DOI: 10.5061/dryad.vt4b8gtv4
title: Geographical variation in the trait-based assembly patterns of multitrophic invertebrate communities

description: It has been argued that the mechanisms structuring ecological communities
 may be more generalizable when based on traits than on species identities.
 If so, patterns in the assembly of community-level traits along
 environmental gradients should be similar in different places in the
 world. Alternatively, geographic change in the species pool and regional
 variation in climate might result in site-specific relationships between
 community traits and local environments. These competing hypotheses are
 particularly untested for animal communities. Here we test the geographic
 constancy of trait-based assembly patterns using a widespread
 multi-trophic community: aquatic macroinvertebrates within bromeliads. We
 used data on 615 invertebrate taxa from 1656 bromeliads in 26 field sites
 from Mexico to Argentina. We summarized invertebrate traits with four
 orthogonal axes, and used these trait axes to examine trait convergence
 and divergence assembly patterns along three environmental gradients:
 detrital biomass and water volume in bromeliads, and canopy cover over
 bromeliads. We found no overall signal of trait-based assembly patterns
 along any of the environmental gradients. However, individual sites did
 show trait convergence along detrital and water gradients, and we built
 predictive models to explore these site differences. Sites that showed
 trait convergence along detrital gradients were all north of the Northern
 Andes. This geographic pattern may be related to phylogeographic
 differences in bromeliad morphology. Bromeliads with low detritus were
 dominated by detritivorous collectors and filter feeders, where those with
 high detritus had more sclerotized and predatory invertebrates. Sites that
 showed the strongest trait convergence along gradients in bromeliad water
 were in regions with seasonal precipitation. In such sites, bromeliads
 with low water were dominated by soft-bodied, benthic invertebrates with
 simple life cycles. In less seasonal sites, traits associated with
 short-term desiccation resistance, such as hard exoskeletons, were more
 important. In summary, we show that there are strong geographic effects on
 the trait-based assembly patterns of this invertebrate community, driven
 by the biogeography of their foundational plant species as well as by
 regional climate. We suggest that inclusion of biogeography and climate in
 trait-based community ecology could help make it a truly general theory.
 (excerpted from Srivastava, DS et al. 2022. Geographical variation in the
 trait-based assembly patterns of multitrophic invertebrate communities.
 Functional Ecology)
description: <strong>Bromeliad and
 macroinvertebrate data</strong>
 We compiled data on the
 aquatic macroinvertebrates in tank bromeliads previously sampled in 26
 different sites throughout the natural distribution of the tank bromeliads
 (Bromeliaceae family). Field sites were distinct from each other in space,
 elevation and the species composition of invertebrate communities. For
 every bromeliad, all water and detritus contained in the plant were
 removed, either by dissecting the plant or by pipetting. The water and
 detritus were examined for aquatic macroinvertebrates in small
 size-fractioned aliquots in white trays. Macroinvertebrates were
 identified to morphospecies in the field, and subsequently to the lowest
 possible taxonomic level. The detritus was oven-dried and weighed to
 determine dry mass. Bromeliads were sampled across a range of habitats,
 from exposed <em>restinga </em>(coastal sand-based shrub
 habitat) in Brazil to cloud forests on Caribbean mountaintops to
 rainforests in Central America. As no bromeliad genus was found in all
 field sites, we sampled the most common genera in sites.
 Our analysis included
 three environmental characteristics of each sampled bromeliad: (1) the dry
 mass of all detritus in the bromeliad (hereafter “detritus”, measured in
 grams); (2) the volume of standing water in each bromeliad on the day of
 sampling (hereafter “water”, measured in mL); (3) the openness of the
 canopy above the bromeliad (hereafter “canopy”, a binary variable with 1 =
 open canopy and 0 = closed canopy). These variables were chosen because
 previous site-specific research had established that they were important
 environmental drivers of community structure and function.
 <strong>Trait data</strong>
 Our analysis considers
 interspecific, but not intraspecific, differences in traits. In Céréghino et
 al. (2018), each
 bromeliad invertebrate morphospecies was scored in terms of twelve traits:
 aquatic developmental stage, body form, maximum body size, cohort
 production interval, dispersal mode, food, feeding group, locomotion,
 morphological defence, reproduction mode, resistance forms and respiration
 mode.Each trait was represented by several modalities or categories (e.g.
 the modalities for the trait “dispersal mode” were passive and active),
 and the affinity of the taxa for each modality was fuzzy coded. In total,
 the 12 traits were represented by 64 modalities.  Céréghino et
 al. (2018) reduced these 64 trait modalities to four
 orthogonal axes using PCA (original data:https://knb.ecoinformatics.org/view/doi:10.5063/F1VD6WMF). Since then, there have been modest updates to the trait data: some trait scores were improved, the number of missing values reduced, a few microscopic or terrestrial species were removed, and the taxonomic resolution of some species identifications was improved. We therefore reran the PCA analysis on the updated trait matrix, using the same R script as in Céréghino et al. (2018), and used the first four axes in our current study. <strong>Site information</strong> We collated information on biogeographic, bioclimatic, and sampling characteristics of each field site in order to better contextualize differences among sites. Biogeographic characteristics included position north and north west versus south and southeast of the Northern Andes (simplified hereafter as north versus south of Andes). The Northern Andes are known to be a dispersal barrier for both bromeliads  and bromeliad invertebrates. Although the Southern and Central Andes could be a potential barrier between the west coast and center of South America, we have no bromeliad data from the former and so do not analyse these mountain ranges. We examined species pool richness, estimated with Chao’s method (implemented in the vegan R package), to test if richer sites had stronger trait-environment matching. From the WorldClim database, we extracted site-specific estimates of four bioclimatic variables that a previous study (Guzman et al., 2020) found to underlie spatial variation in bromeliad macroinvertebrate traits: mean diurnal range in temperature (BC2), temperature annual seasonality (BC4), precipitation annual seasonality (BC15) and precipitation of the driest quarter (BC17). WorldClim data was extracted at the 1km2 scale; when field sites exceeded 1 km2 in size we averaged data over the relevant 1 km2 pixels. Finally, we examined sampling characteristics of each site, including the number of bromeliads sampled (which affects the power of tests) and the site mean of the focal environmental gradient (in case trait-environment relationships differ with site position on gradient). <strong>Data processing</strong> We organized the abundance data using the R package <em>fwdata</em> (developed by A.A.M.M, https://github.com/SrivastavaLab/fwdata). We then converted abundances to biomass by multiplying abundance by the estimated per capita biomass of each morphospecies, based on taxon-specific allometric relationships, using the hellometry R package (provided courtesy of P. Rogy, https://github.com/pierrerogy/hellometry). <strong> Summary</strong> In sum, the dataset consists of information on environmental attributes of bromeliads (n = 1656), macroinvertebrate morphospecies (n = 615), macroinvertebrate traits (n = 64), local environmental gradients (n = 3) and field sites (n = 26). (text excerpted from Srivastava, DS et al. 2022. Geographical variation in the trait-based assembly patterns of multitrophic invertebrate communities. Functional Ecology)
description: These data, in combination with archived R scripts, allow
 reproducibility of the results reported in the 2022 Functional Ecology ms
 "Geographical variation in the trait-based assembly patterns of
 multitrophic invertebrate communities" by DS Srivastava and
 co-authors. A <strong>README.TXT</strong> file is included
 with full metadata for all data files. The data files include input files
 for the R Scripts (visits_owners.csv, bromeliads_syncsa_ready.csv,
 biomass_syncsa_ready.csv, traits_pca_ready.csv, site_covariates.csv) as
 well as three output files (RES_pca_individuals_0.7.7_ranks_cleaned.txt,
 allout_lastrun.csv, allaxes1234_lastrun.csv). We include the output files
 linked to the published results for full reproducibility as
 permutation-based results can change slightly between runs.
 <br><br>Although this data is being made publicly available,
 we do ask that those intending to reuse the data for publication purposes
 to please first contact the data collectors (see
 "visits_owners.csv" file for names and emails of data
 collectors). We can provide you with valuable context and system-specific
 knowledge that will help you make best use of the data. We also point out
 that many data collectors are from the Global South and that there is a
 history in ecology of neocolonial practices regarding the unacknowledged
 flow of data from poorer to wealthier countries.
 <br><br><strong>Spatial structure of
 data</strong><br><br>We defined a distinct
 <strong>site</strong> as one that was distinct in terms of:
 space, elevation and taxonomic identity of its species pool. All
 bromeliads surveyed within a site must occur in an area &lt;3.5 km in
 linear dimension and within a 300 m range of elevation. The invertebrate
 species pool should also be &gt;50% dissimilar (Jaccard dissimilarity,
 based on presence-absence) between adjacent sites. For example, bromeliads
 surveyed along a transect covering an elevation gradient (Sonadora
 transect, Puerto Rico) are assigned to a low <br>elevation
 (400-700m) and high elevation (750-1000m) site based on differences in
 elevation and dissimilarity in the invertebrate
 species.<br><br>A <strong>dataset</strong> is
 defined as a distinct combination of time and location.  For example, if
 one habitat in a site was surveyed in two different years, these would be
 considered distinct datasets with one visit each. As datasets are often
 defined slightly differently by different data collectors, this is a less
 consistent spatial unit than sites and so is not the basis of our
 analysis.<br><br><strong>Visits </strong>are
 defined as a survey of bromeliad macroinvertebrates distinct in habitat,
 time and location. Multiple visits may be nested within a dataset. If two
 distinct habitats were surveyed at the same location at the same time of
 year, these would also be considered two visits within a dataset.
 <br><br><strong>Missing values</strong> are
 indicated by NA in all files.