Abstract Detail

Systematics

Goodman, Glynis [1], Kahnt, Belinda [2], Hattingh, W.N.H [3], Kuhlmann, M. [4], van der Niet, T. [5].

The genus Diascia (Hemimeridae, Scrophulariaceae s.s.) – phylogeny, biogeographical and life history patterns.

Although the fascinating mutualistic association between the southern African endemic genus Diascia (Hemimeridae, Scrophulariaceae) and its pollinator, the solitary Rediviva bee, have been the focus of numerous studies, little is known about relationships within Diascia, its origins, biogeography, and life history patterns. Of the ca. 72 species in Diascia, the majority (62.5%) are annual (section Diascia) and occur in the winter-rainfall region of the Greater Cape Floristic Region (GCFR), whereas the smaller section Racemosae (27 species) comprises mainly (81%) perennial species from the summer rainfall region of South Africa. We used DNA sequence-based phylogenies to test the monophyly of the genus Diascia and its two sections, Racemosae and Diascia, hypothesise relationships within Diascia, estimate its date of origin and interpret biogeographical and life history patterns. Nuclear ITS and combined analyses support Diascia as monophyletic, but the two main clades remain unresolved with Nemesia in the plastid trnL-trnF phylogeny. Morphology and geography reflect relationships to some extent with four of Hilliard & Burtt’s seven groups in Section Racemosae supported partially or fully. Section Racemosae is monophyletic, but sect. Diascia is paraphyletic as at least two of its members fall outside of the clade, with D. nana diverging earliest. Like many of the ‘Cape genera’, Diascia originated in the early Miocene in the GCFR and diverged Mid-Miocene with greatest diversification occurring in the Pliocene, i.e. when the Mediterranean climate in the region was well established. Unusually and contrary to Stebbins’ theory of life history evolution in plants, in Diascia the annual life history strategy has evolved into the perennial one, concomitant with its origin in the arid Succulent Karoo and Fynbos regions of the GCFR, and later dispersal to the more mesic eastern regions of South Africa.

1 - University Of The Witwatersrand, 1 Jan Smuts Avenue, Johannesburg, GT, 2050, South Africa
2 - Institute of Biology, Martin-Luther University Halle Wittenberg, General Zoology, Halle (Saale), Germany
3 - University of the Witwatersrand, 1 Jan Smuts Avenue, Johannesburg, 2050, South Africa
4 - Kiel University, , Zoological Museum, Kiel, Germany
5 - University of Kwazulu-Natal, School of Life Sciences, Centre for Functional Biodiversity, 1 Jan Smuts Avenue, Pietermaritzburg, South Africa

Keywords:
phylogenetic analysis
Biogeographical pattern
life history
evolution.

Presentation Type: Oral Paper
Session: SYSTV, Systematics V: Euasterids cont.
Location: Virtual/Virtual
Date: Thursday, July 22nd, 2021
Time: 1:00 PM(EDT)
Number: SYSTV003
Abstract ID:755
Candidate for Awards:None