DOI: 10.5061/dryad.qrfj6q5st
title: Data from: Temporal trends in allometry of shell calcification in northeastern Pacific venerid bivalves: Implications for predicting responses to climate change

description: Despite a literature spanning almost a century, how allometric
 relationships of phenotypic traits behave over evolutionary time still
 remains poorly known for most marine species. In particular, the fossil
 record is seriously underutilized in this context despite harboring a rich
 archive of traits. Here we use the late Pleistocene fossil record in San
 Diego, California, in conjunction with archival and field-collected
 specimens, to quantify temporal changes in allometric relationships
 between shell size and calcification, two important functional traits, in
 five different species of marine bivalves. Our results reject the
 traditional hypothesis that allometric relationships are statistically
 invariant over time. They also show that temporal changes in allometric
 relationships are species-specific, with closely related species showing
 divergent trends. Finally, we argue that information about the nature of
 long-term changes in allometric relationships of functionally important
 traits can provide an important yet underappreciated tool for
 understanding species and population responses to climate change.
description: # Data from: Temporal trends in allometry of shell calcification in
 northeastern Pacific venerid bivalves: Implications for predicting
 responses to climate change Dataset DOI:
 [10.5061/dryad.qrfj6q5st](10.5061/dryad.qrfj6q5st) ## Description of the
 data and file structure This datafile contains measurements of shell size
 and thickness for late Pleistocene and Holocene specimens of multiple
 species of Venerid bivalves from San Diego, California, USA. The data
 include specimens from archival collections as well as field-collected
 Holocene specimens. ### Files and variables #### File: Bullard_Roy_code.R
 **Description:** R code for the analyses in Bullard and Roy 2025. The code
 is commented. #### File: Bullard_Roy_Data.csv **Description:**  #####
 Variables * Family: Currently accepted familial designation for each
 specimen. * Genus: Currently accepted genus designation for each specimen.
 * species: Currently accepted species designation for each specimen. *
 Time: The term Pleistocene refers to all of the fossil specimens used.
 Holocene includes both historical and field collected living specimens.
 Please see Bullard and Roy 2025 for further details about each category. *
 Locality: Site of collection. * Note that the spatial resolution of museum
 material is variable. The data includes the highest spatial resolution
 available for each specimen. * County: All of the data are from San Diego
 County, California, USA. * Source: The institution where the material is
 archived. * SBMNH = Santa Barbara Museum of Natural History. * LACM =
 Natural History Museum of Los Angeles County. * UCSD = University of
 California San Diego. * SDMNH = San Diego Natural History Museum. *
 Museum.ID: Specimen id for museum specimens derived from the museum
 labels. * Field collected specimens do not have a museum id so are
 represented as n/a. * Year.Collected: The year specimen was collected. *
 Note that this information is not available for some museum specimens.
 Those are designated by n/a. * Height.mm: Height of each shell measured in
 mm. Please see Bullard and Roy 2025 for details. * Length.mm: Length of
 each shell measured in mm. Please see Bullard and Roy 2025 for details. *
 Thickness.1: The first thickness measure of each shell in mm. Please see
 Bullard and Roy 2025 for details about how thickness was measured.  *
 Thickness.2: The second thickness measure of each shell in mm. Please see
 Bullard and Roy 2025 for details about how thickness was measured. * n/a
 represents cases where it was not possible to measure this variable. *
 Thickness.3: The third thickness measure of each shell in mm. Please see
 Bullard and Roy 2025 for details about how thickness was measured. * n/a
 represents cases where it was not possible to measure this variable. *
 Thickness.4: The fourth thickness measure of each shell in mm. Please see
 Bullard and Roy 2025 for details about how thickness was measured. * n/a
 represents cases where it was not possible to measure this variable. *
 Thickness.5: The fifth thickness measure of each shell in mm. Please see
 Bullard and Roy 2025 for details about how thickness was measured. * n/a
 represents cases where it was not possible to measure this variable. *
 Thickness.6: The sixth thickness measure of each shell in mm. Please see
 Bullard and Roy 2025 for details about how thickness was measured. * n/a
 represents cases where it was not possible to measure this variable. *
 Thickness.7: The seventh thickness measure of each shell in mm. Please see
 Bullard and Roy 2025 for details about how thickness was measured. * n/a
 represents cases where it was not possible to measure this variable. *
 size: defined as geometric mean of length and height. See Bullard and Roy
 2025 for details. * mean_thickness: Average thickness of each specimen in
 mm. ## Code/software The data are in the CSV format and can be viewed with
 any spreadsheet or text editor capable of opening CSV files. The code was
 written in R version 4.3.1. The code is commented.