臺灣、印度和歐洲月孔沙錢海膽生物地理學

Abstract

論文分為幾個獨立研究章節，每個章節都採用了不同的方法論來深入探討沙錢海膽生物地理演化與遷徙模式。通過整合不同的分析技術，本研究提供了對沙錢海膽如何隨著時間的推移而擴散和適應的全面理解。每一章節都專注於生物地理學的特定研究方向，包括遷徙事件、環境因素的影響以及生物互動，從而提供了對沙錢海膽分佈演化過程的多面向觀點及深入研究。 形態計量學方法，包括傳統測量和幾何形態計量學分析，可應用於野柳地質公園內現地保存不完整之星楯海膽科沙錢海膽化石標本研究中。幾何形態計量學分析揭示了所研究的兩個屬有明顯離散聚集，即使在最少三個標記點數量的數據分析結果也是如此。這一方法的有效性並獲得使用傳統線性測量之獨立研究結果進一步證實。因此，本研究加強了這些方法在臺灣中新世沙錢海膽化石群落屬級識別中的可信度和可靠性。 對捐贈給臺大地質科學系之臺灣及全球其他地區化石海膽收藏進行系統分支分析，產生了一個追溯演化關係和生物地理模式的海膽系統發育樹。通過這一根據形態特徵而產生的系統發育樹與現有分子數據所得到的系統演化樹進行比較，對所研究標本的演化模式有了更清晰的理解。這進一步強調了採用多種方法來全面認識演化關係的重要性。 根據Seilacher（1979年）提出的沙錢海膽全球遷徙分佈路徑假設，本研究重新評估了古地理空間中沙錢海膽遷徙，通過檢查來自三個不同地理區域的標本。對臺灣中新世野柳地質公園化石標本進行了詳細拍攝以確保全面代表性，印度標本則通過親自參與野外考察獲得，歐洲標本則通過現有出版文獻圖片進行分析。應用了傳統和幾何形態計量學方法，結果得到以下一致的結論。研究發現印度標本與臺灣標本的親緣關係比與地中海標本的親緣關係更為密切，代表有與原先假設不同的新遷徙路徑。這項研究突顯了中新世沙錢海膽遷徙模式的全新視角。 理解海膽的捕食模式和生物互動提供了對捕食者和獵物之間動態演化的洞察。從印度和臺灣化石標本中有收集到些許帶有鑽孔的沙錢海膽化石，這些孔洞證明有捕食者-獵物關係存在。對更新世四溝層貝類鑽孔進行初步研究提供了捕食者-獵物關係的研究背景，因為與貝類中更為均勻的模式相比，海膽中觀察到多樣的鑽孔形式，這使得大規模量化海膽鑽孔研究變得複雜。儘管如此，本研究標誌著第一次對鑽孔強度、數量、位置以及四溝層貝類中不完全鑽孔的出現進行量化樣本研究，為臺灣貝類化石鑽孔研究發表在國際期刊之首例。根據碗公狀鑽孔的普遍性和研究中所鑑定的玉螺標本，確定更新世四溝層中小錐螺Turritella cingulifera的主要捕食者是玉螺科軟體動物。 總結來說，這項論文工作有助於理解沙錢海膽生物地理學和演化歷史，強調了多面向方法論的必要性。研究結果提供了關於這些海膽在不同地理區域遷徙和演化的洞察，並為其他海洋無脊椎動物的生物地理研究樹立了先例。未來的研究可以通過納入更多地區和完善方法來進一步探索全球海膽綱演化和生物地理學。

This study is structured into several distinct chapters, each employing a variety of methodologies to delve into the biogeographic evolution and migration patterns of clypeasteroids. By integrating different analytical techniques, the research provides a comprehensive understanding of how these organisms have dispersed and adapted over time. Each chapter focuses on specific aspects of biogeography, ranging from migration events to the influence of environmental factors as well as biotic interactions and thus offering a multifaceted view of the evolutionary processes shaping the distribution of clypeasteroids. Morphometric methods, encompassing both traditional and geometric morphometric analyses, were utilized in the case study focusing on the generic-level identification of Astriclypeidae based on incomplete onsite specimens from Yehliu Geopark. The geometric morphometric analysis revealed distinctive clustering for the two genera studied, even with a minimal number of landmark points. The efficacy of this method is further corroborated by the results of an independent study employing traditional linear measurements. Consequently, this research reinforces the credibility and reliability of these methods for the generic-level identification of sand dollar specimens. The application of cladistic analysis to the NTUG-donated fossil echinoid collections from Taiwan and other regions worldwide has yielded a phylogenetic tree that traces evolutionary relationships and biogeographic patterns through the examination of morphological characters. By comparing this morphological phylogenetic tree with existing molecular data, a clearer understanding of the evolutionary patterns within the studied specimens emerges. Thus, underlines the relevance of adopting multiple approaches to comprehensively perceive evolutionary relationships. The sand dollar migration in the paleogeographic space hypothesized by Seilacher (1979) has been reevaluated in this study by examining specimens from three distinct geographic regions along the proposed migration pathway. Miocene specimens from Taiwan were meticulously photographed onsite to ensure comprehensive representation, Indian specimens were acquired through a dedicated field expedition, and European specimens were analyzed using existing published literature. Both traditional and geometric morphometric methods were applied and obtained congruent results. The findings reveal that the Indian specimens exhibit a closer affinity to the Taiwanese specimens than to the Mediterranean specimens, suggesting an alternative migration route to the one originally hypothesized. This study highlights a novel perspective on the migration patterns of Miocene sand dollars. Understanding predation patterns and biotic interactions in echinoids provides insight into the evolutionary dynamics between predators and prey. Fossil sand dollars with drill holes, indicating predator-prey relations, were collected from India and Taiwan. A pilot study on mollusk drill holes from the Pleistocene Szekou Formation provided additional context since, diverse drillhole forms are observed in echinoids in comparison with the more uniform patterns in mollusks, complicating large-scale quantification efforts for echinoid drill holes. This study marks the first bulk sample study on drilling intensity as well as the presence of turritellines with incomplete drill holes in Szekou mollusks documenting the first example from Taiwan. The primary predators of Turritella cingulifera in the Pleistocene Szekou Formation are identified as naticids, based on the prevalence of parabolic drill holes and the presence of naticid specimens by the study. Overall, this work contributes to the understanding of the biogeography and evolutionary history of keyhole sand dollars, emphasizing the importance of multi-faceted methodological approaches. The findings offer insights into the migration and evolution of these echinoids across different geographical regions, and set a precedent for similar biogeographic studies in other marine invertebrates. Future research could expand by incorporating additional regions and refining methodologies to further explore overall echinoid evolution and biogeography.