帶魚(Trichiurus spp.)之形態及基因變異

Abstract

帶魚是一類高經濟價值的底棲性魚類，其中又以白帶魚(Trichiurus lepturus)最為重要。 白帶魚在全球三大洋都有分布，產量大多集中在西北太平洋陸棚地區，佔全球總產量80%以上。 先前的研究認為，在西北太平洋陸棚地區的帶魚屬魚類只有白帶魚一個物種，但近年研究指出，在此區域可能有三種帶魚屬魚類。 台灣附近水域先前研究亦指出僅有一種帶魚屬魚類，但在外表上卻有兩型。 本論文利用傳統形態形質特徵、幾何形態測量特徵及粒線體DNA分子特徵來探討帶魚屬的種間及種內之關係。 由形態資料分析發現，所採樣的帶魚屬魚類可以區分出三個有效物種： Trichiurus lepturus Linnaeus, 1758 (白帶魚)，T. nanhaiensis Wang and Xu et al., 1992 (南海帶魚)和T. brevis Wang and You et al., 1992 (短帶魚) 。利用幾何形態測量特徵分析發現，三者在外廓上有明顯差異，並可由眼徑、體高、全長、背鰭起始點到鰓蓋骨後緣長度、上顎先端到背鰭起始點長度等利用判別函數加以區分。 三者在粒線體DNA的Cyt b基因序列分析上，可以明顯區分出來，其結果與形態資料一致。 三種帶魚間其DNA兩兩間差異均大於10%，且沒有鑲嵌現象。 本研究結果顯示，在西北太平洋水域的帶魚屬魚類，應有三物種: Trichiurus lepturus Linnaeus, 1758 (白帶魚)，T. nanhaiensis Wang and Xu et al., 1992 (南海帶魚)和T. brevis Wang and You et al., 1992 (短帶魚)。 本報告並重新整理這些物種命名的問題。

The cutlassfish (Trichiurus spp.) is a group of ribbon-like demersal fishes inhabited in continental shelf with high commercial value in the world. The most important species is the cosmopolitan one, Trichiurus lepturus, which distribute across tropical and subtropical waters worldwide. Most of the commercial catches of cutlassfish come from the shelf regions of northwest Pacific, in which area the landings accounted to 80% of the world catches. Previous studies indicate that, one species of the Trichiurus occurred in the regions of northwest Pacific. In recent studies, three species have been added to taxonomic and faunal lists in the region. In the waters around Taiwan, there were 2 phenotypes can be identified similar to T. lepturus, however it is contentious that 2 phena or 2 species should be estimated from morphological and biogeographic analysis. In this study, I apply quantitative methods to analyze morphological characters and molecular markers dually, and expect to solve those taxonomic problems and to clarify the nomenclature status of Trichiurus. The results showed that there are three valid species identified in our samples collected from the vicinity waters around Taiwan; T. lepturus, T. nanhaiensis and T. brevis. Trichiurus brevis is the most distinctive among the three species by having less than 35 dorsal fin elements, and the separation of T. nanhaiensis from T. lepturus is based on fusion or not of forntal bone. Principal component and discrimination function analysis confirmed previous finding with statistical significance (<0.3% mis-identification). Partitioning of molecular variance indicated that more than 10% of variations were ascribed to inter-specific, and the specific taxonomic status is firmly supported.