尖鞘叩頭蟲亞科之系統分類與保育遺傳研究

Abstract

尖鞘叩頭蟲亞科 (Oxynopterinae) 包含了約兩百種種類，是東方區色彩濃厚的一個類群，其成員在叩頭蟲科內是屬於中大型的種類，較具特色代表性的類群如世界最大的叩頭蟲—尖鞘叩頭蟲屬 (Oxynopterus) 以及帶有多變金屬色彩的麗叩頭蟲屬 (Campsosternus)。此兩屬也是叩頭蟲標本買賣市場常見的類群。據過去研究報告記錄顯示超過 10 屬曾歸屬於尖鞘叩頭蟲亞科，然而因種類組成繁雜以及各學者在採樣與特徵選用不一使得高階分類系統不明確。本研究收集了日本、臺灣、中國、越南、泰國、印尼與馬來西亞等地的尖鞘叩頭蟲，總計 5 屬 15 種，以粒線體 DNA COI、16S rDNA、核序列 28S rDNA與內插子 ITS2 等 4 段序列重建其分親緣譜系確立了尖鞘叩頭蟲亞科下屬間之關係 (尖鞘叩頭蟲屬、梳角叩頭蟲屬 (Pectocera)、Sinuaria 以及麗叩頭蟲等 4 屬)，以樹型及物種分佈排除部份過去曾記錄的屬 (Adzusa、Melanactes、Oistus、Semiotus、Semiotinus)，然而這些屬別應歸於何亞科則有待往後研究進一步釐清，即尖鞘叩頭蟲亞科之上更高階的親緣關係需重新檢討。根據上述結果建立尖鞘叩頭蟲亞科 2 族 6 屬的分類系統，包含了 Oxynopterini (尖鞘叩頭蟲族)：Sinuaria、梳角叩頭蟲屬 (Pectocera) 與尖鞘叩頭蟲屬 (Oxynopterus)，以及 Campsosterini (麗叩頭蟲族)：麗叩頭蟲 (Campsosternus)、偉叩頭蟲屬 (Sternocampsus) 和 Rostricephalus 屬。除此之外，S-DIVA (Statistical-Dispersal Vicariance Analysis) 的分析顯示尖鞘叩頭蟲亞科很大的機率起源於中南半島 + 巽他群島地區，往後若加入中國與印度的尖鞘叩頭蟲種類可確認由巽他群島往中南半島的演化方向。PD (Phylogenetic Diversity) 的估算結果顯示尖鞘叩頭蟲亞科在中南半島以及中國東南區塊具有最高的保育優先順序。單一物種的保育則應先確立種級的定義，是否等同於要進行保護的保育單元，方能對族群分佈與估算以及後續保育層級有更精確的評估。經由我們的個案研究可以發現，現行 PD 的應用會受限於樹型採樣的類群，作者認為若以多樣性指標的類群進行監測與採樣，再利用 PD 來篩選生物多樣性熱點區域更能符合目前棲地保育的策略，亦能打破目前台灣保育聚焦在少數物種無法提出大方向方針之困境。

The subfamily Oxynopterinae contains more than 200 species which are mostly from the Oriental regions. All Oxynopterinae are larger sized than other subfamilies. In Oxynopterinae, two genera, Oyxnopterus and Campsosternus are more common than remaining others. Oyxnopterus contains the largest click beetle in the world while the Campsosternus has metallically color with highly diversified pattern beetles. Literarily, more than ten genera of Oxynopterinae have been recorded. Its complex and numerous species composition along with different sampling and characters used by researchers are making the high level classification system unclear. In this study, a total of 15 species (in 5 genera) of Oxynopterinae from Japan, Taiwan, China, Vietnam, Thailand, Indonesia and Malaysia were analyzed. The phylogenetic relations between genera (including Oxynoterus, Pectocera, Sinuaria, Campsosternus) under Oxynopterinae were inferred and confirmed by using mitochondrial DNA COI, 16S rDNA, nuclear 28SrDNA and intron ITS2 sequence fragment. Adzusa, Melanactes, Oistus, Semiotus and Semiotinus were excluded from Oxynopterinae based on tree topology and species distributions. Further investigations required to be accomplished to confirm the subfamily those excluded genera. According to the results, we proposed a systematic classification of Oxynopterinae with 6 genera in 2 tribes in which Oxynopterini includes Sinuaria, Pectocera, and Oxynopterus, and Campsosterini includes Campsosternus, Sternocampsus, and Rostricephalus. Our study from S-DIVA (Statistical-Dispersal Vicariance Analysis) also revealed that Oxynopterinae might be originated from Indo-China + Sunda Islands area. The evolutionary trend from Sunda to Indo-China may be confirmed if additional specimens from China and India could be included. The result of PD (Phylogenetic Diversity) estimation indicated that Indo-China and the Southeast China are the highly protected priority area of Oxynopterinae. For single species protection, the definition of species most be confirmed (whether the protected species is equal to conservation unit). This will have significant impact on the accuracy of future population distributions, population estimate and assessment on protected level. Through our studies, it was found that the current PD application is limited due to the sampling of tree topology. I suggest the monitoring and sampling group should focus on biodiversity indicator which make the result of PD estimate meaningful in selecting biodiversity hotspot area. This method not only matches the policy of habitat conservation in Taiwan but also breaks the plight of efforts too much on single species and cannot give a general direction of conservation policy.