DOI: 10.5061/dryad.vmcvdncq0
title: The effect of species composition dissimilarity on plant-herbivore network structure is not consistent over time

description: The structural organization of several antagonistic networks has been
 demonstrated to be largely conserved through time and space even when
 species beta-diversity is high. This might occur either because species
 are replaced by others that fulfill similar network roles, or because
 interaction probabilities are given by species relative abundances rather
 than by their functional traits. Alternatively, if species-specific traits
 are important drivers of realized interactions, any change in species
 composition should promote a certain degree of network structural
 dissimilarity. Here, we used a spatial-temporal system comprising
 asteraceous plants and flower head herbivores from remnants of Brazilian
 Cerrado to investigate whether the relationship between spatial
 beta-diversity of species and network structural dissimilarity changes
 over time. We measured species beta-diversity using Sørensen’s
 dissimilarity index (βsor) and its components of species replacement (β-3)
 and richness differences (βrich). Network structural dissimilarity was
 estimated using three different metrics: connectance, modularity and web
 asymmetry. We show that, in general, the effect of species beta-diversity
 on network structure was time-dependent: while some periods presented a
 positive relationship between spatial beta-diversity and network
 structural dissimilarity, others presented no significant relationship.
 This indicates that functionally similar species may present different
 turnover rates at distinct periods and different non-exclusive processes
 affect plant-herbivore network organization across time.
description: Asteraceae and
 endophagous herbivores were sampled in remnants of Cerrado vegetation in
 the state of São Paulo, southeastern Brazil, between April 2004 and
 February 2005 (Almeida-Neto et al., 2010, 2011). Originally, the
 plant-herbivore interaction data used in this study were recorded in 20
 remnants of Brazilian Cerrado to investigate the influence of invasive
 grass cover on the diversity patterns of asteraceous plants and their
 herbivorous insects (Almeida-Neto et al., 2010, 2011). However, several
 studies relied on this same dataset (entirely or partially) to test other
 hypotheses about the ecological and evolutionary processes shaping
 plant-insect interactions (Bergamini, Lewinsohn, Jorge, &
 Almeida-Neto, 2017; Jorge, Prado, Almeida-Neto, & Lewinsohn, 2014;
 Nobre, Bergamini, Lewinsohn, Jorge, & Almeida-Neto, 2016; Martins,
 Medina, Lewinsohn, & Almeida‐Neto, 2019). In the present study, we
 chose the ten Cerrado remnants with lowest levels of invasive grass cover
 to minimize possible confounding effects among sites. Remnants ranged in
 area from 6 to 150 ha (mean area = 47.4) and the minimum and maximum
 distances between any two sites were 1.8 and 31.5 km, respectively (mean
 distance = 11.3 km). Plant-herbivore networks were sampled during three periods in each site: April-May 2004, August-September 2004 and January-February 2005. These periods were chosen because they include the flowering peaks of the most common and speciose tribes of Asteraceae in the Brazilian Cerrado. The first period (April-May) includes the flowering peaks of the tribes Eupatorieae and Vernonieae. The second period (August-September) includes the flowering peaks of Mutisieae and Gochnatieae, and the third period (January-February) includes the flowering peak of Astereae. Sites were sampled within 35 days in each period. Every study site consisted of 15 transects of 30 x 5 m randomly allocated in relation to the edges of the site.  The local abundance of each plant species was estimated by counting the number of flowering or fruiting individuals within the transect. A maximum volume of 80 ml of flower heads per individual plant was randomly sampled from 20 up to 35 flowering individuals (when available) per species. Sampled flower heads were taken to the laboratory and the emergence of adult herbivores was monitored weekly for at least two months. Due to the lack of taxonomic information on Neotropical Cecidomyiidae (Diptera) and Apionidae (Coleoptera) species, these groups were identified to the genus level and then separated into morphospecies.
description: Herbivore's species names without epithet (e.g. Apion_sp.1)
 do not necessarily match the names in our Table S2. The reason is that the
 names in the original dataset (n = 20 sites) were changed for clarity in
 Table S2, as only herbivore species occuring in the ten Cerrado remnants
 with lowest levels of invasive grass cover were used in our analyses
 (please see Methods section). As such,  Apion species names are
 Apion_sp.1, Apion sp.2, Apion_sp.4, Apion_sp.5, Apion_sp.6, Apion_sp.9,
 Apion_sp.10 and Apion_sp.11 (n =8 Apion species) in the the local networks
 here presented, while the names in Table S2 ranges from Apion sp.1 to
 Apion sp.8. Notice that this pattern holds true for other herbivore genera
 including species without epithets, but this <strong>does not affect
 the </strong><b>reproducibility of our results</b>. In
 fact, calling a species Apion_sp.11 or Apion sp.8 does not have any
 effects on the ecological patterns presented in the main
 paper.