Official websites use .gov
A
.gov website belongs to an official
government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you've safely
connected to the .gov website. Share sensitive
information only on official, secure websites.
Zygophyllaceae species diversity as functions of aridity index (a) and mean net diversification rate per geographical unit (b) in the world and the five biogeographic regions. The vertical dashed line in (a) indicates the threshold of aridity index (0.65) for the definition of drylands. Regression lines (red) based on generalized linear models (GLM) with Poisson residuals were drawn when the relationships were significant at p < 0.05.
