以分子證據探討台灣及鄰近島嶼蜑螺科之分類

Taxonomy of the Neritidae in Taiwan and its adjacent islands based on molecular evidence

林怡如(Yi-Ru Lin)

指導教授 ： 邱郁文

高雄醫學大學/生命科學院/生物醫學暨環境生物學研究所/碩士(2012年)

https://doi.org/10.6832/KMU.2012.00122

摘要

台灣及鄰近島嶼的蜑螺科物種有五屬，分別為蜑螺屬（Nerita Linnaeus, 1758）、水彩蜑螺屬（Smaragdia Issel, 1869）、石蜑螺屬（Clithon Montfort, 1810）、河蜑螺屬（Neritina Lamarck, 1816）與壁蜑螺屬（Septaria Ferussac, 1807）。過去蜑螺科貝類主要以形質特徵（殼、口蓋與動物的內部構造）做為分類依據，然而蜑螺的形態變異極大，此高度形態變異造成單以外部形質特徵進行分類的困難，故在分類鑑定上常存有疑慮。因此本研究以台灣及鄰近島嶼的蜑螺為材料，初期整理文獻將形態有所疑慮的物種合併為一形態複合群以方便探討，再進行分子序列分析，本研究利用粒線體上的COI及16S片段建構物種的遺傳資料，以檢測蜑螺殼的外部形態是否與遺傳標誌的分群一致。各屬結果如下：（1）蜑螺屬16個物種各呈一單系群，支持殼的外部形態分類的結果；（2）水彩蜑螺屬3個物種各呈一單系群，支持殼的外部形態分類的結果，台灣地區原紀錄2種，而本研究於東沙島採集發現一可能為新種之個體；（3）石蜑螺屬3個物種各呈一單系群，支持殼的外部形態分類的結果，其他1組形態複合群並不呈一單系群，且不支持殼的外部形態分類的結果；（4）河蜑螺屬4個物種與一組形態複合群（Neritina complex 3）各呈一單系群，支持殼的外部形態分類的結果，其他3組形態複合群（Neritina complex 1、Neritina complex 2與Neritina complex 4），並不呈一單系群，且不支持殼的外部形態分類的結果；（5）壁蜑螺屬2個物種各呈一單系群，支持殼的外部形態分類的結果。綜合本研究結果認為，以外部形態鑑定種類的方法不適用於石蜑螺屬與河蜑螺屬物種，除了種內形態變異往往大過於種間外，且個體可能受到表形塑性的影響，或可能有隱蔽種的存在，使得蜑螺的殼形變異更加複雜。

關鍵字

蜑螺 ； 遺傳標誌 ； 隱蔽種 ； 表形塑性

並列摘要

There are five genus of Neritidae in Taiwan and its adjacent islands, (1) Nerita Linnaeus, 1758, (2) Smaragdia Issel, 1869, (3) Clithon Montfort, 1810, (4) Neritina Lamarck, 1816, (5) Septaria Ferussac, 1807. In previous study, the taxonomy of Neritidae were based on morphological features, such as shell, operculum and animal anatomy. However, owing to wide range of morphological variation, the classification in the Neritidae is under debate. Here we present a taxonomy of the Neritidae in Taiwan and its adjacent islands based on molecular evidence. In this study, we used the mtDNA sequences of the COI and 16S genes and address the following question: Are the result of phylogenetic analysis concordant with the morphological features of the shell? Analyses showed the following results: (1) 16 species of genus Nerita concordance between molecular and morphological phylogeny (2) 2 species and Smaragdia sp. recorded in Dongsha island of genus Smaragdia concordance between molecular and morphological phylogeny. (3) 3species of genus Clithon concordance between molecular and morphological phylogeny, but one of Clithon complex was not monophyletic group that discordance between molecular and morphological phylogeny. (4) 4 species and Neritina complex 3 of genus Neritina concordance between molecular and morphological phylogeny, but Neritina complex 1, Neritina complex 2 and Neritina complex 4 were not monophyletic group that discordance between molecular and morphological phylogeny. (5) 2 species of genus Septaria concordance between molecular and morphological phylogeny. According to these results, It might be subjected to different microhabitats and revealed considerable phenotypic plasticity. In addition, it suggested that the presence of cryptic species of genus Clithon and Neritina in current taxonomic system. In conclusions, the shell morphology apparently could not provide useful information to clarify their species status for genus Clithon and Neritina.

並列關鍵字

Neritidae ； molecular evidence ； cryptic species ； phenotypic plasticity

參考文獻

Andrews E (1935) The Egg Capsules of Certain Neritidae. Journal of Morphology 57, 31-59.

Andrews E (1937) Certain Reproductive Organs in the Neritidae. Journal of Morphology 61, 525-561.

Anisimova M, Gascuel O (2006) Approximate Likelihood-ratio Test for Branches: A Fast, Accurate, and Powerful Alternative. Systematic biology 55, 539-552.

Avise JC (2000) Phylogeography: the history and formation of species. Cambridge, MA: Harvard University Press.

Baker HB (1923) Notes on the Radula of the Neritidae. Proceedings of the Academy of Natural Sciences of Philadelphia 75, 117-178.