Abstract Detail

Biogeography

Baldwin, Bruce G. [1], Thornhill, Andrew [2], Freyman, William A. [3], Ackerly, David [4], Mishler, Brent D. [5].

Hotspots of species richness and endemism in the California flora.

California’s vascular flora is the most diverse and threatened in North America north of Mexico, in part because much of that diversity is highly range-restricted within the state. Previous studies of spatial patterns of Californian plant diversity have delimited study regions of various size, shape, and number based on distributional data derived from floristic descriptions for a subset of species. As part of the ongoing California Plant Phylodiversity Project, we revisited patterns of species richness and endemism in the California flora based on objective spatial units (15 km grid cells), the full vascular flora as treated in the Jepson eFlora, and specimen-based distributional data from the Consortium of California Herbaria and other collection databases (1.38 million records), using the Biodiverse software. Results for overall richness, weighted endemism (inverse range weighting of species), corrected weighted endemism (weighted endemism corrected for richness within a cell), and a randomization test for significantly high endemism per cell allowed for an unusually fine-grained perspective on hotspots of endemism and diversity in California. High species richness was sometimes associated with significantly high endemism (e.g., in the Sierra Nevada and parts of central-western and northwestern California) but often not. Such counter-examples include Stebbins and Major’s (1965) main endemism hotspot, southwestern California, where species richness is high across much of the Peninsular and Transverse ranges but significant endemism is highly localized within those areas, mostly to the San Jacinto and San Bernardino mountains. In contrast, species richness is low in the Channel Islands, where endemism is significantly high, as also discovered for much of the Death Valley region of the California desert. Differences between our findings and those in previous studies appear to be less attributable to the proportion of species sampled across the flora than to the source and scale of distributional data for those species, as well as recent refinements in analytical methods.

Related Links:
California Plant Phylodiversity Project

1 - University Of California Berkeley, JEPSON HERB & DEPT INTEGR BIOL, 1001 Valley Life Sciences Building, MC 2465, Berkeley, CA, 94720-2465, USA
2 - University of California, Berkeley, University and Jepson Herbaria, 1001 Valley Life Sciences Building # 2465, Berkeley, CA, 94720-2465, USA
3 - University of California Berkeley, Jepson Herbarium and Department of Integrative Biology, 1001 Valley Life Sciences Bldg. #2465, Berkeley, CA, 94720-2465, USA
4 - University of California, Berkeley, Integrative Biology and Jepson Herbarium, 3040 Valley Life Sciences Bldg., Berkeley, CA, 94720-3140, USA
5 - University Of California, Berkeley, University and Jepson Herbaria, 1001 Valley Life Sciences Building, Berkeley, CA, 94720-2464, USA

Keywords:
biodiversity hotspots
California
species diversity
endemism
flora
species richness.

Presentation Type: Oral Paper
Session: 30, Biogeography I
Location: 203/Savannah International Trade and Convention Center
Date: Tuesday, August 2nd, 2016
Time: 4:45 PM
Number: 30013
Abstract ID:374
Candidate for Awards:None