DOI: 10.5061/dryad.c2fqz61cp
title: Environment rather than character displacement explains call evolution in glassfrogs

description: The Acoustic Adaptation Hypothesis (AAH) and Ecological Character
 Displacement (ECD) are two potential mechanisms shaping call evolution
 that can predict opposite trends for the differentiation of signals. Under
 AAH, signals evolve to minimize environmental degradation and maximize
 detection against background noise, predicting call homogenization in
 similar habitats due to environmental constraints on signals. In contrast,
 ECD predicts greater differences in call traits of closely-related taxa in
 sympatry because of selection against acoustic interference. We used
 comparative phylogenetic analyses to test the strength of these two
 selective mechanisms on the evolution of advertisement calls in
 glassfrogs, a highly diverse family of neotropical anurans. We found that,
 overall, acoustic adaptation to the environment may outweigh effects of
 species interactions. As expected under the AAH, temporal call parameters
 are correlated with vegetation density, but spectral call parameters had
 an unexpected inverse correlation with vegetation density, as well as an
 unexpected correlation with temperature. We detected call convergence
 among co-occurring species and also across multiple populations from the
 same species in different glassfrogs communities. Our results indicate
 that call convergence is common in glassfrogs, likely due to habitat
 filtering, while character displacement is relatively rare, suggesting
 that costs of signal similarity among related species may not drive
 divergent selection in all systems.
description: We gathered all available glassfrog calls from sound collections,
 and we supplemented the data set with contributions from colleagues, call
 descriptions available in literature, and our own recordings obtained in
 the field. For each species, we obtained two spectral and four temporal
 call parameters: peak frequency (frequency at which the highest amplitude
 peak is found, also known as dominant frequency), frequency bandwidth (the
 difference between upper and lower frequency bounds of notes, as measured
 6 dB below the peak frequency), note duration (length in milliseconds of a
 note, measured from beginning to end of the note), notes per call, pulse
 rate (number of pulses in a note minus 1, divided by the length of the
 note; with this formula, purely tonal calls always have a pulse rate of
 zero) and note rate (count of notes in a call minus 1, divided by the
 length of the call). <br><br>We obtained georeferenced records
 to infer the distribution for all glassfrog species included in this study
 from the database generated by Hutter et al. (2013), which was modified
 with updated species names and supplemented with recent data. For each
 record, we extracted the environmental temperature, estimated from the
 mean temperature of the wettest quarter (CHELSA BIO8, Karger and
 Zimmermann 2019) as a proxy for the temperature during the rainy season,
 when glassfrog reproductive activity peaks. For <em>H. fleischmanni
 </em>lineages, we used the available air temperature registered in
 the metadata of the recording event. We also extracted vegetation density,
 taken from the Enhanced Vegetation Index (EVI) proposed by the MODIS Land
 Discipline Group (Liu and Huete 1995) and derived from aerial assessments
 of forest canopy for both datasets, for this, we obtained the mean value
 per cell for 204 layers with monthly data between 2000 and 2017.
description: # Environment rather than character displacement explains call evolution
 in glassfrogs --- **Authors**: Angela M. Mendoza-Henao, Kelly R. Zamudio,
 Juan M. Guayasamin, Moises Escalona, Gabriela Parra-Olea ## Dataset
 Details ### **DryadEvolution.zip** This archive contains three files, each
 described below: #### 1. **Callmetrics.csv** **Description**: Acoustic and
 environmental variables for glassfrog species. **Variables**: *
 **Species**: Scientific name of each species, in the format Genus_species.
 * **SVL**: Snout-Vent Length (mm; body size measurement). * **PeakFreq**:
 Peak call frequency (Hz). * **Bandwidth**: Frequency range of call notes
 (Hz; measured 6 dB below peak frequency). * **MaxNotes**: Maximum number
 of notes per call. * **SyllDur**: Syllable duration (ms). * **noterate**:
 Call rate (notes per second; calculated as `(notes - 1) / call duration`).
 * **pulserate**: Pulse rate (pulses per second; purely tonal calls = 0). *
 **EVI**: Enhanced Vegetation Index (MODIS Land Discipline Group). *
 **Temperature**: Mean temperature of wettest quarter (Bio8; °C). *
 **Prec**: Mean precipitation (mm). * **PC1Temp**: Principal Component 1
 summarizing temporal climatic variables. * **ResidSVL**: Residuals from
 SVL vs. Peak Frequency regression. * **Genus**: Taxonomic genus. *
 **Pulses**: Number of pulses per call. * **Subfamily/Genus/Clade
 columns**: Binary indicators (0/1) for taxonomic subsets (e.g.,
 `Centroleninae`, `Hyalinobatrachium`, `Hyalino17sp`). **Missing Data
 (`NA`)**: * `NA` indicates **non-available data**, either due to
 unmeasured variables (e.g., missing acoustic measurements) or absence of
 applicable values (e.g., pulse rate for non-pulsed calls). --- #### 2.
 **FrogsTree.tre** **Description**: Time-calibrated phylogenetic
 ultrametric tree (Nexus format) for 100 glassfrog species with molecular
 and acoustic data. **Details**: * The name of each coincides with those on
 the Species column in the "Callmetrics.csv" file * Used for
 comparative analyses in the study. * Some branches were pruned in specific
 analyses (noted in the manuscript). --- #### 3.
 **SpeciesxSitesMatrix.csv** **Description**: Presence-absence matrix of
 glassfrog species (columns) across their geographic ranges (rows).
 **Details**: * **Values**: `1` = presence, `0` = absence. * **Purpose**:
 Measures species co-occurrence for community-level analyses. * **Missing
 Data (`NA`)**: Not applicable (all cells are populated with 0 or 1). ---
 ### **CallEvolAnalysis.R** **Description**: R script reproducing all
 analyses and figures from the manuscript. **Usage**: * Requires the three
 files above (`Callmetrics.csv`, `FrogsTree.tre`,
 `SpeciesxSitesMatrix.csv`). * No external files needed; self-contained. *
 Refer to manuscript for analysis context. --- ## Sharing/Access
 Information Datasets are part of the study published by Mendoza-Henao et
 al. (Evolution). **Related Publication**: Mendoza-Henao, A. M., Zamudio,
 K. R., Guayasamin, J. M., Escalona, M., & Parra-Olea, G. (2023).
 Environment rather than character displacement explains call evolution in
 glassfrogs. Evolution, 77(2), 355-369.