Morphometric Study of Widespread Arctostaphylos Species Shows Species and Population Variability
Discipline: Ecology Environmental and Earth Sciences
Subcategory: Plant Research
Session: 3
Room: Exhibit Hall
Makayla Drew - Virginia State University
Co-Author(s): Glen Morrison, University of California Riverside, Riverside, CA; Tito Abbo, University of California Riverside, Riverside, CA; Amy Litt, University of California Riverside, Riverside, CA.
As climate change concerns grow stronger, and native plant populations begin to lose their habitats, many scientists and institutions are pushing for increased attention to conserving biodiversity. However, to know the best methods of conservation, attention must first be paid to understanding the factors that drive biodiversity, like geographic isolation between populations.Biodiversity can be measured using both morphometric data and genetic data. In some cases, morphometric data may not be able to distinguish differences at the population level. While a large amount of morphometric data is available from herbarium collections, genetic data can be limited or challenging to obtain for some groups, such as Arctostaphylos. Because of this, morphometric studies can be very useful for quantifying variation seen at species and population levels. The genus Arctostaphylos is the most species diverse woody genus in Western North America. Of the 60 species in this genus, 5 are widespread and should exhibit a high amount of biodiversity. Of the 5 species, we studied populations of Arctostaphylos pungens, A. patula, and A. pringlei, which served as a great model system in which both morphological and genetic distinctiveness could be studied. We hypothesized that sympatric species should be morphologically distinct, but geographically isolated populations of the same species would not appear to be distinct because they still share similar traits due to current gene flow between populations. We tested this hypothesis using a morphometric approach, using herbarium specimens for A. patula, A. pringlei, A. pungens collected from 3 different populations between 2017 and 2022 (n=5). For each specimen, 30 vegetative characteristics were measured. Morphometric data were analyzed using Principal Component Analysis and Linear Discriminant Analysis to quantify variation between species and populations in relation to the traits measured. We saw variation at both the species and population level, when differentiation was only expected to be seen at the species level. The three species were also determined to be very distinct through Principal Component Analysis, with traits such as midrib length and leaf auricularity driving this distinctness. A. pungens had the shortest midrib length (27.7 mm), while A. patula and A. pringlei had longer midrib lengths (32.5 mm and 34.1 mm respectively). Short-read genome sequencing (DDRadSeq) efforts are currently being performed on the same three populations of each species to corroborate the morphological variation and determine genetic differences linked to the variation seen at the species and population level. Comparing the genomic data and morphometric data will provide insight into potential indications of speciation that can be useful in conservation methods related to protection of biodiversity.
Funder Acknowledgement(s): UC Mexus Project, University of California Office of the President.
Faculty Advisor: Sarah Melissa Witiak, switiak@vsu.edu
Role: I measured the herbarium specimens and translated any non-numerical data into a binary format so that it could be used in R studio to generate figures. I also participated in some sample collections relevant to the genomic and morphological studies.