蕨类植物不同孢子裂缝类型在中国的分布格局

孢子在蕨类植物分类及有性生殖过程中具有重要地位, 一般都具有裂缝构造, 常见的是单裂缝和三裂缝, 极少数情况下有多裂缝的变异类型。我们统计了中国蕨类2,281种(含种下单位)的孢子裂缝类型, 来探讨两种不同裂缝类型的分布格局。结果表明: (1)具有单裂缝类型的物种数多于三裂缝类型, 单裂缝与三裂缝物种数目的比值(单/三比)与纬度和海拔呈正相关。随着温度下降以及降水量的降低, 具单裂缝孢子的物种比例增加。推测具单裂缝孢子的蕨类分布范围更广, 更适宜生活在干旱及高纬度或高海拔寒冷地区, 而具三裂缝孢子的蕨类更适宜存在于低纬度或低海拔的温暖地区; (2)蕨类植物孢子裂缝类型不是单次起源, 可能存在平行演化。本研究可以为蕨类植物的起源演化与生态适应等研究提供一定的证据。

Distributional patterns of the monolete and trilete ferns in China

Spores are important for fern classification and sexual reproduction and they usually have apertures; monolete (bilateral) and trilete (tetrahedral) are the two common types. All of the 2,281 native Chinese fern species (including subspecies and varieties) were included in our survey of monolete and trilete species ratios and their distribution patterns. Result revealed that (1) the number of monolete species was higher than the number of trilete, and there was a positive correlation between the ratio of monolete: trilete species (MTR) and latitude, and also between MTR and altitude. MTR was also shown to increase with decreases in temperature and rainfall. Monolete ferns were found to have larger distributional areas than trilete ones and to be more tolerant to a colder and drier climate. It is hypothesized that monolete ferns have a strong capacity to adapt to an extreme habitat; and that (2) neither monolete nor trilete spore are of single origin as parallel evolution might exist during the evolution of ferns. This study sheds new light on niche adaptation in ferns, as well as the evolution and diversification of ferns.