DOI: 10.5061/dryad.nzs7h452t
title: Unapparent trees: escaping enemies in time by being discreet, unpredictable and inaccessible

description: For half a century, biologists considered trees as particularly apparent
 to their enemies. But why then do some trees escape herbivorous enemies by
 bursting buds either too early or too late, leading to phenological
 mismatch? We hypothesize that such mismatches occur on trees that are
 unapparent in time—those that burst buds “discreetly” (slowly) and
 unpredictably (inconsistently across years), and are difficult to access
 (host trees among non-hosts). We studied herbivores on oaks in Western
 France. We for the first-time characterized phenology matching of an
 entire guild of herbivores, early spring ectophagous caterpillars (45
 species). We examined whether, on a given date, caterpillars have a large
 body size and impact (herbivory), and whether this size or impact is
 largest on trees that burst buds earliest. Furthermore, we distinguished
 the contributions of within-guild sorting of species and within-population
 selection of individuals to phenology matching, we investigated whether
 present phenology matching was determined during past generations by
 testing if caterpillars from trees with early-maturing foliage pupate
 early, even when transferred into a common garden. We found that
 caterpillar size and herbivory impact in the field and pupation date in
 the lab generally matched leaf phenology in the field. Such phenology
 matching was consistently observed at the intraspecific level but was less
 evident at the interspecific level. Together this indicates that phenology
 matching is mainly driven by past within-population selection rather than
 present, within-guild sorting. Furthermore, herbivores size and impact
 were most constrained by late bursting of host trees if these trees burst
 buds slowly and unpredictably and are difficult to access. We suggest
 that, during the assembly of early-spring herbivore guilds, trees can best
 constrain development of herbivore populations by late budburst and
 remaining unapparent in time—bursting buds discreetly, unpredictably
 across years, or in inaccessible neighbourhoods.
description: # Unapparent trees: escaping enemies in time by being discreet,
 unpredictable and inaccessible Dataset DOI:
 [10.5061/dryad.nzs7h452t](10.5061/dryad.nzs7h452t) ## Description of the
 data and file structure The data are also given in the Supplementary
 document, and are described there. ### Files and variables #### File:
 Caterpillar-Data-Unapparent-trees.csv **Description:** This file contains
 data on caterpillars, including their length measured within two days of
 field collection. It also includes characteristics of the host trees from
 which the caterpillars were collected, such as budburst timing, budburst
 speed, within-crown heterogeneity of budburst, and phylogenetic and
 spatial distances from neighbouring trees. Entries marked as
 "NA" indicate that data were not available for those specific
 cases. ##### Variables * Row.number: Unique row number * Year: Year of
 sampling i.e. 2010 or 2011 or 2019 * Tree: Unique identification number of
 the trees * Budburst.DOY: Day of the year when a tree reached its
 mid-point of budburst * Mean.budbusrt: Mean of Budburst.DOY of all the
 trees in a given year * Relative.budburst: In a given year, the difference
 (in days) between a tree’s budburst date (Budburst.DOY) and the mean
 budburst date all the trees (Mean.budburst). * Budburst.speed: The rate at
 which a tree completes budburst, measured as the average daily increase in
 budburst score from the onset of budburst until completion (see Methods
 for details). The unit is budburst score per day. *
 Budburst.heterogeneity: The standard deviation of budburst scores measured
 across 20 individual buds on a single tree. * Budburst.consistency: The
 consistency of a tree’s budburst timing across years, reflecting whether
 it consistently buds earlier or later relative to others, or shows
 variability (e.g., early in one year but average in another). This was
 quantified as the standard deviation of the tree’s Relative.budburst
 values across years (see Methods for details). * Phy.Iso: Phylogenetic
 isolation of a tree, defined as the average phylogenetic distance (in
 millions of years) between the focal tree and all neighboring trees with
 which it shares direct crown contact (see Supplementary Material for
 details) * Dist2Oak: The spatial distance (in meters) from the focal oak
 tree to its nearest conspecific neighbor. * Leaf.advancement: A measure of
 leaf maturation in mid-June, indicating the development level of defensive
 chemicals (e.g., flavonols, anthocyanins) and physical traits (e.g.,
 toughness, thickness) at this stage (see Methods for details). As a
 relative measure, this variable is unitless. * Caterpillar.abundance:
 Number of caterpillar present per leaf of a tree in a given year *
 Herbivory.rate: Proportion of leaf area consumed by ectophagous
 caterpillars * Caterpillar.ID: Unique identification number of each
 caterpillar in a given year * Caterpillar.size(mm): Length of caterpillars
 in milimeters (measured within two days after collection from the field) *
 Caterpillar.species: Species identity of each caterpillars *
 Caterpillar.species.mean.timing: The average relative budburst timing (in
 days) of all host trees used by caterpillars of a specific species within
 a given year (see Methods for details).  *
 Within.caterpillar.species.timing: For an individual caterpillar in a
 given year, the deviation (in days) of its host tree’s budburst timing
 from the species-specific mean budburst timing (i.e.,
 Caterpillar.species.mean.timing; see Methods for details). #### File:
 Pupaation-data-Unapparent-trees.csv **Description:** This file contains
 data on the timing of pupation, specifically the day in 2019 when
 caterpillars collected from the field pupated under laboratory conditions.
 It also includes characteristics of the host trees from which the
 caterpillars were collected, such as leaf development stage, budburst
 timing, budburst speed, within-crown budburst heterogeneity, and
 phylogenetic and spatial distances to neighboring trees. Entries marked as
 "NA" indicate that data were not available for those specific
 cases. ##### Variables * Cat ID: Unique identification number of each
 caterpillar in 2019 * Tree: Unique identification number of the trees *
 Pupation Date: Date when the caterpillar pupated (format DD/MM/YYYY) *
 Pupation DOY: Day of year when the caterpillar pupated * Leaf
 advancement: A measure of leaf maturation in mid-June, indicating the
 development level of defensive chemicals (e.g., flavonols, anthocyanins)
 and physical traits (e.g., toughness, thickness) at this stage (see
 Methods for details). As a relative measure, this variable is unitless. *
 Caterpillar.species: Species identity of each caterpillars *
 Caterpillar.species.mean.leaf.advancement: The average 'Leaf
 advancement' of all host trees utilized by caterpillars of a
 particular species (see Methods for details). As a relative measure, this
 variable is unitless. * Within.caterpillar.species.leaf.advancement: For a
 given caterpillar, the deviation of its host tree’s 'Leaf
 advancement' from the species-specific mean (i.e.
 Caterpillar.species.mean.leaf.advancement, see Methods for details). As a
 relative measure, this variable is unitless. * Budburst.speed: The rate at
 which a tree completes budburst, measured as the average daily increase in
 budburst score from the onset of budburst until completion (see Methods
 for details). The unit is budburst score per day. *
 Budburst.consistency: The consistency of a tree’s budburst timing across
 years, reflecting whether it consistently buds earlier or later relative
 to others, or shows variability (e.g., early in one year but average in
 another). This was quantified as the standard deviation of the tree’s
 Relative.budburst values across years (see Methods for details). *
 Phylogenetic isolation of a tree, defined as the average phylogenetic
 distance (in millions of years) between the focal tree and all neighboring
 trees with which it shares direct crown contact (see Supplementary
 Material for details) * Dist2Oak: The spatial distance (in meters) from
 the focal oak tree to its nearest conspecific neighbor. #### File:
 R-code-Unapparent-trees.R **Description:** This R script was used to
 analyze both attached datasets: caterpillar length and pupation timing.
 The analyses are summarized at the end of the Methods section and are
 documented within the script itself. All analyses were conducted using R
 version 4.4.1. ## Code/software The data are in .csv format, which can be
 opened on Excel The code is in .R format, which can be opened in RStudio
 ## Access information Other publicly accessible locations of the data: *
 The supplementary document of the corresponding publication Data was
 derived from the following sources: * Fieldwork and lab observations