DOI: 10.5061/dryad.1c59zw3vw
title: Comparing single-species and mixed-species groups in fruit flies: differences in group dynamics but not group formation

description: Mixed-species groups describe active associations among individuals of two
 or more species at the same trophic level. Mixed-species groups are
 important to key ecological and evolutionary processes such as competition
 and predation; and ignoring the presence of other species risks ignoring a
 key aspect of the environment in which social behavior is expressed and
 selected. Despite the defining emphasis of active formation for
 mixed-species groups, surprisingly little is known about the mechanisms by
 which mixed-species groups form. Further, insects have been almost
 completely ignored in the study of mixed-species groups, despite their
 taxonomic importance and relative prominence in the study of
 single-species groups. Here, we measured group formation processes in
 Drosophila melanogaster and its sister species Drosophila simulans. Each
 species was studied alone, and together; and one population of D.
 melanogaster was also studied both alone and with another,
 phenotypically-distinct D. melanogaster population, in a nested-factorial
 design. This approach differs from typical methods of studying
 mixed-species groups in that we could quantitatively compare group
 formation between single-population, mixed-population, and mixed-species
 treatments. Surprisingly, we found no differences between treatments in
 the number, size, or composition of groups that formed, suggesting that
 single-species and mixed-species groups form through similar mechanisms of
 active attraction. However, we found that mixed-species groups showed
 elevated inter-species male-male interactions, relative to
 inter-population or inter-genotype interactions in single-species groups.
 Our findings expand the conceptual and taxonomic study of mixed-species
 groups while raising new questions about the mechanisms of group formation
 broadly.
description: Please see detailed methods section in the manuscript
description: Please see the relevant manuscript for details of how the data
 were collected In the attached dataset, each row is
 data from a single patch in a single video of a single trial. The columns
 have the following meanings: Column A: index
 autogenerated by R combo: letters corresponding to the
 identities of the genotypes present in the trial month:
 the month the video was recorded day: the day the video
 was recorded f1gen: the genotype of 1 set of 5
 females             b = blue; g = green; p = pink; r =
 red; y = yellow m1gen: the genotype of 1 set of 5
 males f2gen: the genotype of the other set of 5
 females m2gen: the genotype of the other set of 5
 males f1col: the paint color identifying the “f1”
 females m1col: the paint color identifying the “m1”
 females f2col: the paint color identifying the “f2”
 females m2col: the paint color identifying the “m2”
 males per: the time of day (“period”) during which the
 video was recorded             1 = morning; 2 =
 evening hour: the hour during the video in which the
 randomly chosen 10-second sample occurred minute: the
 minute during the video in which the randomly chosen 10-second sample
 occurred view: the patch identity ranging from 0 to 3
 for the 4 total patches f1n: number of “f1” females
 recorded on the patch at t=0 m1n: number of “m1” males
 recorded on the patch at t=0 f2n: number of “f2”
 females recorded on the patch at t=0 m2n: number of
 “m2” males recorded on the patch at t=0 m1_m1: number
 of fly-seconds of male-male interactions between m1 males during the
 10-second sample m2_m2: number of fly-seconds of
 male-male interactions between m2 males during the 10-second
 sample m1_m2: number of fly-seconds of male-male
 interactions directed from m1 males to m2 males during the 10-second
 sample m2_m1: number of fly-seconds of male-male
 interactions directed from m2 males to m1 males during the 10-second
 sample m1_f1: number of fly-seconds of male-female
 interactions directed from m1 males to f1 females during the 10-second
 sample m1_f2: number of fly-seconds of male-female
 interactions directed from m1 males to f2 females during the 10-second
 sample m2_f1: number of fly-seconds of male-female
 interactions directed from m2 males to f1 females during the 10-second
 sample m2_f2: number of fly-seconds of male-female
 interactions directed from m2 males to f2 females during the 10-second
 sample groupID: identifies each trial (concatenation of
 sorted combo and date) f1spp: population and species
 information for “f1” females             cos.mel = US
 melanogaster; car.mel = Caribbean melanogaster; sim = simulans
 f2spp: population and species information for “f2”
 females m1spp: population and species information for
 “m1” males m2spp: population and species information
 for “m2” males spp.comb1: indicates combination of
 populations and species present  male.ints: total
 male-male interactions m.within: “within” male-male
 interactions (see manuscript) mf.within: “within”
 male-female interactions (see manuscript) mf.among:
 “among” male-female interactions (see manuscript)
 sorted.combo: same as combo but with duplicates removed for more
 accurate comparison