DOI: 10.5061/dryad.6hdr7sr6h
title: Supplemental data for: Parallel shifts in flight-height associated with altitude across incipient Heliconius species

description: Vertical gradients in microclimate, resource availability and
 interspecific interactions are thought to underly stratification patterns
 in tropical insect communities. However, only a few studies have explored
 the adaptive significance of vertical space use during the early stages of
 reproductive isolation. We analysed flight-height variation across
 speciation events in Heliconius butterflies representing parallel
 colonisations of high-altitude forest. We measured flight-height in wild
 H. erato venus and H. chestertonii, parapatric lowland and mountain
 specialists respectively, and found that H. chestertonii consistently
 flies at a lower height. By comparing our data to previously published
 results for the ecologically equivalent H. e. cyrbia (lowland) and H.
 himera (high-altitude), we found that the species flying closest to the
 ground are those that recently colonised high-altitude forests. We show
 that these repeated trends largely result from shared patterns of
 ecological selection producing parallel trait-shifts in H. himera and H.
 chestertonii. Although our results imply a signature of local adaptation,
 we did not find an association between resource distribution and
 flight-height in H. e. venus and H. chestertonii. We discuss how this
 pattern may be explained by variation in forest structure and
 microclimate. Overall, our findings underscore the importance of
 behavioural adjustments during early divergence mediated by
 altitude-shifts.
description: We characterised the local
 forest structure by measuring the trunk diameter at breast height (m) and
 the average distance (m) between neighbouring trees of common tree species
 along 15–20m sections of the trails used for collecting butterflies.
 For the tallest trees, we
 measured the angle of elevation to the treetop with a clinometer. The
 tangent of this angle was then multiplied by the distance to the tree from
 the point of observation to estimate height. Shorter trees were measured
 using measuring tapes. We measured the height (m) of all the
 <em>Passiflora</em> (Passifloraceae) hostplants that were
 visually identified along the trails used to collect butterflies. We also
 measured the height (m) of the flowering plants that butterflies were
 observed feeding from at least once. 
 In our study, flight-height is
 defined as the length of the line perpendicular to the ground level from
 the point where individuals were first observed, as estimated with a
 measuring tape. Each measured individual (<em>H. e. venus
 </em>n=33 and <em>H. chestertonii</em> n=39) was stored,
 ensuring no repeated observations. 
description: # Supplemental data for: Parallel shifts in flight-height associated with
 altitude across incipient Heliconius species ## Description of the Data
 and file structure This data set consists of CSV tables with raw data for
 the manuscript by the title and a .Rmd file with the annotated scripts
 used in the analyses. The tables are labeled S1-S4. S1 includes the
 taxonomic identity of plant species (hosts or flowering plants) used by
 butterflies in the study and their heights (meters). S2 contains forest
 density data measured as "Diameter at the breast height" (DBH),
 "Average distance between neighbouring trees" (ADNT, in meters)
 for trees measured at dry-high-altitude (DHA, in meters) or
 wet-low-altitude (WLA, in meters) S3 contains forest vertical structure
 data measured as height of trees measured at the canopy, undercanopy or
 scrub at dry-high-altitude (DHA, in meters) or wet-low-altitude (WLA, in
 meters) S4 contains flight-height (meters) data for butterflies of the
 four species considered in the study. ## Sharing/Access information For
 this study, the authors used publicly available data derived from
 "Dalbosco Dell'Aglio, Denise et al. (2022). Divergence in
 Heliconius flight behaviour is associated with local adaptation to
 different forest structures [Dataset]": Dryad.
 [https://doi.org/10.5061/dryad.msbcc2fx8]