DOI: 10.5061/dryad.sxksn03b4
title: Inequalities in intraspecific plant-lemur interactions drive seed dispersal patterns

description: Biotic interactions occur between individuals and accumulate to shape
 species-level interaction structure across a community. Skewed interaction
 structures, where a few individuals are highly connected and most have few
 interactions, are increasingly identified at the individual-level.
 However, how individual-level interactions accumulate to shape
 species-level interaction outcomes remains unclear. We studied the
 interactions of three frugivorous lemur species (Varecia variegata
 editorum, Eulemur rufifrons, and Eulemur rubriventer) with individual
 plants within a defined area of 4km2. We examined the consistency of
 skewed patterns across time, lemur species, and plant species; compared
 individual- and species-level network structure; investigated the
 intrinsic (DBH and fruit crop size) and extrinsic (fruit availability and
 richness) factors affecting interaction structure; and tested interaction
 structure impact on seed dispersal. We found a substantial and consistent
 skew in the interactions of individual plants with the lemurs, such that
 we observed a single visit for 70% of all plant individuals. This skewed
 pattern was consistent across time, lemur species, and plant species.
 Highly visited plant individuals (with &gt; 20 visits per lemur
 species) occurred infrequently and only for visitation by V. variegata
 editorum and E. rubriventer. These differences in lemur visitation were
 significant at the individual level, and non-significant at the species
 scale. Individual interaction networks were smaller, more specialized, and
 had lower connectivity than their species counterparts. These differences
 demonstrate the importance of individual-level interactions, which contain
 substantial interaction variation not present at the species scale.
 Individual-level interactions were positively influenced only by DBH, and
 fruit crop size across the study area. This skewed interaction structure
 impacted seed dispersal patterns, such that seeds were most likely to be
 deposited within 15 m of highly visited plants. Our results highlight the
 importance of individual-level interaction variation for seed dispersal
 mutualisms and call for further study on the consistency of such patterns
 across ecosystems.
description: Fieldwork took place in the Valohoaka research area within
 Ranomafana National Park (RNP) in southeastern Madagascar. Ranomafana
 National Park is composed of protected montane rainforest with an
 elevation ranging from 600 – 1500 m (Wright and Andriamihaja 2002) and
 yearly rainfall averaging 2835mm (monthly averages 10-1200mm) (Dunham,
 Erhart, and Wright 2011). Our field site was a 2,000 X 2,000 m (4
 km<sup>2</sup>) forest section where previous observations of
 all three focal lemur species (<em>Eulemur rufifrons</em>,
 <em>Eulemur rubriventer </em>and <em>Varecia Variegata
 editorum</em>) facilitated access to habituated populations
 (Razafindratsima, Jones, and Dunham 2014; Tonos et al. 2021). These
 frugivorous lemur species are known to play a substantial role as seed
 dispersers for the native plant community, which is composed of at least
 330 plant species (Razafindratsima and Dunham 2015).
 Data collection took place from June 2022 through December 2023,
 and was organized in expeditions of 11 days each. During these
 expeditions, we undertook two days of phenology observations and nine days
 of lemur foraging observations. On average, we undertook two expeditions
 per month, though local holidays, logistical constraints, and inclement
 weather occasionally intervened with this schedule. We completed 31
 expeditions during which we conducted 6-11 primate observation days, for a
 total of 280 days. 1.1        Primate
 observations For each lemur species, a dedicated team
 of three observers conducted nine continuous days of direct observations
 per expedition. Each observation day consisted of 8 hours of continuous
 data collection on a group of the team’s target species. At the beginning
 of each observation day, each team entered the study area, located a group
 or individual of their target species, and then began the 8-hour
 observation period. Shorter observation periods occurred when lemur groups
 were found late enough that observations were cut off by nightfall or when
 lemur groups were lost due to faster-than-usual travel speeds, terrain, or
 weather. In the case that a lemur group was lost, the team would search
 for the same, or another group, of the same species within the study area
 and resume observations. When a lemur group was found, an individual was
 selected as a focal for feeding and seed-dispersal observations. As lemur
 groups of the <em>Eulemur</em> species tend to forage and
 travel together cohesively (Pyritz, Kappeler, and Fichtel 2011; Tecot and
 Romine 2012), a randomly selected individual is a reasonable proxy for the
 broad group foraging and seed-dispersal behaviors. For <em>V.
 variegata</em> observations focused on a single individual (rather
 than a group) was necessary due to their flexible fission-fusion dynamics
 in which group composition changes readily and individuals are often alone
 (Baden, Webster, and Kamilar 2016). At any instance of feeding
 (frugivory)(Appendix S1: Figure S1) or seed dispersal (defecation
 containing seeds) by the focal, we collected the time of the event, the
 geographic location using a GPS device, and the species and individual
 identifier of the tree where the lemur was located. For feeding events, we
 additionally noted the plant part and species consumed (may differ from
 the tree species in the case of vines and epiphytes), the diameter at
 breast height (DBH), and the fruiting phenology status of the plant
 consumed. For epiphytes and vines, the identifying tag was placed on the
 host tree, so that a particular plant is indexed by a combination of tree
 tag and species name. Fruiting phenology was graded on a 5-category system
 in which a zero is given for no fruits, 1 corresponded to 1-25% of the
 crown containing fruit, 2 for 25-50%, 3 for 50-75% and 5 for
 <em>&gt;</em>75% as utilized in similar studies (Dunham et
 al. 2018). 1.2        Phenology We
 established 27 transects (100 x 4 meters) within our 4 km<sup>2
 </sup>study area in May 2023. The transects were placed by selecting
 30 random start points (<em>&gt;</em>100m apart) and then
 randomly assigning a direction (selecting a number between 0 and 360
 degrees). We established the transects by navigating to the start point
 and extending the transect line 100 meters in the selected bearing, using
 a compass and measuring tape. Three of the proposed transects were removed
 during this process due to the steepness of the terrain and the presence
 of large boulders. Along each transect (within 2 meters of the established
 center line at each side), we marked (with a unique numbered aluminum tag)
 and measured the DBH and height of every tree with a DBH
 <em>&gt;</em>10 cm. During the first two days of every
 expedition after transect establishment, we survey the fruiting phenology
 of every plant along our transects (tagged or not), recording the species,
 individual tag (as relevant), DBH, height, transect section (10 sections
 per transect of 10 m each). For each plant, we record the presence and
 extent of each phenological event observed (new leaves, budding,
 flowering, and fruiting). The extent of the phenology event is rated on
 the same five-category system as above. Using these
 phenology data, we estimated the total fruit availability index (FAI) for
 each expedition, as well as the FAI for each plant species within each
 expedition. The FAI was calculated according to the methods of (Sengupta
 and Radhakrishna 2016) by multiplying the mean density across all
 transects to the mean basal area and mean fruiting score across all
 individuals of a species within each expedition. For total expedition FAI,
 species specific values were summed for each expedition.
description: # Inequalities in intraspecific plant-lemur interactions drive seed
 dispersal patterns Dataset DOI:
 [10.5061/dryad.sxksn03b4](https://doi.org/10.5061/dryad.sxksn03b4) ##
 Description of the data and file structure These data describe the
 interactions of individual plants with lemur frugivores who consume their
 fruit collected using direct observations. The dataset describes the
 number of times each of three lemur species visited a plant individual
 within the Valo research area in Ranomafana National Park. ### Files and
 variables #### File: FAME_code.Rmd **Description:** R code used for all
 statistical analysis done for this project. Each of the data files in this
 repository are formatted for specific analysis and can be identified by
 the document name, and the object name within the code.  #### File:
 individual_plants.csv **Description:**  ##### Variables *
 plant_id: Individual plant identification made from a combination of
 species name and tree tag. Each plant individual may appear multiple times
 if it had lemur interactions on multiple expeditions * species: Species of
 the lemur group which visited this plant individual for frugivory. The
 species is either Varecia variegata, Eulemur rufifrons, or Eulemur
 rubriventer * visits: total number of frugivory visits to this plant
 individual by the given lemur species * f_visits: total number of
 frugivory visits to this plant individual by the given lemur species *
 DBH: The individual tree's diameter at breast height * pspecies: the
 scientific name for the individual tree's species *
 expeditions_visited: The ID number for the expedition within which the
 plant individual x lemur species interaction took place. Each expedition
 corresponds to an observation window of 6-11 days. #### File:
 individual_plants_analysis_phen.csv **Description:**  ##### Variables *
 plant_id: Individual plant identification made from a combination of
 species name and tree tag. Each plant individual may appear multiple times
 if it had lemur interactions on multiple expeditions * expedition: The ID
 number for the expedition within which the plant individual x lemur
 species interaction took place. Each expedition corresponds to an
 observation window of 6-11 days. * visits: Total number of visits (for
 frugivory, sleep or dispersal) to this plant individual by all lemur
 species in the given expedition * DBH: The individual tree's diameter
 at breast height * FR_max: The peak fruiting value for the individual
 plant within the given expedition * f_visits: Total number of frugivory
 visits to this plant individual by all lemur species in the given
 expedition * basal.area: basal area of the individual tree * fai: fruit
 availability index value for the individual tree * pspecies: scientific
 name of the plant individual's species * fai_exp: total fruit
 availability index across all plants during the given expedition * fai_sp:
 total fruit availability index value for the individual tree's
 species within the given expedition * richness: richness of all fruiting
 plants during the given expedition * richness_scaled: standardized
 richness obtained using R's scale() function * f_zero: Frugivory
 visitation shifted (by subtracting 1) to represent the number of re-visits
 * DBH_scaled: standardized value obtained using R's scale() function
 * FR_scaled: standardized value obtained using R's scale() function *
 fai_exp_scaled: standardized value obtained using R's scale()
 function * fai_sp_scaled: standardized value obtained using R's
 scale() function #### File: plant_individual_matrix.csv **Description:** 
 ##### Variables * plant_individual: Individual plant identification made
 from a combination of species name and tree tag. Each plant individual may
 appear multiple times if it had lemur interactions on multiple expeditions
 * Varecia variegata editorum: Number of frugivory visits by the named
 lemur species * Eulemur rufifrons: Number of frugivory visits by the named
 lemur species * Eulemur rubriventer: Number of frugivory visits by the
 named lemur species #### File: individual_plants_analysis.csv
 **Description:**  ##### Variables * plant_id: Individual plant
 identification made from a combination of species name and tree tag. Each
 plant individual may appear multiple times if it had lemur interactions on
 multiple expeditions * count: a count of the number of lemur species that
 visited the plant (for a total possible value of 3) * mean_vis: mean
 number of visits per lemur species * frug_visits: total number of
 frugivory visits to this plant individual by all lemur species * Eulemur
 rufifrons: total number of frugivory visits to this plant individual by
 the given lemur species * Eulemur rubriventer:total number of frugivory
 visits to this plant individual by the given lemur species * Varecia
 variegata editorum:total number of frugivory visits to this plant
 individual by the given lemur species * DBH: The individual tree's
 diameter at breast height * mean_fruiting_score: mean fruiting score (out
 of a value between 0-5) across the whole study * pspecies: scientific name
 of the plant individual's species * abundance: NA * var: 0 indicates
 no visits by Varecia variegata editorum, 1 indicates any visits * ruf: 0
 indicates no visits by Eulemur rufifrons, 1 indicates any visits * rub:0
 indicates no visits by Eulemur rubirventer, 1 indicates any visits *
 totals: a count of the number of lemur species that visited the plant (for
 a total possible value of 3) #### File:
 individual_plants_expedition_analysis.csv **Description:**  #####
 Variables * expedition: The ID number for the expedition within which the
 plant individual x lemur species interaction took place. Each expedition
 corresponds to an observation window of 6-11 days. * plant_id: Individual
 plant identification made from a combination of species name and tree tag.
 Each plant individual may appear multiple times if it had lemur
 interactions on multiple expeditions * count: a count of the number of
 lemur species that visited the plant (for a total possible value of 3) *
 mean_vis: mean number of visits per lemur species * frug_visits: total
 number of frugivory visits to this plant individual by all lemur species *
 Eulemur rufifrons: total number of frugivory visits to this plant
 individual by the given lemur species * Eulemur rubriventer:total number
 of frugivory visits to this plant individual by the given lemur species *
 Varecia variegata editorum: total number of frugivory visits to this plant
 individual by the given lemur * DBH:The individual tree's diameter at
 breast height * max_fruiting_score: max fruiting score (out of a value
 between 0-5) across the whole study * pspecies: scientific name of the
 plant individual's species * var: 0 indicates no visits by Varecia
 variegata editorum, 1 indicates any visits * ruf: 0 indicates no visits by
 Eulemur rufifrons, 1 indicates any visits * rub:0 indicates no visits by
 Eulemur rubirventer, 1 indicates any visits * totals: a count of the
 number of lemur species that visited the plant (for a total possible value
 of 3) #### File: plant_species_matrix.csv **Description:**  #####
 Variables * plant_species: scientific name of the plant individual's
 species * Eulemur rufifrons: total number of frugivory visits to this
 plant species * Eulemur rubriventer:total number of frugivory visits to
 this plant species * Varecia variegata editorum: total number of frugivory
 visits to this plant species ## Code/software excel and R ## Access
 information Other publicly accessible locations of the data: * 
 
 Data was derived from the following sources: *