Abstract Detail


Wu, Yingtong [1], Hipp, Andrew [2], Fargo, Gregory [1], Stith, Nora [1], Ricklefs, Robert [1].

Integrating Field, Herbarium, and Ex Situ Samples to Understand the Nature of an Endemic Species, the Maple-leaf Oak.

In the crisis of biodiversity loss, effective conservation of rare species must start with accurate species delimitation. However, species delimitation is challenging in outcrossing species with high plasticity. This challenge can be compounded by collection biases, which may either upweight or downweight specimens that are morphologically intermediate to traditional species. While molecular data are commonly used to solve these problems, only morphometric approaches can connect phenotypic variation to species concepts and link species limits to identification resources used in conservation. We studied the species boundaries of a regional endemic tree, Quercus acerifolia (Maple-leaf Oak), using morphometric analyses of leaf and acorn samples from 527 field and 138 herbarium samples of Q. acerifolia and its close relatives, Q. shumardii and Q. rubra. Despite the well-known rarity of Maple-leaf Oak, some suspected that it is merely a morphotype of Q. shumardii, which is induced by the dry and rocky conditions at mountain ridges. Additionally, its morphological distinctiveness might be over-estimated by collector biases. To address these issues, we employed two novel approaches: sampling ex situ Q. acerifolia to tease apart plastic from genetic sources of phenotypic variation, and comparing randomly sampled material to herbarium sampled material to test for collector biases. Using field and ex situ samples, we identified Q. acerifolia with genetically determined morphological and ecological traits distinctive from co-occurring close relatives Q. shumardii and Q. rubra, supporting its species status. We found high mismatch between phenotypic clusters and current taxonomy, which compromises conservation efforts of this endemic species. We also detected a collection bias towards larger morphological gaps among species in historical herbarium samples. Our study demonstrates how integrating field, herbarium, and ex situ samples can isolate the effects of plasticity and sampling biases, bolstering our confidence in morphologically-based species delimitation. We advocate for the importance of adjusting and re-tuning species definitions at the outset of rare species conservation.

1 - University of Missouri, St. Louis, Biology Department, 1 University Blvd., St. Louis, MO, 63110, USA
2 - The Morton Arboretum, 4100 Illinois Route 53, Lisle, IL, 60532, United States

rare plants
species conservation
species delimitation
morphological species delimitation
Quercus species
ex situ living collections.

Presentation Type: Oral Paper
Number: SYST II004
Abstract ID:144
Candidate for Awards:None

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