DOI: 10.5061/dryad.280gb5n10
title: Data from: Testing prerequisites to adaptation in Quercus agrifolia: Are leaf domatia a heritable trait?

description: On Quercus agrifolia Née, Fagaceae, (Coast Live Oak) trees in California,
 small clusters of branched trichomes on the abaxial leaf surface serve as
 domatia, protective structures for mites. These structures are a
 distinguishing characteristic of Q. agrifolia and we hypothesize may be
 shaped by natural selection. Here we test the first two of three
 prerequisites for adaptation via natural selection: (1) the trait must
 vary among individuals, and (2) the trait must be heritable. Trait
 variance across 20 trees in a natural stand was assessed by collecting 20
 leaves per tree and determining the proportion of leaf vein axils with
 domatia. From the same trees, acorns were collected, germinated, and the
 proportion of leaf vein axils with domatia was recorded for 12- and
 18-month-old saplings. Heritability was then assessed by comparing the
 resemblance between maternal trees and offspring. We find that both
 prerequisites are met: maternal trees exhibit substantial variation in the
 proportion of leaf vein axils with domatia, ranging from an average of
 0–0.85 per leaf, and heritability estimates for 12- and 18-month-old
 saplings were 0.33 ± 0.10SD and 0.53 ± 0.10SD respectively. A follow up
 study is needed to assess the third prerequisite for adaptation via
 natural selection, that survival and reproduction of oaks varies based on
 the proportion of leaf vein axils with domatia. We hope future researchers
 will pursue this line of study.
description: # Testing prerequisites to adaptation in Quercus agrifolia: Are leaf
 domatia a heritable trait?
 [https://doi.org/10.5061/dryad.280gb5n10](https://doi.org/10.5061/dryad.280gb5n10) ## Description of the data and file structure This study took place in a natural stand of Quercus agrifolia in “Poly Canyon” at California Polytechnic University, San Luis Obispo, California. To test whether there is variance among individuals in the proportion of leaf vein axils with domatia, 20 trees were sampled in fall of 2022. From each of these trees, 20 leaves were selected for inspection, each from a separate branch within the sub-canopy. Each leaf was examined under a dissecting microscope and the total number of leaf vein axils and the total number of domatia was recorded. To test whether domatia are a heritable trait, 20 acorns were collected from each maternal tree described above. Acorns were planted into trays to germinate in a closed greenhouse in October 2022 without artificial light and with daily temperatures ranging from about 10–24° C. All germination occurred within 2–4 weeks. Once established, seedlings were transplanted to gallon sized pots and moved to an open-air greenhouse for the remainder of the study, without artificial light and with daily temperatures ranging from about 10–35° C. Phenotyping of the sapling offspring occurred twice, once at ~12 months old (October, 2023) and again at ~18 months old (April, 2024) to determine whether age of sapling impacted our assessment of heritability. For phenotyping, we sampled three leaves per sapling per timepoint by selecting fully expanded leaves from the lower, middle and highest portion of each sapling. The method for leaf phenotyping of the offspring was the same as for the maternal trees described above and we recorded the number of total leaf vein axils and the number of axils with domatia for each leaf. ### Files and variables #### File: Data\_Ormiston\_etal\_2025.csv **Description:** Data of all leaves sampled for maternal trees and their offspring. Each row represents one leaf. ##### Variables * Cohort: either "mom" or "offspring" generation * SampleDate: indicated as year_month * MaternalTreeID: numeric value between 1 and 20 indicating the identification of the maternal tree * SaplingID: Letter indicating the identification of the sapling (offspring) from a given maternal tree. Note that cells contain "NA" for cohort "mom" where this does not apply.  * SaplingLeafLocation: Location where each leaf was sampled within a sapling (a = lower, b = middle and c = highest portion of each sapling). Note that cells contain "NA" for cohort "mom" where this does not apply.  * AxilNum: Total count of leaf vein axils per leaf. Note that cells contain "NA" when there were missing values. * DomatiaCount: Total count of domatia per leaf. Note that cells contain "NA" when there were missing values. * Latitude: Latitude in degrees, minutes, seconds for location of maternal tree. Note that cells contain "NA" for cohort "offspring" where this does not apply.  * Longitude: Longitude in degrees, minutes, seconds for location of maternal tree. Note that cells contain "NA" for cohort "offspring" where this does not apply.  * Notes: Any notes made during observation. Note that cells contain "NA" when there were no notes made. ## Code/software Code for all analyses, traceplots, and figure 2.