DOI: 10.5061/dryad.ht76hdrr4
title: Insect seed-predator networks respond positively to restoration on a tropical island

description: When non-native species invade ecosystems, coevolved plant-animal
 interactions and associated ecological functions are altered, often to the
 detriment of local biodiversity. While mutualistic interactions can
 benefit from —and assist with— ecological restoration through the removal
 of non-native species, community-level changes in antagonistic
 interactions due to restoration are less well understood. Insect seed
 predators provide important ecosystem functions, but can also have
 antagonistic effects through pre-dispersal seed predation which can cause
 fruit abortion or premature fruit drop, potentially affecting plant
 community composition. Here, we used a network approach and data on
 trophic interactions from a large-scale field experiment to investigate
 the differences in insect seed predator communities between native
 restored sites (where non-native plants were removed) and unrestored sites
 dominated by non-native plants on the island of Mahé, Seychelles. Restored
 sites contained more individuals and species of seed predators (up by 81%
 and 50% respectively), and experienced a greater predation intensity (1.06
 ± 0.53 vs. 0.27 ± 0.09), and predator specialisation compared to
 unrestored sites. The proportion of predated samples was similar between
 treatments (~14%). Beta diversity, measured as species and interaction
 turnover, increased at restored sites. Synthesis and applications: Our
 findings imply that vegetation restoration generates marked biodiversity
 benefits on native seed predator communities and their interactions.
 However, removing non-native plants did not result in the elimination of
 non-native seed predators, which might require targeted control measures.
 Our results highlight the importance of considering the effects of
 restoration on antagonistic interactions, in addition to those reported
 for pollination and seed dispersal services. Management practices should
 aim to control plant invasions for the conservation of native plant
 communities that serve as resources and refugia both for mutualists (e.g.
 seed dispersers, pollinators) and native insect seed-predator antagonists,
 both of which benefit native ecosystem function.
description: The study was carried out on eight inselbergs (steep-sided
 granitic rock outcrops) of ca. 1 ha on Mahé, the largest granitic island
 of the Seychelles archipelago, Indian Ocean (- 4.6953°, 55.4999°, 154
 km<sup>2</sup>, 900 m a.s.l.). To restore inselberg
 communities, all non-native woody plants were removed from four of the
 inselbergs between 2011 and 2012 by cutting individual plants and applying
 herbicide to cut stumps (Kaiser-Bunbury et al., 2015), with follow-up
 control thereafter. The other four inselbergs remained unchanged with both
 native and non-native species (Kaiser-Bunbury et al., 2017).
 To estimate fruit availability at each site, we recorded monthly
 fruit abundance by counting all ripe fruits of woody fleshy-fruited plant
 species that are mainly dispersed by endozoochory along fixed linear
 transects. To collect seed predators, we sampled fleshy
 fruits monthly at the eight study sites over one year (Sep. 2018 to Aug.
 2019). Samples of ten fruits were collected opportunistically from all
 individuals of fleshy-fruited species with &gt;10 fruits at each
 site. For further information, please see the
 "Material and methods" section in the associated
 manuscript
description: # Insect seed-predator networks respond positively to restoration on a
 tropical island
 [https://doi.org/10.5061/dryad.ht76hdrr4](https://doi.org/10.5061/dryad.ht76hdrr4) ## Description of the data and file structure **README** **Title:** Insect seed-predator networks respond positively to restoration on a tropical island **Authors:** Alba Costa, Ruben Heleno, Yanick Dufrene, Eleanor Huckle, Sara Beatriz Mendes, Andrew E. Whittington, Frank J.F. van Veen, Christopher N. Kaiser-Bunbury **Journal:** Journal of Applied Ecology **Contact Author:** Alba Costa; Email: [ac920@exeter.ac.uk](mailto:ac920@exeter.ac.uk); [a.costa@csic.es](mailto:a.costa@csic.es) **DATASETS** fruit_abundance.csv Data on fruit abundance of ripe fleshy-fruited plant species collected monthly along linear transects for 12 consecutive months, from September 2018 to August 2019, on the island of Mahé, Seychelles. Variables: ·       **date:** date of record ·       **julian & z_julian: **julian day and scaled julian day, respectively ·       **site**: identity code of each site (“ber”: Bernica, “cas”: Casse Dent, “cop”: Copolia, “res”: La Reserve, “ros”: Rosebelle, “sal”: Salazie, “tea”: Tea Plantation, “tro”: Trois Frères) ·       **treatment**: restoration status (“restored”: sites cleared of all exotic plants between 2011 and 2012; “unrestored”: sites not cleared of exotic plants) ·       **transect**: transect identity ·       **section**: identity of 25-meter section within the transect ·       **plant_spp**: plant species ·       **plant_origin**: origin of the plant species (“native”, “exotic”). In publication, “exotic” = “non-native” ·       **fruit_crop**: total number of fruits recorded ·       **plant_individuals**: number of plant individuals of each species recorded ·       **fpc**: fruits per cápita or fruit_crop/plant_individuals SP_richness.csv Species richness of pre-dispersal insect seed predator reared from fruits collected for 12 consecutive months, from September 2018 to August 2019, on the island of Mahé, Seychelles. Variables: ·       **treatment**: restoration status (“restored”: sites cleared of all exotic plants between 2011 and 2012; “unrestored”: sites not cleared of exotic plants) ·       **site**: identity code of each site (“ber”: Bernica, “cas”: Casse Dent, “cop”: Copolia, “res”: La Reserve, “ros”: Rosebelle, “sal”: Salazie, “tea”: Tea Plantation, “tro”: Trois Frères) ·       **plant_spp**: plant species ·       **n: **number of seed predator species SP_abundance.csv Species richness of pre-dispersal insect seed predator reared from fruits collected for 12 consecutive months, from September 2018 to August 2019, on the island of Mahé, Seychelles. Variables: ·       **treatment**: restoration status (“restored”: sites cleared of all exotic plants between 2011 and 2012; “unrestored”: sites not cleared of exotic plants) ·       **site**: identity code of each site (“ber”: Bernica, “cas”: Casse Dent, “cop”: Copolia, “res”: La Reserve, “ros”: Rosebelle, “sal”: Salazie, “tea”: Tea Plantation, “tro”: Trois Frères) ·       **plant_spp**: plant species ·       **species: **seed predator species or morphospecies ·       **origin: **seed predator biogeographical origin ·       **number: **number of seed predator individuals SP_attack_rates.csv Proportion of fruit samples (10 fruits) predated by pre-dispersal seed predators. Samples were collected from September 2018 to August 2019, on the island of Mahé, Seychelles. Variables: ·       **site**: identity code of each site (“ber”: Bernica, “cas”: Casse Dent, “cop”: Copolia, “res”: La Reserve, “ros”: Rosebelle, “sal”: Salazie, “tea”: Tea Plantation, “tro”: Trois Frères) ·       **month**: month of data collection ·       **treatment**: restoration status (“restored”: sites cleared of all exotic plants between 2011 and 2012; “unrestored”: sites not cleared of exotic plants) ·       **plant_spp**: plant species ·       **plant_origin**: origin of the plant species (“native”, “exotic”). In publication, “exotic” = “non-native” ·       **sample_code**: identity of sample containing 10 fruits ·       **predation**: predated sample = 1, non-predated sample = 0 ·       **no_insects**: number of seed-predator insect individuals found in sample ·       **fruit_crop**: total number of fruits recorded predation_intensity.csv Predation intensity data, measured as mean abundance of seed predators per fruit. Samples were collected from September 2018 to August 2019, on the island of Mahé, Seychelles. Variables: ·       **site**: identity code of each site (“ber”: Bernica, “cas”: Casse Dent, “cop”: Copolia, “res”: La Reserve, “ros”: Rosebelle, “sal”: Salazie, “tea”: Tea Plantation, “tro”: Trois Frères) ·       **treatment**: restoration status (“restored”: sites cleared of all exotic plants between 2011 and 2012; “unrestored”: sites not cleared of exotic plants) ·       **plant_spp**: plant species ·       **plant_origin**: origin of the plant species (“native”, “exotic”). In publication, “exotic” = “non-native” ·       **sample_code**: identity of sample containing 10 fruits ·       **insect_abun**: number of insects per sample of 10 fruits ·       **fruits_col**: number of fruits per sample ·       **insect_abun_fruit**: number of seed-predator insect individuals per fruit ·       **fruit_crop**: total number of fruits recorded SP_plant_interactions.csv Data on the frequency of interactions in matrix format between plants (rows) and pre-dispersal seed predator insects (columns) obtained from fruit samples (10 fruits) collected on eight inselberg plant communities (4 restored and 4 unrestored) on the island of Mahé, Seychelles, over one year (Sep. 2018 to Aug. 2019). Each matrix cell depicts the number of individuals of a seed predator insect found in the samples of a given plant species. The sheet “SP_pooled_freq” contains the data for all sites, “SP_restored_freq” only the interaction data for the four restored sites, and “SP_unrestored_freq” for the unrestored sites. ## Code/software All analyses were conducted in R 4.3.2 (R Core Team, 2022). Poisson generalized mixed effects models (GLMMs) were fitted using the package “lme4” (Bates et al., 2015), negative binomial and truncated poisson models using “glmmTMB” (Brooks et al., 2017), and LMMs using the ‘lmertest’ package (Kuznetsova et al., 2017). Model design and selection followed the recommendations by Zuur et al. (2009) and Harrison et al. (2018).