, UK.
Proc Biol Sci. 2023 Nov 8;290(2010):20231810. doi: 10.1098/rspb.2023.1810. Epub 2023 Nov 1.
Vascular plant reproductive structures have undoubtedly become more complex through time, evolving highly differentiated parts that interact in specialized ways. But quantifying these patterns at broad scales is challenging because lineages produce disparate reproductive structures that are often difficult to compare and homologize. We develop a novel approach for analysing interactions within reproductive structures using networks, treating component parts as nodes and a suite of physical and functional interactions among parts as edges. We apply this approach to the plant fossil record, showing that interactions have generally increased through time and that the concentration of these interactions has shifted towards differentiated surrounding organs, resulting in more compact, functionally integrated structures. These processes are widespread across plant lineages, but their extent and timing vary with reproductive biology; in particular, seed-producing structures show them more strongly than spore or pollen-producing structures. Our results demonstrate that major reproductive innovations like the origin of seeds and angiospermy were associated with increased integration through greater interactions among parts. But they also reveal that for certain groups, particularly Mesozoic gymnosperms, millions of years elapsed between the origin of reproductive innovations and increased interactions among parts within their reproductive structures.
植物的生殖结构无疑在进化过程中变得更加复杂，演化出了高度分化的部分，以专门的方式相互作用。但是，在广泛的范围内量化这些模式是具有挑战性的，因为谱系产生了不同的生殖结构，这些结构往往难以比较和同源化。我们开发了一种新的方法，通过网络来分析生殖结构内部的相互作用，将组成部分视为节点，将部分之间的一系列物理和功能相互作用视为边缘。我们将这种方法应用于植物化石记录，表明相互作用总体上随着时间的推移而增加，并且这些相互作用的集中程度向分化的周围器官转移，导致结构更加紧凑、功能更加集成。这些过程在植物谱系中广泛存在，但它们的程度和时间随生殖生物学而变化；特别是，产生种子的结构比产生孢子或花粉的结构表现出更强的作用。我们的研究结果表明，主要的生殖创新，如种子的起源和被子植物的出现，与部分之间相互作用的增加有关，从而导致了更大的整合。但它们也表明，对于某些群体，特别是中生代的裸子植物，生殖创新的起源与生殖结构中部分之间相互作用的增加之间存在着数百万年的时间差。
