台灣地區溫泉水域及冷水溪流日本樹蛙(Buergeria japonica)生殖族群體型差異及生長之探討

Abstract

日本樹蛙(Buergeria japonica)是台灣29種原生蛙類中唯一會選擇在溫泉水域及冷水溪流進行繁殖活動的蛙類。本研究探討台灣地區溫泉水域與冷水溪流日本樹蛙生殖族群的體型、年齡及成長是否受環境影響而有差異。研究結果發現日本樹蛙有明顯雌雄二型性，雌蛙體型較大；雄蛙2歲達到性成熟、雌蛙於3歲達到性成熟，透過觀察趾骨切片推論造成雌蛙體型較大的原因與雌蛙延後性成熟有關。運用von Bertalanffy growth model估算台灣地區日本樹蛙之成長模式，結果顯示日本樹蛙雄蛙成長係數(K)為0.51，吻肛長理論極限值為29.96 mm；雌蛙成長係數為0.23，吻肛長理論極限為44.96 mm。 溫泉水域日本樹蛙生殖族群，雄蛙平均吻肛長26.35±1.46 mm，估計年齡由2至5歲，平均估計年齡3.53±0.68 (n=184)歲，雌蛙吻肛長31.51±2.38 mm，估計年齡由3至5歲，平均估計年齡4.29±0.60(n=42)。冷水溪流日本樹蛙生殖族群，雄蛙平均吻肛長27.33±1.16 mm，估計年齡由3至5歲，平均估計年齡4.02±0.70(n=197)歲，雌蛙平均吻肛長34.06±2.20 mm，估計年齡由4至6歲，平均估計年齡4.69±0.54(n=29)。研究結果顯示，冷水溪流日本樹蛙生殖族群平均年齡及 體型均顯著高於溫泉水域，可能與溫泉水域日本樹蛙提早投入生殖有關。 趾骨切片方面，冷水溪流生殖族群趾骨周長及各LAG周長大於溫泉水域生殖族群，各年趾骨成長量在兩水域生殖族群間沒有差異。溫泉水域雄蛙生殖族群的骨髓空腔佔趾骨百分比高於冷水溪流雄蛙族，推測是因為溫泉高溫使日本樹蛙代謝加速所造成。Japanese Buerger's frog (Buergeria japonica) is the only species breeding in hot spring and aquatic environment in Taiwan. This study discussed the differences of the body size, age and growth of breeding population in Japanese Buerger's frog between hot spring and aquatic environment. The results showed the sexual dimorphism in this species. Males reached sexual maturity at 2 years old, and female did at 3 years old. Growth was estimated according to von Bertalanffy model. The growth coefficient (K) was 0.51 in males and 0.23 in females. In hot spring, the mean snout-vent length of the breeding population was 26.35±1.46 mm and 31.51±2.38 mm, age range from 2 to 5 years old (mean = 3.53±0.68) and 3 to 5 years old (mean = 4.29±0.60) in males and females, respectively. In natural aquatic environment, the mean snout-vent length was 27.33±1.16 mm and 34.06±2.20 mm, age range from 3 to 5 years (mean = 4.02±0.70) and 4 to 6 years (mean = 4.69±0.54) in males and females. The difference of body size and age between hot spring and aquatic environment was significant. According to the skeletochronology performed on the phalanges, the average of phalanges circumference and circumference of each LAGs of aquatic environment breeding population were greater than hot spring breeding population, the marrow cavity percent of section of hot spring population was significantiy higher, but the growth in amount of phalange circumference per year in both population were similar.