Field Response
Study title Swash level selects functionally specialized assemblages of beach interstitial meiofauna (Platyhelminthes, Proseriata)
Authors Alejandro Martínez, Diego Fontaneto, Marco Curini-Galletti
Hypothesis Species responses to beach hydrodynamics depend on the presence of certain traits, with the main rationale included in the two opposite scenarios of environmental filtering or functional trait selection. (1) We show that species richness does not differ across beach levels but depends on the characteristics of each beach, using spatially explicit models. (2) We demonstrate that species composition across beach levels depends on the species traits, in addition to geographical and abiotic factors by fitting multivariate generalized linear models. (3) We apply null modelling to highlight that the overall species functional space is smaller than the expected one in the swash level but not in the shoaling and subtidal levels, suggesting an effect of trait-based ecological filtering in the swash level. Species functional contribution to the functional space is also higher in the swash level, reflecting a lower degree of functional redundancy. (4) We show that the observed differences in functional spaces depend on the higher frequency of hydrodynamics-related traits in the species of the swash level, using binomial generalized linear models.
Ecological unit Reflective sandy beaches
Power analysis No
Focal taxa Proseriata (Platyhelminthes)
Resolution Species level
Number of taxa 152
Sampling unit Three beach levels (swash, shoaling and subtidal) within each beach
Number of sampling units 348 sites in 116 beaches
Sampling effort 1130 unique occurrences
Occurrence data type Presence-only
Number of traits 16
Continuous traits used 2
Discrete traits used 10
Binary traits used 4
Fuzzy-coded traits used 0
Trait resolution Coarse
Sample size per species and trait Species level ; Mean value at the species level
Hypothesized function of each trait Morphological traits related to interstitial adaptation, ecology, trophic niche, and reproduction
Intraspecific variation accounted for? No
Data source Original measurements
Data exploration Data visualization, Collinearity assessment, Missing data assessment, Species sampling coverage
Collinearity assessed? We used Gower distance and principal coordinate analysis to extract three trait axes for analyses.
Transformations done? Scaled and centred continuous traits
Missing data accounted for? Yes
Imperfect detection control No
Functional space method Probabilistic hypervolume
Dissimilarity metric used for functional space Gower
Level of analysis Alpha diversity (within group), Beta diversity (between group)
FD method Richness, Species contribution to richness.
Model Spatially explicit generalized linear models, multivariate generalized linear models, binomial generalized linear models, Mantel test; Null-modelling
Effect sizes Standard Effect Size (SES).
Model support SES
Model uncertainty Non applicable
Validation method Non applicable
Preregistration No
Code link Upon acceptance
Community data link Upon acceptance
Trait data link Upon acceptance
Environmental data link
WorldClim 2 database: http://www.worldclim.com/version2 Copernicus database: https://www.copernicus.eu/en/access-data
Data and Code description Software and package version numbers; commented code. The code we provided can reproduce all results, figures and tables.
Date 19 March 2023