文獻來源: Yoder, J.B., Smith, C.I. & Pellmyr, O. 2010. How to become a yucca moth: minimal trait evolution needed to establish the obligate pollination mutualism. Biological Journal of the Linnean Society 100: 847–855. With 2 figures
簡介
簡介
專一傳粉者與植物，經典的例子如絲蘭與絲蘭蛾（絲蘭僅依靠絲蘭蛾傳粉，而絲蘭蛾幼蟲只取食絲蘭之種子），兩者之間互利共生的起源似乎需要大量的特徵演化與特化。為了瞭解實際參與建立互利共生關係、而不是在適應前就已經產生的特徵所佔程度之多寡，作者利用延伸的親緣關係評估與對深度分化類群以改進過的方式取樣，以首次重建傳粉的絲蘭蛾和它們不傳粉的親戚之間的特徵演化。作者的研究結果顯示，許多絲蘭蛾的重要生活史特徵，諸如：幼蟲於植物的胚珠內取食、成蟲具有具切割功能的特殊產卵管以及在乾燥環境中的單子葉木本植物上拓殖等特徵，可能在絲蘭蛾專一性互利共生的特徵出現之前就已經存在。有了這些先存特徵，互利共生特性的絲蘭蛾的新特徵即不外乎活躍的傳粉行為和可促進花粉收集和儲存之觸手狀附屬物。上述結果暗示高度專一性的互利共生現象是奠基於早期絲蘭蛾科和其寄主植物的先存交互作用基礎之上，再透過微小的特徵演化而產生。
由圖中(原文Figure 2.)可看出絲蘭蛾之祖先類群為廣食性，食草範圍包括單子葉和雙子葉植物，取食部位包括有花、胚珠、莖與葉片等，而後其遠親分化為以雙子葉植物為食，絲蘭蛾科與其近緣類群由取食薔薇科的成員演化至以木本單子葉植物為寄主植物：絲蘭蛾科朝以龍舌蘭科為食、取食胚珠部位的方向演化，其近緣類群假絲蘭蛾屬(Prodoxus)的物種以絲蘭和龍舌蘭的莖和果實為食。
由圖中(原文Figure 2.)可看出絲蘭蛾之祖先類群為廣食性，食草範圍包括單子葉和雙子葉植物，取食部位包括有花、胚珠、莖與葉片等，而後其遠親分化為以雙子葉植物為食，絲蘭蛾科與其近緣類群由取食薔薇科的成員演化至以木本單子葉植物為寄主植物：絲蘭蛾科朝以龍舌蘭科為食、取食胚珠部位的方向演化，其近緣類群假絲蘭蛾屬(Prodoxus)的物種以絲蘭和龍舌蘭的莖和果實為食。Abstract
The origins of obligate pollination mutualisms, such as the classic yucca–yucca moth association, appear to requireextensive trait evolution and specialization. To understand the extent to which traits truly evolved as part of establishing the mutualistic relationship, rather than being pre-adaptations, we used an expanded phylogenetic estimate with improved sampling of deeply-diverged groups to perform the first formal reconstruction of trait evolution in pollinating yucca moths and their nonpollinating relatives. Our analysis demonstrates that key life-history traits of yucca moths, including larval feeding in the floral ovary and the associated specialized cutting ovipositor, as well as colonization of woody monocots in xeric habitats, may have been established before the obligate mutualism with yuccas. Given these pre-existing traits, novel traits in the mutualist moths are limited to the active pollination behaviours and the tentacular appendages that facilitate pollen collection and deposition. These results suggest that a highly specialized obligate mutualism was built on the foundation of pre-existing interactions between early Prodoxidae and their host plants, and arose with minimal trait evolution.
The origins of obligate pollination mutualisms, such as the classic yucca–yucca moth association, appear to requireextensive trait evolution and specialization. To understand the extent to which traits truly evolved as part of establishing the mutualistic relationship, rather than being pre-adaptations, we used an expanded phylogenetic estimate with improved sampling of deeply-diverged groups to perform the first formal reconstruction of trait evolution in pollinating yucca moths and their nonpollinating relatives. Our analysis demonstrates that key life-history traits of yucca moths, including larval feeding in the floral ovary and the associated specialized cutting ovipositor, as well as colonization of woody monocots in xeric habitats, may have been established before the obligate mutualism with yuccas. Given these pre-existing traits, novel traits in the mutualist moths are limited to the active pollination behaviours and the tentacular appendages that facilitate pollen collection and deposition. These results suggest that a highly specialized obligate mutualism was built on the foundation of pre-existing interactions between early Prodoxidae and their host plants, and arose with minimal trait evolution.
