[Article] 具有警戒性的箭毒蛙Dendrobates tinctorius的性雙型性與族群內體色變異

圖片來源：本文章

原文標題：Sexual dimorphism and intra-populational colour pattern variation in the aposematic frog Dendrobates tinctorius

摘要 [原文網址]

Despite the predicted purifying role of stabilising selection against variation in warning signals, many aposematic species exhibit high variation in their colour patterns. The maintenance of such variation is not well understood, but it has been suggested to be the result of an interaction between sexual and natural selection. This interaction could also facilitate the evolution of sexual dichromatism. Here we analyse in detail the colour patterns of the poison frog Dendrobates tinctorius and evaluate the possible correlates of the variability in aposematic signals in a natural population. Against the theoretical predictions of aposematism, we found that there is enormous intra-populational variation in colour patterns and that these also differ between the sexes: males have a yellower dorsum and bluer limbs than females. We discuss the possible roles of natural and sexual selection in the maintenance of this sexual dimorphism in coloration and argue that parental care could work synergistically with aposematism to select for yellower males.

先介紹這隻青蛙，這隻D. tinctorius就是市面上所謂的染色箭毒蛙，分布於巴西、法屬圭亞那、蘇利南等地，與有些箭毒蛙一樣具有鮮豔的警戒色，但在不同的族群有不同的體色。

當然，一開始當然要說的是，具有警戒色的物種的多態型是與預測不符合的，因為要有夠強夠集中的衝擊才能讓捕食者知道這是不能吃的，那麼為何這樣的物種還會有多態型或是性雙型性就讓人很好奇了。（相關文章請看Oophaga histrionica與Oophaga pumilio）。

這篇文章看起來算是一個初始調查，調查有幾個型與分佈的關聯性等等，而他們發現族群內的體色變異幅度相當顯著，而且雌雄間也有差異，這群研究者推測這個種之所以可以有多型性，也是因為不管哪個型在光線底下都非常顯眼，也就是都是警戒色，但這部份需要更進一步的實驗才能判斷；另外他們也推測雌蛙在選擇對象時，會優先選擇較黃的雄蛙，因為雄蛙的被捕食率較高，而較黃的雄蛙可能已經避免多次的捕食者攻擊，因此子代較有可能生出同樣類型的體色，會有較高的子代存活率。