Abstract Detail


Humphreys, Emily [1], Flores Olvera, Hilda [2], Ochoterena, Helga [2], Douglas, Norman [3], Moore, Michael [4].

Niche evolution in the Nyctagineae: a group with an ancestral affinity for gypsum?

Nyctaginaceae tribe Nyctagineae comprises 12 genera and approximately 200 species of herbs and shrubs with a global distribution but with a center of diversity in arid and semi-arid regions of southwestern North America. Gypsum endemism is remarkably common across Tribe Nyctagineae, with at least 13 species confined to gypsum; these 13 species are found in North America and in the Horn of Africa region, and represent five of the 12 genera. Moreover, there are two clades of gypsum endemics known in Nyctagineae (within the genera Acleisanthes and Anulocaulis), and in any area of gypsum soils where Nyctagineae occur, essentially all local species of Nyctagineae may be found growing on gypsum (whether they are endemics or not). Here we reconstructed a nearly complete (~85% of species) species-level phylogeny of Nyctagineae using nuclear ITS and plastid spacer regions in an effort to understand the evolution of gypsum endemism across the tribe. We then used the resulting trees to reconstruct niche evolution in the tribe for key climate and soil variables to explore correlations between gypsum affinity and abiotic niche variables. For niche evolution analyses, occurrence data from iDigBio, GBIF, and SEINet for all taxa were downloaded and cleaned for poor-quality data. Then, 19 climate variables from the Worldclim database and 11 soil variables from the ISRIC-World Soil Information database were extracted for every occurrence point and mean values were calculated for each taxon, for each variable. Niche reconstructions for each variable were conducted on the phylogenetic trees using ape and PHYtools in R. We found a minimum of eight origins of gypsum endemism across Nyctagineae on two continents. Variables related to temperature often exhibited high variability across the phylogeny, but precipitation variables were much less variable, suggesting that drought tolerance may be a key adaptation for the tribe. Among the soil variables, a relatively high pH was correlated with gypsum endemism. Although preliminary, evidence on foliar gypsum biomineralization is also presented, demonstrating that the ability to synthesize gypsum crystals in leaves may be at least partly responsible for the strong affinity of Nyctagineae to gypsum soils.

Related Links:
Origin and Evolution of Chihuahuan Desert Gypsum Endemic Plants

1 - Oberlin College, Department of Biology, 119 Woodland St, Oberlin, OH, 44074-1060, United States
2 - Instituto de Biología, Universidad Nacional Autónoma de México, Departamento de Botánica, Apdo. Postal 70-367, Coyoacán, México, DF, 04510, México
3 - University Of Florida, Biology, PO Box 118525, Gainesville, FL, 32611, United States
4 - Oberlin College, Department Of Biology, 119 Woodland St., Science Center K111, Oberlin, OH, 44074, United States

climate change
niche evolution.

Presentation Type: Oral Paper
Number: SYST II009
Abstract ID:282
Candidate for Awards:None

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