DOI: 10.5061/dryad.rfj6q57jn
title: Data from: Climatic temperature and precipitation jointly influence body size in species of western rattlesnakes

description: Both the metabolic theory of ecology and dynamic energy budget theory
 predict that climate influences body size through its effects on first
 order determinants of energetics: reactive temperatures, carbon resources,
 and oxygen availability. Although oxygen is seldom limiting in terrestrial
 systems, temperature and resources vary spatially. While controlling for
 effects of spatial autocorrelation, we used redundancy analyses and
 variation partitioning to evaluate the influence of climatic temperature,
 precipitation, and their seasonalities, on multivariate body size across
 the distributions of four species of the western rattlesnake group in
 North America (Crotalus pyrrhus, C. scutulatus, C. oreganus, C. viridis).
 Most species showed a pattern of increased body size in cooler, mesic
 climates, and decreased body size in warmer, xeric climates. Exceptions to
 the pattern provided additional context through climatic idiosyncrasies in
 the distributions of each species. For example, the general pattern of a
 negative influence of temperature on body size was not apparent for C.
 oreganus, which among the four species ranges across the mildest climates
 overall. Moreover, excepting C. oreganus, complimentary multiple
 regression analyses indicated that the negative influence of high
 temperatures on body size was likely stronger than the positive influence
 of greater precipitation. In contrast to previous studies, our results
 found that seasonality had negligible effects on body size. We suggest
 that precipitation gradients correlate positively with resource
 availability in driving intraspecific body size, and that temperature
 compounds this gradient by increasing baseline metabolic demands and
 restricting activity in particularly warm or otherwise extreme climates.
description: The dataset includes species identifiers, geographic coordinates
 of origin for specimens (in decimal degrees), sex, and linear measurements
 for 1531 specimens of four species of rattlesnakes (<em>Crotalus
 pyrrhus</em>, <em>C. scutulatus</em>, <em>C.
 oreganus</em>, and <em>C. viridis</em>). All data are
 raw (i.e., untransformed) and in mm scale. Abbreviated column headings for
 morphometric variables are defined in electronic supplementary
 material.
description: # Climatic temperature and precipitation jointly influence body size in
 species of western rattlesnakes
 [https://doi.org/10.5061/dryad.rfj6q57jn](https://doi.org/10.5061/dryad.rfj6q57jn) The dataset includes species identifiers, geographic coordinates of origin for specimens (in decimal degrees), sex, linear measurements (in mm) for 1531 specimens of four species of rattlesnakes (*Crotalus pyrrhus*, *C. scutulatus*, *C. oreganus*, and *C. viridis*). Climate data corresponding to specimen coordinates can be retrieved from Worldclim ([https://www.worldclim.org/](https://www.worldclim.org/)). This data frame was used in redundancy and multiple regression analyses to evaluate the influence of climatic variables on body size across species. ## Description of the data and file structure Data are provided as a single .csv data frame ("crotalus.csv"). The nine linear measurements are in mm. Abbreviated column headings are defined as follows: Spec.ID: species identifier for the four Crotalus species evaluated: pyrrhus, scutulatus, oreganus, viridis Lat: Latitude in decimal degrees for specimen locality of collection Long: Longitude in decimal degrees for specimen locality of collection Sex: Sex of specimen from anatomical evaluation BL: body length - excludes head length and tail length (i.e., a measure of trunk length) TAIL: tail length - measured from cloaca to base of rattle HDL: head length - measured from rostral plate to the angle of articulation of the quadrate and mandible HDW: head width - measured at widest point SNTL: snout length - measured from anterior edge of eye to the center of the rostral plate EPD: eye-pit distance - measured as shortest distance between anterior edge of eye and posterior edge of pit organ ISD: intersupraocular distance - measured from lateral edges of supraocular scales EYE: eye diameter - measured along midline of eye between anterior and posterior edge BRW: basal rattle width - measured on dorsal-ventral axis of proximal rattle segment ## Sharing/Access information Data were derived from the direct measurement of rattlesnake specimens accessioned at various natural history repositories.