Professor Thomas J. Givnish

Givnish Lab Group
Graduate students and post-docs in my lab explore several aspects of plant ecology, evolution, and biogeography, from the determinants of shade tolerance in temperate forest trees to the causes of inverted treelines, the role of mycorrhizae in promoting vascular plant diversity in natural communities, the spatial scales of of genetic differentiation and incipient mating barriers in tropical forest trees and temperate forest herbs, and the metapopulation dynamics of endangered species: Jonathan Coop (Ph.D. candidate - Subalpine treelines in the southern Rocky Mountains) *Jillian Henss (Ph.D. candidate - Adaptive radiation in Catopsis)* *Kendra Millan (Ph.D. candidate - Phylogeography of the Trillium erectum* complex) Tara Suring (M.S. candidate - Metapopulation dynamics of the federally endangered Pitcher's thistle) Terra Theim (Ph.D. candidate - Spatial scales of genetic differentiation and incipient mating barriers in gap vs. understory species of Psychotria) Frank Landis (Ph.D. - Relationships among arbuscular mycorrhizal fungi, plants, and environmental conditions in Wisconsin oak savannas) Omar Lopez (Post-doctoral associate - Leaf phenology and hydraulic conductivity as determinants of shade tolerance in trees of the southern Appalachians Photographs:** TOP - Inverted subalpine treeline in the Valles Caldera National Preserve, northern New Mexico (JD Coop). BOTTOM - Platanthera leucophaea (Orchidaceae), one of the most rapidly disappearing species in Midwestern wet prairies (TJ Givnish); ripening fruit of Psychotria horizontalis (Rubiaceae), native to densely shaded rainforest understories in Central America (Trees of the Panama Canal Area: http://ctfs.si.edu/webatlas/plant.photos/psycho.frut1.jpg); spore of Scutellospora calospora (Glomales), found in Midwestern oak savannas (FC Landis); shade-tolerant saplings of Ostrya virginica (Betulaceae) leafing out under the as-yet-unopened canopies of Quercus rubra (Fagaceae) and other late-leafing, shade-intolerant trees at Clifty Falls Park, IN (TJ Givnish); carnivorous epiphyte Catopis berteroniana (Bromeliaceae), native to the sunlit tops of trees from southern Florida to the West Indies, Central America, and northern South America (web image); and Trillium flexipes (Melanthiaceae), a wide-ranging, Midwestern element of the Trillium erectum complex, including several narrow endemics to the southern Appalachians and two other wide-ranging taxa (T. cernuum and T. erectum) (TJ Givnish).

Omar Lopez (Post-doctoral associate - Leaf phenology and hydraulic conductivity as determinants of shade tolerance in trees of the southern Appalachians

Photographs: TOP - Inverted subalpine treeline in the Valles Caldera National Preserve, northern New Mexico (JD Coop). BOTTOM - Platanthera leucophaea (Orchidaceae), one of the most rapidly disappearing species in Midwestern wet prairies (TJ Givnish); ripening fruit of Psychotria horizontalis (Rubiaceae), native to densely shaded rainforest understories in Central America (Trees of the Panama Canal Area: http://ctfs.si.edu/webatlas/plant.photos/psycho.frut1.jpg); spore of Scutellospora calospora (Glomales), found in Midwestern oak savannas (FC Landis); shade-tolerant saplings of Ostrya virginica (Betulaceae) leafing out under the as-yet-unopened canopies of Quercus rubra (Fagaceae) and other late-leafing, shade-intolerant trees at Clifty Falls Park, IN (TJ Givnish); carnivorous epiphyte Catopis berteroniana (Bromeliaceae), native to the sunlit tops of trees from southern Florida to the West Indies, Central America, and northern South America (web image); and Trillium flexipes (Melanthiaceae), a wide-ranging, Midwestern element of the Trillium erectum complex, including several narrow endemics to the southern Appalachians and two other wide-ranging taxa (T. cernuum and T. erectum) (TJ Givnish).