A phylogenetic study of the genus Dianthus L. (Caryophyllaceae) in South Africa

Abstract

This study addresses the phylogenetic relationships within the genus Dianthus in South Africa, employing molecular analysis approach and the distribution pattern of the genus. We extracted DNA and sequenced South African taxa which were then added into other Dianthus sequence data including Petrorhagia species (outgroup) from GenBank. A robust phylogenetic tree comprising of three plastids (trnH-psbA, trnK-matK and trnK-psbA) and ITS nuclear region was assembled based on 94 taxa of Dianthus species and Petrorhagia using Mr Bayes analysis. Furthermore, we generated the distribution map for each Dianthus species using QGIS, points extracted from BRAHMS database. Our results have revealed Dianthus as monophyletic when Petrorhagia was used as an outgroup (s). Four strongly supported clades were identified (Africa Lineage, Eurasian radiation, Section Verruculosi and Section Armerium), indicating geographical distinctions. We identified potential discrepancies, notably in the placement of D. mooiensis and D. namaensis. An unexpected relationship between D. thunbergii and D. bolusii was also highlighted, challenging current morphological classifications. Defined clades were further observed within African Dianthus (Ethiopia & Northern African species; BS/100), and Western & Eastern region of South Africa; BS/100), while two subclades (BS/100 & BS/72) were observed within the South African clade. Additionally, ITS generated unsupported and unresolved trees independently, as did the three plastids (trnH-psbA, trnK-matK, and trnK-psbA). The identified clades and unresolved species placements warrant further investigation, possibly through additional molecular gene markers or broader taxon sampling. This study sets the groundwork for future research aimed at resolving the taxonomic revision of Dianthus in South Africa.