凹耳臭蛙胚胎发育及其分类学意义(英文)

通过人工受精的方法获得的凹耳臭蛙(Odorrana tormota)的早期胚胎及胚后幼体的发育过程,根据胚胎发育过程中的形态及生理特征变化规律进行分期。把凹耳臭蛙的发育过程分成两个阶段:1)早期胚胎发育阶段,即从蛙卵受精到鳃盖完成期,在18～23℃水温下,凹耳臭蛙早期胚胎发育阶段历时324h;2)蝌蚪发育阶段,即从鳃盖完成期结束到尾部被完全吸收,本阶段在20～24℃水温条件下历时1207h。凹耳臭蛙蝌蚪未发现腹吸盘特征,从形态特征上支持了分子系统分类学将之从湍蛙属划出的观点。实验中发现,多数胚胎在8细胞期为纬裂,16细胞期为经裂,同时有小部分胚胎(1.5%)在8细胞期为经裂,16细胞期为纬裂。该文进一步讨论了影响卵裂率、孵化率、发育速度,以及生态适应的因素。

Embryonic development of the concave-eared torrent frog with its significance on taxonomy

We investigated the early embryonic and larval development of the concave-eared torrent frogs,Odorrana tormota (Amphibia,Anura,Ranidae).Embryos were derived from artificial fertilization of frogs' eggs,and the staging of development was based on morphological and physiological characteristics.Two major periods of development were designated:i) early embryonic period,from fertilization to operculum completion stage,lasted for 324 h at water temperature (WT) 18-23℃;ii) larval period,from operculum completion stage to tail absorbed stage,took 1207 h at WT 20-24℃.Tadpoles of the concave-eared torrent frogs showed no evidence of abdominal sucker.Absence of this key characteristic supports the view from molecular systematics that concave-eared torrent frog does not belong to the genus Amolops.Two cleavage patterns were observed in embryos at 8-cell and 16-cell stages,with Pattern 1-2 (latitudinal cleavage at the 8-cell stage,and meridional cleavage at the 16-cell stage with two perpendicular meridional furrows) being the predominant pattern and only 1.5% belonging to Pattern Ⅱ (meridional cleavage at the 8-cell stage and latitudinal cleavage at the 16-cell stage).The factors affecting cleavage and hatching ratios,developmental speed,and ecological adaptation were discussed.