以限制酶點位核酸定序法針對東方蜜蜂以及蜂蟹蟎族群分化之探討

RAD-seq species delimitation and population genetic differentiation of the honeybee Apis cerana and its ectoparasitic mite Varroa destructor

邱奕凡(Yi-Fan Chiu)

指導教授 ： 蘇詠超

高雄醫學大學/生命科學院/生物醫學暨環境生物學系碩士班/碩士(2020年)

摘要

蜜蜂（Apis）是自然生態環境以及農作系統當中重要的傳粉者，他們對於生態以及經濟上的影響不容小覷。過去的文獻指出東方蜂（Apis cerana）的外寄生蟲——蜂蟹蟎（Varroa destructor）出現宿主轉移的現象，由於不同宿主對於蜂蟹蟎的抵抗機制尚未成熟，造成新宿主西方蜂（Apis mellifera）族群間蟎害的快速傳播，同時也因為蜂蟹蟎攜帶病毒的特性，被認為是近年蜂群減少的主因之一，嚴重打擊全球蜜蜂產業。因此，明確的蜂種分類變得非常重要，一旦蜂蟹蟎轉移至新的蜂種上，極有可能因為新宿主對於蜂蟹蟎的抵抗機制缺乏而導致蜂群減少的狀況。因此，在本研究當中，我們使用限制酶點位核酸定序法（Restriction-site associated DNA sequencing，RAD-seq）偵測亞洲不同地區東方蜂群以及在不同宿主上的蜂蟹蟎族群狀況。在蜜蜂族群實驗當中，我們使用亞洲地區蜜蜂族群，包含亞洲大陸、印度、巽他古陸、菲律賓區域，進行分化檢測。而在蜂蟹蟎實驗當中，我們使用來自越南以及台灣，寄生於東方蜜蜂以及西方蜜蜂的蜂蟹蟎族群為模型，檢測族群之間差異。根據在本論文的兩個章節當中的RAD-seq數據，我們發現亞洲東方蜂至少已分化為四個物種，蜂蟹蟎族群則是出現不同宿主族群間的雜交狀況，代表蜂蟹蟎並不受宿主物種影響，區域性的蜂蟹蟎可能危害不同物種的宿主，仍有機會感染不同蜂群。本研究當中的結果可以作為未來在蜜蜂族群保育，以及蟎害防治上的基礎，協助改善蜜蜂族群的管理方針，降低蜂蟹蟎對於蜂種的危害。

關鍵字

蜂 ； 親緣基因體學 ； 物種界線 ； 種化 ； 基因體學 ； 瓦蟎 ； 雜交 ； 族群遺傳學

並列摘要

Honeybees (genus Apis) are keystone species for pollination in agricultural systems and ecosystems, which constitute their important roles in ecology and economy. Varroa mites are the obligate ectoparasites across Apis honeybees. Varroa mites of Apis cerana, Varroa destructor, have shifted to the new host, Apis mellifera, and have caused substantial damage to the world’s apiculture. The delimitations of those honeybees and their parasites are important knowledge for entire apiculture, especially for the conservation plans and management of honeybees and the control of Varroa mites. We used the restriction-site associated DNA sequencing (RAD-seq) approach to delimitate the geographic populations of Apis cerana, and to detect the isolation or hybridization among V. destructor collected from different colonies across landscapes, from geographic areas, and from different hosts. For Apis cerana, we genotyped 95 Apis cerana from different locations across Asia, i.e., Asian mainland, India, Sundaland, and Philippines, to conduct the species delimitation analyses. And we genotyped 50 Varroa destructor for revealing the hybridization between populations from Vietnam and Taiwan that hosted by Apis cerana or Apis mellifera. Our RAD-seq results indicated that the species diversity in the Apis cerana complex in Asia was underestimated. At least four lineages showing discontinued gene flow. The Varroa mites were the hybridized populations from multiple ancestors, i.e., the genome of Varroa mites are still mixing no matter the hosts or localities they parasitized in Vietnam or Taiwan. The results of the two research chapters in this thesis showed that (1) in broader geographic areas, the honeybees in the Apis cerana complex should be divided into four geographic species; (2) in a fine geographic scale, the local Varroa ectoparasite communities might have higher weight in regarding the infestation to the honeybee colonies than the Varroa mites of specific haplotypes based on the results of the mite population genomics structure analyses.

並列關鍵字

Bee ； Phylogenomics ； Species boundary ； Speciation ； Genomics ； Varroa mite ； Hybridization ； Population genetics

參考文獻

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