串珠藻目(红藻门)基于形态学证据的系统发育分析

以串珠藻目的16个分类单位加上外类群作为研究对象,选取18个性状作为研究基础,得到18×17的数值矩阵,以分支分类学的方法对串珠藻目的系统发育过程进行分析.采用4种方法进行分支分析,其中以最大同步法的运算结果最为合理,分支图最大步长为269,最小步长为35,实际步长为47,简约系数为0.0513.在串珠藻目中,以红索藻科最为原始,它向两个方向演化,其中一大支随着受精丝的明显膨大,演化出串珠藻科;另一大支则有更多的形态特征发生变化,配子体中出现假薄壁组织,中轴节处产生有定数的分枝,出现发达的外皮层,精子囊以精子囊群的方式成块状或带状出现,果孢子体生于外皮层内部,演化出鱼子菜科和裸管藻科.在串珠藻科中,以串珠藻属的串珠藻组较为原始,而假枝藻属和托氏藻属则较为进化.

Phylogenetic Analysis on the Batrachospermales(Rhodophyta) Based on Morphological Data

The phylogenetic relationship in Batrachospermales was studied by using the principles of cladistic analysis.In the analysis,17 taxa(including outgroup) were selected and 18 informative characters were used.A data matrix consisting of all the extant 17 taxa and 18 characters was analyzed by using Maximal Same Step Length Method,Synthetic Method,Evolutionary Extremal Aggregation Method and Minimal Parallel Evolutionary Method,and the result of Maximal Same Step Length Method is the most logical.In the cladogram the maximal step length was 269,the minimal step length was 35,the actual step length was 47 and the parsimony coefficient was 0.0513.The results suggest that Thoreaceae is the most primitive and evolved along two lines in Batrachospermales,among which one to Batrachospermaceae with trichogyne inflated and the other to Lemaceae and Psilosiphonaceae,their gametophyte with pseudoparenchyma,developed outer cortex,fixed number branches on central axis and spermatangia in patches or rings.In Batrachospermceae,the Section Batrachospermum of the genus Batrachospermum is primitive and the genus Nothocladus and Tuomeya are advanced.