DOI: 10.5061/dryad.jm63xsjb8
title: Data supporting: Methodological overview and data-merging approaches in the study of plant-frugivore interactions

description: Recording species interactions is one of the main challenges in ecological
 studies. Frugivory has received much attention for decades as a model for
 mutualisms among free-living species, and a variety of methods have been
 designed and developed for sampling and monitoring plant–frugivore
 interactions. The diversity of techniques poses an important challenge
 when comparing, combining or replicating results from different sources
 with different methodologies. With the emergence of modern techniques,
 such as molecular analysis or multimedia remote recorders, issues when
 combining data from different sources have become especially relevant. We
 provide an overview of all the techniques used for monitoring
 endozoochorous primary seed dispersal, focusing on a critical appraisal of
 the advantages and limitations, as well as the context-dependency nature,
 of the different methods. We propose five data merging approaches
 potentially useful to combine frugivory interactions data from different
 methodologies. Additionally, we provide two case studies where we combine
 empirical data from plant–animal interactions in Mediterranean shrublands
 using different methodologies. Data merging resulted in a net increase in
 the number of distinct pairwise interactions recorded and compensated
 biases inherent to different methods, resulting in a more robust
 estimation of network topological descriptors. These case studies clarify
 the context-dependent character of the merging approaches, highlighting
 the value of collecting detailed information on the sampling effort in
 terms of reliable results and reproducibility. Finally, we discuss the
 trends with different methodological approaches used in the last decades
 and future perspectives in this field.
description: We used two empirical datasets
 to illustrate data merging approaches, with two different organization
 levels. Both case studies are focused on plant–frugivore interactions
 taking place in the Mediterranean shrubland of Doñana National Park,
 Huelva, Spain. In each case study two sampling methods were used to
 maximise animal–plant interactions detected. The first case is an
 individual-based study on the avian frugivore assemblage of
 <em>Pistacia lentiscus</em> (Anacardiaceae) in El Puntal area,
 where monitoring cameras and DNA-barcoding were used to record
 interactions. Cameras methodology involved placing continuous-monitoring
 cameras (GoPro Hero® 7 model) facing individual plants. Forty individual
 plants were filmed for approximately 2 hours in several runs in different
 days (total of 84.5h). Any avian visitation was recorded as an
 interaction, yielding a total of 397 visitation records. Cameras were
 operative from sunrise for 2h and recording was set at maximum resolution.
 Data resulting from this sampling can be given as total number of records,
 or standardized by sampling time (no. records
 h<sup>-1</sup>). DNA-barcoding methodology (González-Varo et
 al. 2014) was done to faecal samples collected in seed traps located under
 the same forty individual trees. Seed traps were working for 102.7±8.9
 days (mean ±SD) per plant. A total of 1371 faecal samples were analyzed
 (mean no. per plant: 33.8±15.2). Samples were collected regardless of
 whether or not they had seeds, as an indicator of a visitation event. Data
 resulting from this sampling can be given as a total number of records
 with positive identification of a given frugivore species, or standardized
 by the sampling time with seed traps actively operating in the field (no.
 records/trap/day or similar) The second case is a community-based
 study aiming to document species-specific plant–frugivore interactions in
 Hato Ratón, where analysis of fecal samples obtained with mist-netting and
 focal observations were used to detect interactions. Estimation of the
 dietary diversity of frugivore species through mist-netting, relied on
 seeds identification found in bird feces together with microhistological
 techniques to identify the non-seed remains of fruits by examining under
 microscope (40X, 100X) the shape, size, and structures (trichomes, glands)
 of exocarp tissue cells. This allowed not only the identification of fruit
 species when no seeds are present but also the relative volume occupied in
 the sample, so that an estimate of the corresponding number of fruits
 ingested can be derived (Jordano 1988). Between 6-10 mist nets were
 operated weekly for 1–2 days (for a total of 84 sampling days and 4080.5
 mist-net hours), totalling 3541 fecal samples analyzed. Feeding records of
 frugivores visiting fruiting plants were obtained during 1.0 km-length
 walk censuses in the area, with 2–5 censuses carried out per month (123
 sampling days), totalling 89.5 km and 2031 records. These focal
 observations were based on spot censuses where interactions are recorded
 during short stops as the observer advances along a fixed transect. In
 some cases (&lt;15 % of the records) where no handling was observed
 but just the visit to the plant, the number of fruits was approximated
 from data on feeding rate (no. fruits/visit). Data resulting from this
 sampling can be given as total number of records, or standardized by
 sampling time (no. records km<sup>-1</sup> census or no.
 records h<sup>-1</sup> or day<sup>-1</sup>, or
 similar). For more
 information please refer to the Supplementary Material of our manuscript:
 Quintero, Isla & Jordano 2021 Methodological overview and
 data-merging approaches in the study of plant-frugivore interactions.
 Oikos 00: 1–18, 2021. doi: 10.1111/oik.08379. Additional data, codes of analysis,
 final merged datasets, and supplementary figures are available in Zenodo
 (http://doi.org/10.5281/zenodo.4751889) or GitHub repository
 (https://github.com/PJordano-Lab/MS_Oikos_FSD_Monitoring_interactions).
description: pl_bc.csv - Observation matrix obtained with DNA-barcoding method
 in El Puntal case study with <em>Pistacia lentiscus
 </em>individual plants. pl_cam.csv - Observation
 matrix obtained with monitoring cameras method in El Puntal case
 study with <em>Pistacia lentiscus
 </em>individual plants. bc_sampling_effort.csv -
 Sampling effort for DNA-barcoding method in El Puntal case
 study at <em>Pistacia lentiscus
 </em>individual plants. cam_sampling_effort.csv -
 Sampling effort for monitoring cameras method in El Puntal case
 study at <em>Pistacia lentiscus
 </em>individual plants. ----
 hr_mn.csv - Observation matrix obtained with mist-netting method
 in Hato Ratón case study hr_obs.csv - Observation
 matrix obtained with focal observations method in Hato Ratón case
 study