MORPHOLOGICAL VARIATION AND AGE-CLASS DETERMINATION IN OVERWINTERING TADPOLES OF THE TAILED FROG, ASCAPHUS-TRUEI
MORPHOLOGICAL VARIATION AND AGE-CLASS DETERMINATION IN OVERWINTERING TADPOLES OF THE TAILED FROG, ASCAPHUS-TRUEI
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DOI：
10.1111/j.1469-7998.1990.tb04301.x
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发表时间：
1990-02-01
影响因子：
2
通讯作者：
BROWN, HA
中科院分区：
文献类型：
--
作者：
BROWN, HA
描述了北喀斯喀特山亚高山种群不同年龄组Ascaphus蝌蚪的形态变化和发育。成年雌性在7月中旬产卵，胚胎在8月下旬发育成孵化蝌蚪。适应激流的蝌蚪在寒冷的沃茨中发育，在冰雪覆盖的溪流中过冬，四年内完成蜕变。在9月/10月，可能有五个年龄组的蝌蚪：队列0，孵化蝌蚪（总长度（ToL）= 11毫米）;队列1，一年的蝌蚪（ToL = 32毫米）;队列2，两年的蝌蚪（ToL = 36毫米）;队列3，三年的蝌蚪（ToL = 42毫米）;和队列4，变态蝌蚪或最近转化的青蛙（ToL = 20毫米）。这些年龄组的确定是基于总长度，体重和后肢和前肢的分化。肢芽在蝌蚪发育的第一年出现，但前肢被体壁和鳃腔所隐藏，后肢被肛褶所隐藏。根据总的大小频率和形态分化的数据和文献回顾，山地种群的幼虫生命期不是通常接受的两三年，而是大约四年。
The morphological variation and development of different age classes of Ascaphus tadpoles is described for a subalpine population in the North Cascade Mountains. Adult females lay eggs in mid July, the embryos develop into hatching tadpoles in late August. The torrent-adapted tadpoles develop in cold waters, overwintere in ice-covered streams and complete metamorphosis in four years. In September/October there may be five age-classes of tadpoles: cohort 0, hatchling tadpoles (total length (ToL) = 11 mm); cohort 1, one-year tadpoles (ToL = 32 mm); cohort 2, two-year tadpoles (ToL = 36 mm); cohort 3, three-year tadpoles (ToL = 42 mm); and cohort 4, metamorphosing tadpoles or recently transformed frogs (ToL = 20 mm). Determination of these age-classes is based upon total length, body weight and hind limb and forelimb differentiation. The limb buds appear in the first year of the tadpole development, but the forelimbs are hidden by the body wall and branchial chamber, and the hind limbs are concealed by the anal fold. Arguments are presented from the data of total size-frequency and morphological differentiation and a review of the literature that the larval life period in montane populations is not two or three years, as is commonly accepted, but is approximately four years.