DOI: 10.5061/dryad.6q573n66g
title: Data from: Island biogeography and competition drive rapid venom complexity evolution across rattlesnakes

description: Understanding how human-mediated environmental change affects biodiversity
 and the timescale of an evolutionary response is key for conserving
 evolvability. Islands are proxies for fragmented landscapes and allow us
 to use historical changes in biodiversity under Island Biogeography Theory
 (IBT) to predict the consequences of immediate anthropogenic impacts on
 trait evolution. Rattlesnake venoms are molecular phenotypes that mediate
 interactions with prey, and diet and venom complexity are positively
 correlated. Consequently, rattlesnake venoms allow us to investigate how
 functional traits co-vary with changes in biodiversity according to IBT.
 We collected venom from 83 rattlesnakes across multiple species and 11
 islands in the Gulf of California and estimated venom complexity using the
 Shannon Diversity Index. Using a mixed effects modeling approach, we found
 that the number of congeneric competitors, island isolation, and island
 area best predicted variation in venom complexity. All variables exhibited
 a negative relationship with venom complexity, contrary to predictions for
 island area under IBT. Larger islands with more congeneric competitors
 exhibited reduced trait complexity, likely reflecting niche partitioning
 and venom specialization driven by interspecific competition and/or
 increases in habitat heterogeneity. Ultimately, we used a synthetic
 eco-evolutionary framework to predict functional trait evolution across
 fragmented and isolated habitats.
description: **Files and Descriptions** 1. **Spatial_Modeling_SRH_MAB_Unscaled.rmd** *
 This script performs mixed-effects modeling using unscaled Shannon_H
 values to analyze venom complexity. The model incorporates spatial and
 ecological variables to assess their effects on venom complexity without
 scaling the Shannon_H metric. * Note, geographic coordinates (latitude and
 longitude) of are not included in the dataset used in this analysis;
 therefore, models using spacial autocorrelation will not function. See
 note for the dataset for more information.  2.
 **Spatial_Modeling_SRH_MAB_Scaled.rmd** * This script performs the same
 mixed-effects modeling as the unscaled version but uses scaled Shannon_H
 values for venom complexity. * Note, geographic coordinates (latitude and
 longitude) of are not included in the dataset used in this analysis;
 therefore, models using spacial autocorrelation will not function. See
 note for the dataset for more information.  3. **fig3_script.R** * This
 script generates Figure 3 for the study. It includes the necessary data
 processing, data simulation, visualization steps, and formatting for
 publication-quality output. 4. **RDA.R** * This script conducts a
 conditional redundancy analysis (RDA) on the binned HPLC peak data. The
 analysis evaluates how much variance in venom complexity is explained by
 specific predictor variables while accounting for covariates. 5.
 **Supplemental_Datasets**_**S1.csv** * Note: Geographic coordinates
 (latitude and longitude) of sample collection sites are not included in
 this dataset to protect the sensitive habitats and populations of
 island-dwelling rattlesnake species. Many of these islands are
 ecologically fragile and host endemic or vulnerable taxa. To prevent
 disturbance, unauthorized collecting, or potential exploitation, we have
 withheld precise location data in accordance with best practices for
 conservation-focused research. Researchers with legitimate scientific
 inquiries or conservation interests may request access to the location
 data by contacting the corresponding author. * This csv dataset contains
 all metadata necessary to perform the analyses presented in this study. 6.
 **Binned_peaks_for**_**RDA.csv** * This csv dataset contains binned HPLC
 peak abundance data for all snakes and is necesarry for the RDA conducted
 in the study. For both datasets, column names are as follow: * Tissue_ID -
 ID from researcher's dataset used to distinguish specimens - Species
 - Scientific species name for each specimen. Genus of all species is*
 Crotalus * * Island - Name of the island where specimen was collected -
 Area - Island area (Km^2) * Distance - Island distance from nearest
 mainland (Km) - Age - Estimated age of island (MYA) based on gelogical
 epoch when formed * Rcomp - Number of other rattlesnake species found on
 the island where specimen was collected - Osnake- Number of all other
 snake species found on the island where specimen was collected * Scomp -
 Number of other potential competitor snake species (based on vertebrate
 diet) found on the island where specimen was collected - SVL_cm -
 Snout-vent-length (cm) * Shannon_H - Unscaled venom complexity metric
 calculated from HPLC peak data - Shannon_H_stand - Scaled venom complexity
 metric constrained from 0-1 for each species based on min and max
 Shannon_H values for each species * Peak1 - PeakX- Relative abundance of
 each RP-HPLC peak estimated as area under the peak relative to all other
 peaks - Bin1 - BinX - Relative abundance of each RP-HPLC peak estimated as
 area under the peak relative to all other peaks. Peaks are binned
 according to retention time for consistency among all species