杉科的两条演化路线

 本文根据核型资料提出杉科可能存在A、L两条演化路线，前者包括由原始到进化的柳杉属、水松属、落羽杉属、台湾杉属，以平均臂比快速增加、染色体长度比缓慢增加为特征；后者包括依序进化的水杉属、巨杉属、红杉属、杉木属(可能还有密叶杉属)，以平均臂比缓慢增加、染色体长度比迅速增加为特点。该结论也得到形态学、解剖学、胚胎学等资料的支持。

Two Evolutionary Lines of Taxodiaceae

According to the karyotypic  data the present author proposes two evolutio-nary lines, A and L (Fig. 1), in Taxodiaceae (Exclud. Sciadopitys). The former is characteri-zed by a relatively rapid increase of the mean arm ratio but a relatively slow rise of the ratio ofthe longest chromosome to the shortest one and it is composed of  Cryptomeria, Glyptostrobus,Taxodium and Taiwania, which advance from primitive to progressive in the order. The latteris characterized by, on the contrary, a relatively slow increase of mean arm ratio and a relative-ly rapid rise of the ratio of chromosome size and it comprises   Metasequoia, Sequoiadendron,Sequoia and Cunninghamia (probably Athrotaxis also), which advance in the order. The infer-ence is supported by the data from morphology, anatomy, embryology and so on.Key words  Taxodiaceae; Karyotype; Evolutionary line