Oral Paper

         Biogeography

Climatic niche differentiation of African acacias (Senegalia, Vachellia; Fabaceae)

Presenting Author
Joseph Charboneau
Description
Following the retypification of non-monophyletic Acacia Mill. s.l., the ca. 140 acacia species found in Africa are now about evenly split between two genera: Senegalia Raf. and Vachellia Wight & Arn. The extant species of Senegalia and Vachellia both date from common ancestors that lived about 5-8 Mya, concurrent with the rise of C4 grasses and increasing diversity of large mammalian herbivores. As many of these species became established in African savannas and came to dominate them, their seedlings have needed to overcome stressors such as competition with grasses, herbivory, fire, and drought. Differences among species in geographic range, phenotypic traits, and ecological interactions suggest species likely vary in their tolerances to these stressors. We will use GBIF occurrence data (including iNaturalist observations as well as herbarium specimens) to examine species’ differences in climatic niche using ordination methods and niche modeling. We also will compare species-specific tolerances to stressor treatments in a common garden experiment in Arusha, Tanzania to tolerances estimated from occurrence data.