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Morrison, Glen [1], Saavedra, Natalie [2], Huang, Yi [3], Sanders, Andrew [4], Parker, V. T. [5], Keeley, Jon [6], Stoughton, Thomas [7], Litt, Amy [8].

Genetic differentiation among manzanitas species: distinct species, geographic groups and introgression.

The manzanitas are evergreen shrubs and small trees in the genus Arctostaphylos Adans. (Ericaceae), the most species-diverse woody genus in the California Floristic Province (CFP). All sixty manzanita species occur in the CFP, with most species occurring only within the CFP, and around half the species having very restricted ranges within the region. Arctostaphylos is distinct as a group, and its species are known for their colorful red bark, twisting branches, and urn-shaped flowers. However, species boundaries in the manzanitas have long been a subject of debate among taxonomists, due to morphological similarity among many species, interspecific hybridization, and introgression, rendering the manzanitas a long-term “problem group”. In this study, we used double digest restriction site-associated DNA sequencing (ddRADseq), and a chromosome-scale genome assembly, to generate genome-wide data for twenty-two manzanita species, including multiple individuals per species. We used genetic distance-based and ordination methods to assess genetic differentiation among the sampled species. Preliminary results show that many species can be genetically distinguished, while others appear genetically intermixed with other species in geographically coherent species clusters. One cluster of apparently genetically intermixed species is composed of endemic species of the Sierra Nevada, while another is composed of six narrow-ranged endemics of the Central Coast region, A. obispoensis, A. luciana, A. pilosula, A. silvicola, A. morroensis, and A. montereyensis. One polytypic, tetraploid species, A. glandulosa, appears divided into distinct geographic subgroups, each appearing more genetically similar to other species within each region. Our analyses further suggest that some taxa are of hybrid origin, or are introgressed. We are generating morphological and environmental datasets to complement these genomic data in order to comprehensively assess species boundaries in Arctostaphylos.

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1 - University Of California Riverside, Botany And Plant Sciences, 900 University Ave, Riverside, CA, 92521, United States
2 - 24548 Covington Way, Moreno Valley, CA, 92557, United States
3 - University of California Riverside, Botany and Plant sciences, 900 University Ave, Riverside, California, 92521, United States
4 - University of California, Riverside, 900 University Ave, Riverside, CA, 92521, United States
5 - San Francisco State University, Department Of Biology, 1600 Holloway Avenue, San Francisco, CA, 94132, United States
6 - United States Geological Society, 40298 Junction Dr, Oakhurst, CA, 93644, United States
7 - Plymouth State University, 17 High Street, Plymouth, New Hampshire, 03264
8 - University Of California, Riverside, Botany And Plant Sciences, 900 University Avenue, Riverside, CA, 92521, United States

California Floristic Province
species delimitation

Presentation Type: Oral Paper
Session: SYSTIV, Systematics IV: Eurosids & Basal Asterids
Location: Virtual/Virtual
Date: Wednesday, July 21st, 2021
Time: 4:45 PM(EDT)
Number: SYSTIV008
Abstract ID:873
Candidate for Awards:None

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