Department of the Geophysical Sciences, University of Chicago, 5734 South Ellis Avenue, Chicago, IL 60637, USA.
Proc Biol Sci. 2011 Oct 7;278(1720):3003-8. doi: 10.1098/rspb.2010.2648. Epub 2011 Feb 23.
Conifers are an excellent group in which to explore how changing ecological interactions may have influenced the allocation of reproductive tissues in seed plants over long time scales, because of their extensive fossil record and their important role in terrestrial ecosystems since the Palaeozoic. Measurements of individual conifer pollen-producing and seed-producing cones from the Pennsylvanian to the Recent show that the relative amount of tissue invested in pollen cones has remained constant through time, while seed cones show a sharp increase in proportional tissue investment in the Jurassic that has continued to intensify to the present day. Since seed size in conifers has remained similar through time, this increase reflects greater investment in protective cone tissues such as robust, tightly packed scales. This shift in morphology and tissue allocation is broadly concurrent with the appearance of new vertebrate groups capable of browsing in tree canopies, as well as a diversification of insect-feeding strategies, suggesting that an important change in plant-animal interactions occurred over the Mesozoic that favoured an increase in seed cone protective tissues.
松柏类植物是一个很好的研究对象，可以用来探索随着时间的推移，生态相互作用的变化如何影响种子植物生殖组织的分配，因为它们有广泛的化石记录，并且自古生代以来就在陆地生态系统中发挥了重要作用。对从古生代到现代的个体松柏类植物花粉产生和种子产生的球果的测量表明，花粉球果的组织投入相对量保持不变，而种子球果在侏罗纪的比例组织投入则急剧增加，并持续到今天。由于松柏类植物的种子大小在整个时间范围内保持相似，因此这种增加反映了对保护性球果组织的更大投资，例如坚固、紧密排列的鳞片。这种形态和组织分配的转变与能够在树冠中觅食的新型脊椎动物群的出现以及昆虫取食策略的多样化广泛同时发生，表明中生代植物-动物相互作用发生了重要变化，有利于增加种子球果的保护组织。
