Format: ORAL

Thaabiet Parker1,2, Geoge A. Verboom1, Nicola G. Bergh2, John C. Manning2, Allan G. Ellis3

1 University of Cape Town, Cape Town, South Africa. 2 South African National Biodiversity Institute Kirstenbosch Botanical Gardens, Cape Town, South Africa. 3 University of Stellenbosch, Stellenbosch, South Africa.

Evolutionary relationships in the South African daisy genus Dimorphotheca Vaill ex. Moench. have long been problematic, with historical taxonomy often being based on potentially labile morphological traits. Here we investigate the Dimorphotheca pluvialis-sinuata species complex which have historically been separated based on white vs orange ray colour alone; but show widespread variation in ray colour patterns, disc floret sculpturing and fruit characters. We present an integrated taxonomic approach utilising next-generation sequencing genetic data in conjunction with several additional lines of evidence. Plants from 191 populations were sampled from 20 a priori morphotypes which encompassed the range of morphological variation in the complex. DNA of 301 individuals were extracted for genotyping-by-sequencing (GBS) and concatenation and coalescent phylogenetic species delimitation approaches were used to assign individuals to hypothesised genetic species. Support for genetic species was further assessed using surveys of phenotypic trait variation as well as cross-pollination experiments. Results showed strong support for at least four species within the complex; with the previous use of ray colour ineffective in delimiting species. While three putative genetic species can be clearly identified and grouped based on morphological characters, the remaining species encompasses a wide range of diverse morphotypes which exhibit variation on a geographic cline. Phylogenetic patterns suggest this may be due to repeated range expansion and subsequent serial founder effects, and we further assess this using a clinal genomic analysis which incorporated pollinator observations as a potential selective regime. This study provides a framework for untangling complex taxonomic questions and emphasises understanding of evolutionary process in reclassification.