Significance of variation and evaluation of potential characters in three morphologically similar species of Barleria sect. Barleria (Acanthaceae) in southern Africa

• Published in: Plant systematics and evolution Vol. 304; no. 1; pp. 77 - 92
• Main Authors: Nyirenda, Florence C., Balkwill, Kevin
• Format: Journal Article
• Language: English
• Published: Vienna Springer-Verlag GmbH 01.01.2018; Springer Vienna; Springer Nature B.V
• Subjects: Barleria; Biomedical and Life Sciences; Cluster analysis; Gene flow; Gene mapping; Geographical distribution; Life Sciences; Morphology; Ordination; Original Article; Plant Anatomy/Development; Plant Ecology; Plant Sciences; Plant Systematics/Taxonomy/Biogeography; Species; Variation; South Africa; Cluster analysis; Continuities; Morphological characters; Discrete; Ordination
• ISSN: 0378-2697; 1615-6110; 2199-6881
• DOI: 10.1007/s00606-017-1452-5

The variation exhibited within three species of Barleria (B. bechuanensis, B. irritons and B. jubata) was studied to establish whether it was discrete or continuous. Morphological characters were examined and recorded in matrices. Cluster analysis was employed to impose a hierarchical non-overlapping association among operational taxonomic units (OTUs) while ordination was used to establish whether the variation was discrete or continuous. Discrete characters were determined from quantitative morphological data using box and whisker plots. Locality information for the OTUs was obtained from herbarium labels and used to generate maps to illustrate geographic distribution of taxa. Cluster analysis and ordination demonstrated that there was discrete variation within Barleria bechuanensis, B. irritons and B. jubata, which each split into two distinct clusters, although box and whisker plots illustrated that many quantitative characters overlapped within and between species. Since clear morphological gaps between clusters are assumed to be indicators of breaks in gene flow, the distinct clusters were recognised at species level.