DOI: 10.5061/dryad.fqz612k61
title: Ecological and paleontological implications of trematode-induced morphospace inflation and pallial sinus reduction in bivalve hosts

description: Digenean trematodes are parasites with a complex life cycle that often
 infest shell-bearing mollusks and produce distinct traces on the host
 skeleton that are recognizable in the fossil record. Here, three bivalve
 species (Transennella conradina, Abra segmentum, and Chamelea gallina)
 from Pleistocene and Holocene deposits of Florida and Italy were used to
 evaluate the hypothesis that trematode infestation affects shell
 morphology. The morphological effects of infestation were evaluated using
 geometric morphometrics and the Pallial Sinus Index (PSI = Pallial Sinus
 Length / Shell Length). For all three host species: (1) large size classes
 possess higher trematode prevalence (i.e., proportion of specimens
 possessing trematode-induced pits within a population) and higher
 per-specimen frequency of trematode-induced scars when compared to smaller
 size classes, suggesting ontogenetic accumulation of parasites; (2)
 infested and non-infested specimens significantly differ in shell
 landmark-based morphology. Geometric morphometric analyses indicate that
 in two out of three species (Transennella conradina, Abra segmentum): (1)
 PSI and thin-plate spline analyses suggest significant pallial sinus
 reduction in infested specimens relative to non-infested; (2) overall
 morphospace range, estimated by sample-standardized principal component
 (PC) hypervolume, was inflated with the inclusion of infested specimens.
 Consistent with previous studies, results indicate that trematode-induced
 morphological changes may influence the burrowing capabilities of the
 studied bivalves, affecting their ecological functioning and fitness.
 Changes in morphospace induced by trematode parasites hamper species
 delineation and confound morphometric and disparity patterns in the fossil
 record of infestation-prone species. Excluding fossil specimens with
 trematode traces can mitigate those confounding effects. Conversely,
 comparative morphometric analyses of infested and non-infested host
 specimens may allow us to investigate host responses to parasites over
 evolutionary time scales.
description: # Ecological and paleontological implications of trematode-induced
 morphospace inflation and pallial sinus reduction in bivalve hosts Dataset
 DOI: [10.5061/dryad.fqz612k61](https://doi.org/10.5061/dryad.fqz612k61) ##
 Description of the data and file structure All specimens were photographed
 individually using a HAYEAR microscope camera. A metric scale was included
 with each image for calibrated linear measurements for morphological
 analysis. Landmark data was digitized in TPSDig. ### Files and variables
 #### File: R_Script__Raw_Data_(Dryad).zip **Code, Landmark Data Folder:**
 * **Jang et al. 2025.R:** R script of all statistical analyses (e.g.,
 Procrustes Analysis, Principal Component Analysis, bootstrap). *
 **Transennella conradina.tps, Abra segmentum.tps, Chamelea
 gallina.tps:** Raw digitized landmark data. This data is used for
 Procrustes analysis and subsequent Principal Component analysis. * **Jang
 et al. 2025. Spreadsheet.csv:** Spreadsheet including linear measurements,
 species information, trematode pit count, locality, and paleontological
 context. Each row represents one fossil bivalve specimen (species
 Transennella conradina) collected from the Leisey Shell Pit 03A site (Fort
 Thompson Formation, Florida). The table records morphological
 measurements, taphonomic features, taxonomic confidence, and contextual
 site information for each specimen. This table documents **individual
 fossil shells**, combining **taxonomy, measurements, morphology,
 paleoecological damage, and collection context** to support morphometric
 and paleoecological analyses. **Precision Test Folder:** * **Precision
 Test Spreadsheet CSV.csv and Precision Test Spreadsheet.xlsx:**
 Spreadsheet of 50 repeated measurements of the largest (**289184-L(53)**)
 and the smallest (**289163-R(24)**) individuals among all specimens. *
 **Precision Test.R:** Precision test of repeated measurements to assess
 error ranges of the microscope camera used to photograph the specimens.
 All units of measurement are in mm. ## Code/software RStudio (Software
 capable of running R) is used for statistical analysis and data
 visualization. RStudio (2023.12.1+402)  Packages required: * geomorph *
 vegan * dynRB * coin * boot ## Access information Other publicly
 accessible locations of the data: * N/A Data was derived from the
 following sources: * N/A