小族群台北赤蛙(Rana taipehehsis)的族群動態與年齡結構之探討

The investigation on population dynamics and demography in two small populations of Taipei grass frog (Rana taipehensis)

連志台(Lien Chih-Tai)

指導教授 ： 呂光洋

國立臺灣師範大學/理學院/生命科學研究所/碩士(2004年)

摘要

無資料

關鍵字

台北赤蛙 ； 族群動態 ； 年齡結構 ； HASH(0x9121298)

並列摘要

Abstract
Taipei grass frog (Rana taipehensis van Denburgh, 1909) is a small to median size frog. In Taiwan, the distribution of Taipei grass frog is fragmented in Sanchih, Yangmei, Kuantien, and Neipu. The population size of each study site is very small. From 2003 to 2004, we investigated the population dynamics of Taipei grass frog in Sanchih and Yangmei. After obtaining frog’s age with skeletochronology, we constructed the population age structures of each population.
The sex ratio of reproductive populations in Sanchih and Yangmei both are skewed to males. The ratio for male to female frogs from Sanchih (16.13：1) is almost as twice as the one in Yangmei (6.97：1). Estimated population size with Schnabel method in Sanchih, we got 347 frogs in 2003, and 203 in 2004. Yangmei population was 544 in 2003 and 226 in 2004. In Yangmei, the survival probability changed with time and males have higher survival probability. The encounter probability changed with cumulative precipitation before each surveys and males also have higher encounter probability.
Both in males and females, the oldest frog is 4 years old with skeletochronology. The age of female frog (2.58 ± 0.09LAGs) is significantly older than male (2.30 ± 0.03LAGs). Based on the age structure, males reached to sexual mature and join to the breeding population within 1 year while females in 2 years. The survival rates between age 2 to 3 in Sanchih are: male - 0.33, female - 0.22. The survival rates between age 3 to 4 are: male - 0.02, female - 0. In Yangmei, survival rates are male - 0.23, female - 0.68 between age 2 - 3 and male -0.06, female - 0.12 between age 3 - 4. With Multiple Linear Regression analysis, the result indicated that SVL is significantly different by age, sex, year, and place.
With VORTEX, we simulated the extinction probability of Yangmei population in the 100th year starting from now is 0, when the offspring of a female reproduced is 34.

While in Sanchih will extinct in the 26th year. By doubling the female percentage, the population in Sanchih will have 64% survival probability in the 100th year starting from now. This indicates that sex ratio plays a major role in the persistence of Taipei grass frog. Mean offspring of a female reproduced may also have serious effect, when it dropped sharply.

並列關鍵字

Rana taipehensis ； population dynamics ； demography ； VORTEX