Spatial phylogenetics of the native California flora

Area of Science:

• Evolutionary biology
• Botany
• Biodiversity research

Background:

• California is a global hotspot for plant biodiversity.
• The terms neo-endemism and paleo-endemism were first defined in California.
• Spatial phylogenetics allows evolutionary assessment of biodiversity patterns.

Purpose of the Study:

• To identify significant areas of neo-endemism and paleo-endemism in California.
• To evaluate biodiversity from an evolutionary perspective using spatial phylogenetics.
• To combine museum specimen data with DNA phylogenies for spatial biodiversity analysis.

Main Methods:

• Utilized a dataset of 1.39 million herbarium specimens.
• Employed a phylogeny of 1083 operational taxonomic units (OTUs) and 9 genes.
• Applied spatial randomization tests and categorical analysis of neo- and paleo-endemism (CANAPE).

Main Results:

• Identified extensive phylogenetic clustering in South Coast Ranges, Great Valley, and deserts.
• Found significant concentrations of short and long phylogenetic branches across various California regions.
• Pinpointed areas of paleo-endemism in Northwestern California and neo-endemism in the White-Inyo Range and Mojave Desert.

Conclusions:

• Geographic distribution of phylogenetic branch lengths offers new insights into California floristics.
• Arid regions show concentrated phylogenetic endemism, supporting aridity as an evolutionary stimulus.
• Findings are robust to phylogenetic uncertainty but sensitive to data sources, highlighting the need for improved distributional data.