Elliptic Fourier Analysis of Leaf Shape Plasticity in the Billy Goat Weed geratum conyzoides L. (Asteraceae) from Agricultural Farms in Claveria, Misamis Oriental,Philippines
The Billy goat weed, Ageratum conyzoides L., is a weed of agricultural significance and is one of the reasons for reduction in crop productivity in Southeast Asia. What enables this species to displace and successfully invade new environments? A review of current hypotheses about invasiveness in weeds emphasizes its high association with plasticity in traits and the evolutionary reallocation of resources to growth, reproduction and competition. In this study, plasticity with regards to the shapes of a total of 997 leaves of the Billy goat weed collected from six agricultural sites in Claveria, Misamis Oriental, Philippines was assessed using the method of elliptic Fourier analysis. The leaves were scanned at uniform dpi and the contours of each leaf summarized as chain codes were transformed into a total of 80 elliptic Fourier coefficients. These coefficients were used as morphometric variables to test for significant differences in the leaves collected from the six populations. Principal component analysis was performed on the shape data to summarize the information in a number of components that represent independent shape components. Results of the analysis returned a total of six significant principal components (PCs) that were good measures of the leaf-aspect ratio and shapes of the base and apex. Of the five principal components, PC3 described the asymmetries in the shapes of the leaves. Test for significant differences in the shapes of the leaves from the six populations were done using a nonparametric analogue of the analysis of variance (Kruskal-Wallis) of the principal component scores. Post hoc tests were also performed to determine which among the populations differed significantly. Results showed significant differences in a total of four independent shape characteristics of the leaves. However, no significant differences in leaf asymmetry were found among all sites. The results of this preliminary study demonstrates the potential of modern multivariate techniques using shape-based methods on digital images to achieve high efficiency performance in leaf shape description and could be used hi future studies in correlating shape variations with environmental heterogeneity.
Ageratum conyzoides L Billy goat weed elliptic Fourier analysis lasticity
Dennis A. Mugot Mark Anthony J. Torres Ruben F.Amparado Jr.Cesar G. Demayo Jessie G. Gorospe
Misamis Oriental State College of Agriculture and Technology 004 Claveria, Misamis Oriental, Philipp Department of Biological Sciences College of Science and Mathematics MSU-Iligan Institute of Technol Department of Biological Sciences College of cience and Mathematics MSU-Iligan Institute of Technolo School of Graduate Studies,MSU-Naawan, Naawan, Misamis Oriental, Philippines
国际会议
昆明
英文
395-400
2010-10-17（万方平台首次上网日期，不代表论文的发表时间）