Thomas Givnish

Thomas Givnish

University of Wisconsin-Madison

Henry Allan Gleason Professor of Botany

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Looks like a very exciting phenomenon, Evan!
Oct 05, 2017
Geissorhiza: an evolutionary case study in the Cape Floristic Region
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Interesting that G. brevituba has sticky leaves that collect sand! This is a rare trait, but occurs in several families, and has only recently been proposed as an anti-herbivore defense. Remarkable that it occurs in Geissorhiza, and it'll be interesting to see if this species is unique in this respect within the genus, or whether close relatives – or other species growing on sand – have this same rare trait!
Oct 02, 2017
Geissorhiza: an evolutionary case study in the Cape Floristic Region
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Hope this is funded!!
Aug 30, 2017
Geissorhiza: an evolutionary case study in the Cape Floristic Region
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Ah - it turns out that ALL species of Cyanea are restricted to the Hawaiian Islands. Presumably, other islands in the Pacific are simply too far away to colonize. What is truly surprising is that 93% of Cyanea species are restricted to individual islands, such as Kaua`i, O`ahu, Maui, and the Big Island of Hawai`i. This despite the fact that these islands are quite close to each other, and despite Cyanea having fleshy fruits eaten by birds that should disperse the seeds far and wide. But most Cyanea species grow in the understory of tropical forests, and most understory birds are notoriously sedentary. As a consequence, we believe that – as with a number of understory genera of flowering plants – populations of individual species can undergo genetic differentiation at small spatial scales, leading ultimately to high rates of speciation and narrowly distributed species – generating a lot of biological diversity, but leaving many of the resulting species highly prone to extinction as well.
Oct 02, 2016
Evolution and geographic spread of Cyanea, the largest genus of native Hawaiian plants
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