THE IMPORTANCE OF FOSSILS IN ELUCIDATING SEED PLANT PHYLOGENY AND MACROEVOLUTION
THE IMPORTANCE OF FOSSILS IN ELUCIDATING SEED PLANT PHYLOGENY AND MACROEVOLUTION
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DOI：
10.1016/0034-6667(87)90040-6
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发表时间：
1987-02-01
影响因子：
1.9
通讯作者：
DONOGHUE, MJ
中科院分区：
文献类型：
--
作者：
DOYLE, JA;DONOGHUE, MJ
为了深入了解有争议的问题，化石的价值，在理解植物发生和宏观进化，我们使用数值简约方法来分析一个数据集积累的活的和化石种子植物的分支研究，不同的修改通过减法和再添加的化石组。一些基于现存群体的进化树与整个数据集的关系是一致的，但种子植物的叶和孢子叶的进化方向以及被子植物和买麻藤属植物的花的进化方向是不明确的。然而，使用石炭纪种子蕨类植物作为外类群有利于这样的概念，即所有种子植物都来自具有蕨类叶的祖先，在松柏目和买麻藤目中有线性二歧叶的双重趋势，并且买麻藤目的花相对于被子植物和Bennettitales的花减少，从整个数据集推断。对于整个数据集，假设针叶蕨类是由类似Callistophyton的扁精子种子蕨演化而来，而不是由类似Archaeopteris的扁精子种子蕨演化而来，这是稍微更简约的，但是如果Archaeopteris是未知的，那么种子蕨假说将受到强烈的支持，而如果Callistophyton是未知的，那么这两种假说都将同样简约。Bennettitales加强买麻藤目和被子植物之间的关系，这只是略强于买麻藤目和针叶类之间的联系时，现存的数据被认为是单独的，而Caytonia澄清被子植物，Bennettitales，买麻藤目和他们的起源从扁精子祖先的生殖同源性。虽然化石信息不会从根本上改变种子植物现存分类群之间的关系，但它可能在其他类群中，它提供了关于事件顺序和可能的适应性因素的独特证据。这两个贡献是特别重要的，当有广泛的同质性和/或当生活群体彼此隔离的大差距，往往是真的更高的类群。
In order to gain insights on the controversial question of the value of fossils in understanding phylogeny and macroevolution, we used numerical parsimony methods to analyze a data set amassed for a cladistic study of living and fossil seed plants, variously modified by subtraction and re-addition of fossil groups. Some cladograms based on extant groups alone are consistent with relationships derived from the whole data set, but the direction of leaf and sporophyll evolution in seed plants and floral evolution in angiosperms and Gnetales is equivocal. However, use of Carboniferous seed ferns as outgroups favors the concept that all seed plants were derived from ancestors with fernlike leaves, that there was a double trend to linear-dichotomous leaves in coniferopsids and Gnetales, and that gnetalian flowers are reduced relative to those of angiosperms and Bennettitales, as inferred from the whole data set. With the whole data set, it is slightly more parsimonious to assume that coniferopsids were derived from Callistophyton-like platyspermic seed ferns than from Archaeopteris-like progymnosperms, but if Archaeopteris were unknown the seed fern hypothesis would be strongly favored, while if Callistophyton were unknown both hypotheses would be equally parsimonious. Bennettitales strengthen relationships between Gnetales and angiosperms, which are only slightly stronger than links between Gnetales and coniferopsids when extant data alone are considered, while Caytonia clarifies reproductive homologies of angiosperms, Bennettitales, and Gnetales and their origin from platyspermic ancestors. Although fossil information does not radically alter inferred relationships among extant taxa in seed plants, it may in other groups, and its provides unique evidence on the sequence of events and possible adaptive factors involved in the origin of groups. Both contributions are especially important when there has been extensive homoplasy and/or when living groups are isolated from each other by large gaps, as is often true of higher taxa.