岩桐屬三維花朵形狀變異分析以及共祖形狀之重建

Abstract

花朵形狀變異對於花卉產業來說是一個有趣的研究主題。岩桐屬Corytholoma擁有高度多樣的花朵形狀。量化花朵形狀變異是園藝學家和植物學家分析花卉形狀的重要環節。此外，在演化樹中花朵形狀推估的演變也是個引人注目的議題。揭露共祖花朵形狀可以幫助我們去探究現存物種的多樣性與花朵形狀變異之間的關係。在此研究中，利用三維影像與幾何形態學去量化花朵形狀變異。藉由微計算機斷層掃描技術得到三維花朵影像。特徵點在三維影像上半自動點選，以描述花朵形狀。利用幾何形態學來決定主要的花朵形狀變異。再藉由主要的花朵形狀變異來定義形態上的特徵。透過權重平方簡約法與現存花朵形狀重建共祖花朵形狀。以呈現Corytholoma花朵形狀的演化。最後，此研究提出一個方法在三維中量化岩桐屬花朵形狀變異與重建共祖花朵形狀。

Floral shape variation is an intriguing research topic for floricultural industry. Floral shape is highly diverse in clade Corytholoma of genus Sinningia. Quantifying floral shape variations is an important segment for horticulturists and botanists to analyze the floral shapes. Additionally, putative transition of floral shape in phylogenetic tree is an attractive issue. Revealing the flower shapes of the putative ancestors may help us to explore the relationship between diversification of extant species and floral shape variation. In the study, the floral shape variations were quantified using the acquired 3D imaging, and geometric morphometrics. The three-dimensional (3D) images of flower specimens were obtained using micro-computed tomography. Landmarks, characteristic points of the flowers, were identified semi-automatically on the 3D images to describe the flower shapes. Major shape variations of the flowers were determined using geometric morphometrics. Morphological traits of the flowers were defined according to the major shape variations. Ancestral floral shapes were reconstructed using weighted squared-change parsimony and the extant floral shapes. Evolution of the floral shapes in clade Corytholoma was revealed. In conclusion, this study showed a method to quantify the floral shape variations and reconstruct ancestral floral shapes in 3D for genus Sinningia.