Crawford Monique, Jesson Linley K, Garnock-Jones Phil J
Victoria University of Wellington, School of Biological Sciences, P.O. Box 600, Wellington 6140, New Zealand.
Evolution. 2009 May;63(5):1129-42. doi: 10.1111/j.1558-5646.2009.00615.x. Epub 2008 Jan 14.
In mosses, separate and combined sexes are evolutionarily labile, yet factors selecting for this variation are unknown. In this study, we investigate phylogenetic correlations between sexual system and five life-history traits (asexual reproduction, chromosome number, gametophore length, spore size, and seta length). We assigned states to species on a large-scale phylogeny of mosses and used maximum likelihood analyses to test for the correlations and investigate the sequence of trait acquisition. Mosses in lineages with separate sexes were significantly more likely to be large, whereas those in lineages with combined sexes had higher chromosome numbers. Moreover, evolutionary transitions to separate sexes were more likely to occur in lineages with small spores. There was no support for a correlation between asexual reproduction and separate sexes. These results suggest that sexual system evolution is influenced by traits affecting mate availability and the dispersal of gametes and spores, and provides evidence for the existence of syndromes of life-history traits in mosses.
在苔藓植物中，雌雄异体和雌雄同体在进化上是不稳定的，但选择这种变异的因素尚不清楚。在本研究中，我们调查了性系统与五个生活史特征（无性繁殖、染色体数目、配子体长度、孢子大小和蒴柄长度）之间的系统发育相关性。我们在苔藓植物的大规模系统发育树上为物种指定状态，并使用最大似然分析来测试相关性并研究性状获得的顺序。雌雄异体谱系中的苔藓植物更有可能体型较大，而雌雄同体谱系中的苔藓植物染色体数目更高。此外，向雌雄异体的进化转变更有可能发生在孢子较小的谱系中。没有证据支持无性繁殖与雌雄异体之间存在相关性。这些结果表明，性系统进化受影响配偶可得性以及配子和孢子扩散的性状影响，并为苔藓植物生活史性状综合征的存在提供了证据。
