Digital Data in Biodiversity Research Conference

Niche divergence is considered an important driver of speciation and diversification that has consequences for species coexistence. By characterizing niches of species across a whole group it becomes possible to assess niche differences among closely related species and gain insight into the role niches play in lineage diversification. To evaluate the role of niche differentiation in lineage diversification, I studied the American Clade of Asclepias (milkweeds), which contains approximately ~130 species. These species exhibit a broad range of ecological variation and can be found across much of North, Central, and South America. I hypothesized that 1) species diverged mainly along niches axes associated with climate (temperature and precipitation) with a small contribution from soil characteristics, and 2) niche overlap among American Asclepias are not indicative of niche conservatism. Here, I characterized niches by utilizing 19 bioclimatic variables, elevation, % clay content, % silt content, % sand content, coarse fragment content, nitrogen content, pH, and electrical conductivity. I used multivariate analyses, including principal component analysis (PCA), and ecological niche modeling, to characterize niches and evaluate species differences. The degree of niche overlap between species was measured using Warren’s I and to determine signal for niche conservatism a Mantel test was used.