Abstract Detail


Eifler, Evan [1], Lemmon, Alan [2], Lemmon, Emily [2], Givnish, Thomas [1].

Novel Phylogenomics in Geissorhiza (Iridaceae): Preliminary results from the Cape Floristic Region.

The Greater Cape Floristic Region (GCFR) of southwestern South Africa harbors an exceptionally rich angiosperm flora with ~9000 species inhabiting an area of only 90,000 km2. Thirty-three clades account for half this diversity; most are specialized on either extremely infertile, sandy soils associated with fynbos, or on much richer, heavier soils associated with renosterveld plant communities. Geissorhiza (106 described species, 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 bulbous habit that characterizes such a large share of the GCFR flora. The flowers of eight species of Geissorhiza appear to closely mimic co-flowering irids, sixty-eight of its species are of conservation concern, and sixteen are known only from a single location on Earth.  Our research opens a new window on plant evolution in the GCFR through the lens of Geissorhiza. We have derived molecular phylogenies for 84 species of Geissorhiza, 10 Hesperantha, and 2 Babiana species as outgroups, based on sequencing 436 nuclear loci and entire plastomes. Here we present preliminary phylogenomic results. Our nuclear phylogenomic data suggest that Geissorhiza is embedded within a paraphyletic Hesperantha with a few misplaced taxa. Geissorhiza comprises two major clades – one smaller, with a lower net diversification rate, largely composed of low-elevation species, the other much larger, with a higher net diversification rate, representing a greater diversity of ecologies presumed. The radiation is marked by multiple colonizations of renosterveld and fynbos and transitions between the two, at least four colonizations of semi-arid karoo, at least three of waterfall habitats, and multiple origins of floral mimicry.

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1 - University Of Wisconsin-Madison, Department Of Botany, 430 Lincoln Drive, Madison, WI, 53706.0, United States
2 - Florida State University, 89 Chieftain Way, Biology Unit 1, Tallahassee, FL, 32306, United States

character evolution.

Presentation Type: Oral Paper
Session: PHYL3, Phylogenomics III
Location: Virtual/Virtual
Date: Friday, July 31st, 2020
Time: 10:45 AM
Number: PHYL3004
Abstract ID:873
Candidate for Awards:None

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