肇因於自然或人為活動所引發鹽化，是威脅淡水生態系的重要環境壓力之一，鹽化對於生物多樣性與生態系的影響是近年全球關注的研究議題。兩棲類具有複雜生活史，皮膚通透性高，是研究鹽化對生物影響的理想指標生物。生活史特徵的表現會影響動物的存活與生殖等兩項決定適應度的特徵，因此，藉由研究鹽度對兩棲類生活史特徵表現的影響將有助於我們評估淡水棲地鹽化對兩棲類的影響。兩棲類在個體發生期間所經歷的鹽度變化可能影響其生活史特徵表現而影響其適應度(fitness)。若這種影響是源自動物個體發育階段早期所遭遇的環境壓力而產生，影響是在發育階段後期才表現出來，稱為潛伏效應(latent effects)。目前我們並不清楚蛙類在胚胎時期經歷鹽度壓力是否對其產生潛伏效應。此外，目前關於鹽度對兩棲類影響的研究多針對單因子(鹽度)所產生的影響，較缺乏探討多重因子可能產生的影響。本研究計畫擬以兩年時間去探討鹽化對兩棲類生活史特徵的影響，第一年將探討經歷過鹽度影響的澤蛙(Fejervarya limnocharis)胚胎，在鹽度壓力解除後，是否在個體發生階段後期表現潛伏效應。預期經歷過鹽度壓力的胚胎，之後蝌蚪存活至變態的機會較低、蝌蚪期會延長、且會影響其成長補償而導致較小的變態體型；第二年將探討鹽度與溫度如何影響共域蝌蚪(澤蛙與黑眶蟾蜍)的生活史特徵表現。預期兩種蝌蚪在不同鹽度與溫度的組合條件下會表現競爭上的差異，在多重壓力下，蝌蚪的存活會較低、蝌蚪期會延長，且變態體型會較小，這些發現將有助我我們了解鹽化如何影響兩捿動物之生活史特徵及其適應度。
Increased salinization due to natural or to anthropogenic causes is one of the major stressess threatening freshwater ecosystems, which becomes a global issue and attracts much attention. Amphibians with complex life cycles and high ion permeability of their skin are good indicator species for studying effects of salinization on animals. Life history traits influence animal survival and reproduction, which are two traits determining fitness. Therefore, by explaining how salinity affects life history traits of amphibians will be helpful for assessing effects of salinization on amphibians. Salinity variation experienced by amphibians during ontogeny probably determines their fitness via affecting their life history traits. If effects originate the stress experiences at an early developmental stage in animals but express in later developmental stages after the stresses end, this is called a latent effects. There has been no work identifying if salinity stresses experienced by embryos of frogs have long lasting consequences throughout ontogeny. Additionally, most studies have examined salinity effects on amphibians by a single factor design but very few have examined them by a multi-factors design. I propose a two-year project to evaluate salinization effects on life history traits of amphibians. In the first year, I will study if salinity stresses experienced by embryos of Fejervarya limnocharis have latent effects expressed in later developmental stages. I predict that salinity experienced during embryonic period will result in decreased survival to metamorphosis of tadpoles, delayed time to metamorphosis, and smaller size at metamorphosis due to restricted growth compensation. In the second year, I will study how salinity and temperature influence life history traits of sympatric tadpole species (Fejervarya limnocharis and Duttaphrynus melanostictus). I predict that both tadpole species will express differences on competitive interactions in various combinations of temperature and salinity. The multi-stressor will cause decreased survival to metamorphosis of tadpoles, delayed time to metamorphosis, and decreased size at metamorphosis. Results of this study will shed light on how salinity affects the life history traits and possibly fitness of amphibians.
