Brachyspira asperella Yu et Zhang的个体发育

ONTOGENY OF BRACHYSPIRA ASPERELLA YU ET ZHANG

对Brachyspira asperella Yu et Zhang的40个个体的测量统计表明,此种在生长发育过程中可以区分出3个生长阶段:幼年期壳体生长速度缓慢,壳形卵圆形,胎壳乳突状,壳口圆形;成年期生长迅速,壳高显著大于壳宽的增长率,壳形卵圆形-长卵圆形,壳口卵圆形;老年期生长速度缓慢,壳形长卵圆形,壳饰强烈。这3个生长期代表了此种的个体发育过程。研究化石腹足类种的个体发育过程不仅能了解这一类群的系统发生史、生物演化过程及生物间的亲缘关系,而且能提高物种研究程度,避免分类上的错误。

According to individual size, embryonic shape, number of growth lines and spire of Brachyspira asperalla Yu et Zhang, three growth stages can be distinguished from 40 specimens, namely, young stage, mature stage and old stage. The shell might grow slowly and gradually, but the growth rate of the young and mature stages was much greater than that of the old stage. The shell in early stage was quite different in shape from the later one, but the shape of embryo and the surface ornamentation were similar. Furthermore, their growth patterns were also very similar as compared with the living Succinea. Ontogeny is very important in the study of process of phylogeny, and very helpful for us to know the phylogenetic history and evolution of organisms, and, especially, to avoid misidentification of species.