DOI: 10.5061/dryad.j3tx95xh3
title: Scale-dependent environmental effects on phenotypic distributions in Heliconius butterflies

description: Examining how environmental factors influence phenotypic distribution
 might provide valuable information about local adaptation, divergence, and
 speciation. The red-yellow Müllerian mimicry ring of Heliconius
 butterflies displays a wide range of color patterns across the Neotropics
 and is involved in several hybrid zones, making it an excellent system to
 study color phenotypic distribution. Using a multiscale distribution
 strategy, we studied whether different phenotypes of the distantly related
 species H. erato and H. melpomene, belonging to the
 red-yellow mimetic ring, are associated with different environmental
 conditions. We show that environmental gradients (particularly heat and
 precipitation factors) drive Heliconius phenotypic distributions, but that
 phenotype and environmental correlations vary with spatial scale. While
 co-mimics are frequently found in similar environments at a broad scale,
 patterns at the local level are not necessarily consistent (different
 variables are the best predictors of phenotypic occurrence in different
 areas) or congruent (co-mimic pairs show distinct associations with the
 environment). Thus, large-scale analysis may help to identify how
 environmental heterogeneity influences broad mimic phenotypic
 distributions, but local studies are needed to understand the
 context-dependent biotic, abiotic, and historical mechanisms that drive
 finer-scale phenotypic shifts.
description: The large-scale distribution of<em> H. erato </em>and
 <em>H. melpomene</em> phenotypes within the red-yellow
 Müllerian mimicry ring was predicted using Species Distribution Modelling.
 Our data comprised 3,403 occurrence points in total, including samples
 collected from December 2016 to June 2017 and July to October 2018 using
 entomological nets at 25 km intervals over four transects in the Brazilian
 Amazon, totaling 77 locations across 1,905 km. We also included samples
 from the collection of the Laboratory of Ecology and Systematics of
 Pollinators and Predators (LESPP - Federal University of Maranhão) and
 data used in Rosser et al. (2012), available at https://heliconius-maps.github.io/. The variables in our environmental dataset were chosen for their possible direct and indirect effects on <em>Heliconius</em> ecology and evolution. These were prepared using QGIS (QGIS Association 2020) with a 1km resolution. Our local-scale analysis was performed using solely the samples collected within two transects in the Brazilian Amazon crossing two hybrid zones (based on intermediate color phenotypes). To verify if the four previously identified phenotypes constituted different clusters based on color patterns, we ran color variation tests. We used the patternize R package to perform a Principal Component Analysis (PCA) on high-resolution images of <em>H. erato</em> and<em> H. melpomene </em>races that represented the four phenotypes of the red-yellow mimetic ring (Van Belleghem et al. 2018). We then calculated the wing surface area containing black in the different clusters using one-way ANOVA and Tukey testing to analyze differences in black patterning among phenotypes. Lastly, we used the bahz R package to do cline analysis using a Bayesian method (Thurman, 2019).
description: For more information, check MARTINS_2022_README.txt