Abstract Detail


Eifler, Evan [1], Karimi, Nisa [2], Lemmon, Alan [3], Lemmon, Emily [4], Givnish, Thomas [5].

Patterns of Species Diversification in Geissorhiza (Iridaceae): Morphological and Habitat Traits Through Time.

The Greater Cape Floristic Region (GCFR) of southwestern South Africa harbors an exceptionally rich angiosperm flora with a higher proportion of endemic species than any other continental landmass, and is the biodiversity hotspot for the iris family (Iridaceae). 33 clades in 24 families account for half of GCFR diversity; most are specialized on either extremely infertile, sandy soils associated with fynbos, or on richer, heavier soils associated with renosterveld plant communities. Geissorhiza (104 described species) in Iridaceae subfamily Crocoideae is an exception and has apparently speciated extensively in both fynbos and renosterveld. It is one of the largest genera wholly restricted to the GCFR, where it occurs across a wide range of soil textures, elevations, and hydrological regimes, exhibits striking variation in floral form, and shares the geophytic habit that characterizes such a large share of the GCFR flora. In addition, the flowers of six species of Geissorhiza appear to closely mimic co-flowering irids, 68 of its species are of conservation concern, and 16 are known only from a single location on Earth.
We derived molecular phylogenies for Geissorhiza based on sequencing 436 nuclear loci (via anchored hybrid enrichment) and entire plastomes. We calibrated the plastome tree against time by embedding it in a fossil-calibrated monocot plastome phylogeny. Here we use those phylogenies to infer patterns in the evolution of morphological traits including plant height and corm size, floral form, soil characteristics, climatic niche, and habitat use through time. We report multiple switches between the inferred ancestral habitat, fynbos, and the younger renosterveld habitat but these switches were not correlated with shifts in net rates of species diversification which remained consistent through time. We also report multiple independent origins of psammophory (sand armor) in the group. In addition, we will quantify the relationship between geographic and genetic distance to begin to understand how presumed short gene-flow distances have impacted the diversification of the group. Collectively, this work sheds meaningful light on the evolution and diversification of Geissorhiza, a hallmark genus of megadiverse southwest South Africa.

1 - UW Madison, Botany, 430 Lincoln Dr., Madison, WI, 53706, United States
2 - University Of Wisconsin - Madison, Department Of Botany, 430 Lincoln Drive, Madison, WI, 53706, United States
3 - Florida State University, Scientific Computing, 89 Chieftain Way, Biology Unit 1, Tallahassee, FL, 32306, United States
4 - Florida State University, Biological Sciences, 89 Chieftain Way, Biology Unit 1, Tallahassee, FL, 32306, United States
5 - University Of Wisconsin-Madison, Department Of Botany, 315 Birge Hall, 430 Lincoln Drive, Madison, WI, 53706, United States

molecular dating

Presentation Type: Oral Paper
Number: PHYLO II010
Abstract ID:737
Candidate for Awards:None

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