Data from: Temporal trends in allometry of shell calcification in northeastern Pacific venerid bivalves: Implications for predicting responses to climate change
Data files
Jul 17, 2025 version files 187.09 KB
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Bullard_Roy_code.R
3.88 KB
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Bullard_Roy_Data.csv
179.18 KB
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README.md
4.04 KB
Abstract
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.
Dataset DOI: 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.