Abstract Detail

Ericaceae: Systematics, Ecology and Evolution

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

Testing the utility of morphological traits in delimiting a variable subspecies group, the Arctostaphylos glandulosa complex.

While subspecies have long been understood as a level of biological organization below that of species, the criteria for delimiting subspecies vary depending on the group and taxonomist describing the subspecies. Subspecies can therefore have various biological meanings, including morphotypes, unique genetic subgroups, or suspected incipient species. However, because taxa should have evolutionary relevance, some level of genetic differentiation among subspecies should be requisite to their validity, though taxonomists may disagree on the level of differentiation. Beyond lack of consensus on criteria of delimitation and biological meaning, overlap among subspecies ranges and ongoing gene flow among subspecies present practical challenges, as the differences among subspecies are blurred by intermediate individuals. Recent technological advances, however, in next-generation sequencing, computational methods, and analysis, present new opportunities to revisit historically difficult groups with increased power to sort out subspecific diversity from the perspective of both morphology and genetic variation. Addressing these problem groups improves our understanding of the biological meaning of diversity below the species level and thus informs appropriate conservation decisions. Arctostaphylos glandulosa Eastw., commonly known as Eastwood's manzanita, occurs throughout most of the California Floristic Province and is currently described as a complex of ten subspecies. These are woody shrubs typically found in chaparral, adapted to fire by resprouting from a basal burl. Subspecies are distinguished using a set of trichome, fruit, and leaf morphological characters, though these show much natural variability. Additionally, numerous subspecific taxa are routinely identified in the same population, raising the question of whether the subspecies are morphotypes rather than genetic or evolutionary units. The difficulty of distinguishing these subspecies may have conservation consequences as one subspecies, A. glandulosa subsp. crassifolia, currently has protected status, and another, A. glandulosa subsp. gabrielensis, is listed by California Native Plant Society as endangered. The characteristics of the A. glandulosa subspecies complex that make its taxonomy challenging to understand make it a good system to apply modern methods to test the distinctiveness of a set of subspecies, from a morphological and genetic standpoint. We used a SNP dataset derived from ddRADseq of individuals sampled across southern California to infer population genetic structure, and applied morphometric image analysis to quantify leaf shape, trichome length and density, and stomatal density. We applied principal components analysis and linear discriminant analysis to morphometric datasets to test the morphological distinction of subspecies taxa and test the correlation between morphological variation and genetic population structure.

1 - University Of California Riverside, Botany And Plant Sciences, 900 University Ave, Riverside, CA, 92521, United States
2 - University of California, Riverside, Botany and Plant Science, 900 University Ave, Batchelor Hall, Riverside, California, 92521, USA
3 - 24548 Covington Way, Moreno Valley, CA, 92557, United States
4 - Plymouth State University, Biology, 17 High Street, MSC 48, Plymouth, NH, 03264, USA
5 - 13411 Bean Flat Road, Chico, CA, 95928, United States
6 - San Francisco State University, Biology, 1600 Holloway Avenue, Department Of Biology, San Francisco, CA, 94132, United States
7 - USGS Western Ecological Research Center, Sequoia Kings Canyon Field Station, 47050 Generals Hwy, Three Rivers, CA, 93271, USA
8 - University Of California, Riverside, Botany And Plant Sciences, 900 University Avenue, Riverside, CA, 92521, United States

Keywords:
manzanita
subspecies
RADseq
California Floristic Province
morphology
Morphometrics.

Presentation Type: Colloquium Presentations
Session: C07b, Ericaceae: Systematics, Ecology, and Evolution Part 2
Location: 114/Mayo Civic Center
Date: Tuesday, July 24th, 2018
Time: 4:30 PM
Number: C07b012
Abstract ID:741
Candidate for Awards:None