Các mối quan hệ phát sinh chủng loài của động vật thủy sinh nhờ dữ liệu genom ti thể

Springer Science and Business Media LLC - Tập 13 - Trang 1-18 - 2013
Ehsan Kayal1,2, Béatrice Roure3, Hervé Philippe3, Allen G Collins4, Dennis V Lavrov1
1Dept. Ecology, Evolution, and Organismal Biology, Iowa State University, Ames, USA
2Department of Invertebrate Zoology, National Museum of Natural History, Smithsonian Institution, Washington, USA
3Dept. Biochimie, Fac. Médecine, Université de Montral, Pavillon Roger-Gaudry, Montral, Canada
4National Systematics Laboratory of NOAA’s Fisheries Service, National Museum of Natural History, MRC-153, Smithsonian Institution, Washington, USA

Tóm tắt

Cnidaria (san hô, anemon biển, thủy tức, sứa) là một ngành động vật thủy sinh tương đối đơn giản, được đặc trưng bởi sự hiện diện của cnidocyst: một tế bào chứa một bào quan hình bao lớn với một ống xoay ngược (cnida). Các loài trong Cnidaria có chu trình sống liên quan đến một hoặc cả hai hình thái cơ thể khác nhau, thường là polyp sống đáy có thể là thuộc địa hoặc không, và medusa thường sống trôi nổi chủ yếu là đơn độc. Chương trình phân loại hiện tại chia Cnidaria thành hai tập hợp chính: Anthozoa (Hexacorallia + Octocorallia) - các động vật có polyp sinh sản và không có giai đoạn medusa - và Medusozoa (Cubozoa, Hydrozoa, Scyphozoa, Staurozoa) - các động vật thường có giai đoạn medusa sinh sản. Các mối quan hệ được giả thuyết giữa các taxa này tác động lớn đến việc hiểu lịch sử tiến hóa các đặc điểm của Cnidaria. Chúng tôi đã mở rộng việc phân tích các bộ genom ti thể của Cnidaria, đặc biệt là từ Medusozoa, để đánh giá lại các mối quan hệ phát sinh chủng loài trong Cnidaria. Các phân tích phát sinh chủng loài của chúng tôi dựa trên tập dữ liệu mitochogenomic hỗ trợ nhiều giả thuyết trước đó, bao gồm đơn nguyên của Hexacorallia, Octocorallia, Medusozoa, Cubozoa, Staurozoa, Hydrozoa, Carybdeida, Chirodropida và Hydroidolina, nhưng bác bỏ đơn nguyên của Anthozoa, cho thấy rằng mối quan hệ Octocorallia + Medusozoa không phải là kết quả của thiên lệch lấy mẫu như đã đề xuất trước đó. Hơn nữa, các phân tích của chúng tôi trái ngược với Scyphozoa [Discomedusae + Coronatae], Acraspeda [Cubozoa + Scyphozoa], cũng như giả thuyết rằng Staurozoa là nhóm chị em với tất cả các medusozoan khác. Dữ liệu genom ti thể của Cnidaria chứa tín hiệu phát sinh chủng loài có thông tin cho việc hiểu lịch sử tiến hóa của ngành này. Các cây phát sinh chủng loài dựa trên mitogenome, bác bỏ đơn nguyên của Anthozoa, cung cấp thêm chứng cứ cho giả thuyết polyp đầu tiên. Bằng cách bác bỏ các giả thuyết truyền thống về Acraspeda và Scyphozoa, những phân tích này gợi ý rằng các đặc điểm hình thái chung trong các nhóm này là plesiomorphy, có nguồn gốc từ nhánh dẫn đến Medusozoa. Việc mở rộng dữ liệu mitogenomic cùng với những cải tiến trong phương pháp suy diễn phát sinh chủng loài và việc sử dụng các dấu hiệu nhân nuclê sẽ nâng cao hơn nữa hiểu biết của chúng ta về các mối quan hệ phát sinh chủng loài và sự tiến hóa đặc điểm trong Cnidaria.

Từ khóa

#Cnidaria #phân loại #mối quan hệ phát sinh chủng loài #mitogenome #polyp đầu tiên #Hexacorallia #Octocorallia #Medusozoa

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