池塘中斑索蟾的种群结构、个体生长与存活率

在澳大利亚新南威尔士南部沿海,作者搜集了一个池塘繁殖的斑索蟾(Crinia signifera)的种群统计资料。通过捕捉进出池塘的1 612只个体,获得种群大小、结构、生长率、性成熟时的大小和年龄、死亡率及寿命资料。迁移高峰从6月持续到11月,蛙的最高、最低遇见数量分别出现在春季和秋季。但第2年,该池塘蛙的数量明显减少,可能是由于补充到种群中的幼体数量很少的缘故。6个月后个体的重捕率很低;但距第一次捕获18个月以后,仍有个别个体再次被捕获。性成熟时,雌性比雄性的身体大一些。生长曲线显示,雌性比雄性的生长更快,所以更早地达到性成熟。研究种群的数量、结构和死亡率趋势等与已知的其它Crinia signifera种群基本一致。但研究种群迁移活动的高峰出现较晚,并且夏季的活动水平明显很高。这种长的活动时间可能会导致存活率的下降,同时有利于选择迅速性成熟的雌性动物学报51 (3) : 393 -400 , 2005]。

Population structure, individual growth and survival of an Australian frog Crinia signifera at a pond

I studied a population of the common eastern froglet Crinia signifera breeding at a pond in southern coastal New South Wales. I captured frogs entering and leaving the pond to characterise population size and structure, growth rates, size and age at sexual maturity, mortality rates and longevity. The population was large (1 612 individuals) with peak migration occurring from June to November. Highest numbers of frogs were present in spring and lowest in autumn. I captured fewer frogs in the second year, possibly resulting in declines in relative levels of juvenile recruitment. Few individuals were recaptured more than six months after first capture, but some frogs were recaptured after 18 months. Females appeared to reach sexual maturity at a slightly larger size than males. Growth curves indicated that females grew faster than males and so could potentially achieve sexual maturity more rapidly than males. Population size and structure, and trends in mortality are similar to those found in other studies of this species. However, peak migratory activity occurred later in the year and activity levels in summer are much greater than found in other studies. A long annual activity period may result in reduced survival rates and select for rapidly maturing females.