Data from: Mechanisms for polyandry evolution in a complex social bee
Data files
Feb 29, 2024 version files 1.77 MB
Abstract
Polyandry in social Hymenoptera is associated with reduced within-colony relatedness and increased colony-level ecologic fitness. One explanation for this sees increasing within-nest genetic diversity as a mechanism for improving group task efficiency and colony competitiveness. A queen on her mating flight captures nearly 90% of her breeding population’s allele potential by her tenth effective mating (me~10 males). Under this population allele capture (PAC) model, colony fitness gains track mating number in an asymptotic manner, leveling out after about the tenth mating. A supporting theory we call the genotype composition (GC) model sees genetic novelty at mating levels higher than the me~10 asymptote, the hyperpolyandry zone, resulting from unique genotype compositions whose number are potentially infinite. Colony fitness gains under the GC model will track mating number in a linear manner. We set up field colonies with Apis mellifera queens each instrumentally mated with 1, 2, 4, 8, 16, or 32 males, creating a polyandry gradient bracketing the qualitative divide of me~10, measured tokens of colony level fitness, and collected observation hive data. Our results lead us to conclude that (1) ancestral colony traits fundamental to eusociality (cooperative brood care) respond to mating level changes at or below me~10 in a manner consistent with the PAC model, whereas (2) more derived specialized colony phenotypes (resistance to the non-native parasite Varroa destructor) continue improving with increasing me in a manner consistent with the GC model. By either model, (3) the mechanism for increasing colony fitness is an increase in worker task specialisms and task efficiency.
README: Data from: Mechanisms for polyandry evolution in a complex social bee
https://doi.org/10.5061/dryad.fqz612k0x
Two datasets are attached: (1) Delaplane et al. 2024 BEAS colony strength data and (2) Delaplane et al. 2024 BEAS observation hive data/
Description of the data and file structure
Column identifiers for "Delaplane et al. 2024 BEAS colony strength data"
- A, timepoint. Each of five colony sampling episodes at roughly monthly intervals, June, July, August, September, October, numbered consecutively 1-5. Data were collected from all surviving colonies at each timepoint.
- B, unique field colony identifier
- C, polyandry treatment of queen. Each was instrumentally inseminated with the semen of 1, 2, 4, 8, 16, or 32 males.
- D, unique queen identifier with colored plastic thoracic disks
- E, 24-hr colony counts of parasitic Varroa destructor mites on hive bottom board sticky sheets
- F, colony area (cm2) of brood, all stages
Column identifiers for "Delaplane et al. 2024 BEAS observation hive data"
- A, date of observation
- B, experimental day
- C, field study source colony for labeled experimental young bee cohort
- D, polyandry treatment of queen. In this experiment this value was limited to polyandry=16 or 32 males. Only these two source colonies survived over winter from the field study and were available for the observation hive study.
- E, unique color label for bee cohort. All workers from field colony 49 (poly=16) were marked blue, and all workers from field colony 33 (poly=32) were marked white.
- F, unique bee number within cohort (thoracic labels are both colored and numbered)
- G, patriline ID, genotyping never completed
- H, sum of behaviors reported for focal bee/day
- Columns I-L, for several variables we attempted to observe location in the observation hive where focal bee was observed. These abbreviations here and elsewhere are SBr (on sealed brood), OpHon (on open cells of honey), OpBr (on open brood), or EOE (empty cell on edge of nest). For the published paper we only analyzed summed behaviors across hive locations so that, for instance, we used and reported "daily sum of observed instances of focal bee tending queen" in column M, constituting the sum for that bee/day of columns I-L. This convention follows hereafter. Other variables were recorded without regard to location or only occurred in one location and omit the marker "SUM" (for instance, AE). Yellow highlighted columns N-onward correspond to the 18 objectively observable (ie., we didn't try to guess what "bee with head inside cell" was doing) behaviors named and analyzed in the paper.
Methods
Brood production and parasite numbers
Holistic colony strength measures, considered proxies for fitness, were taken at roughly monthly intervals in Jun, Jul, Aug, Sep, and Oct 2019.
Brood area was derived by visually summing proportions of whole deep frames covered by brood (Delaplane et al. 2013) and converting frames of brood to cm2 by the observation that one deep Langstroth comb (both sides) = 1760 cm2.
Relative numbers of parasitic Varroa destructor mites were found by inserting sticky sampling sheets into bottom board hive inserts and recording the number of Varroa mites trapped after 24 hours (Dietemann et al. 2013).
Worker task distributions
In Mar 2020, we removed combs of emerging brood from one overwintered experimental field colony whose queen was mated at the mo=16 level and from another colony whose queen was mated at the mo=32 level. These were the only two surviving colonies with enough brood to perform the experiment. These combs were labeled by colony of origin, bagged individually, and kept overnight in an incubator at 35°C. The next morning, 100 newly emerged worker bees from each colony were individually numbered with thoracic tags (Mann Lake) color-coded by colony of origin, and all 200 workers introduced to one observation bee hive (day=0) with a non-experimental open-mated queen and 311 of her daughter workers whose number was estimated from a photograph. The resident workers were therefore surrogate hosts to two embedded cohorts for whom we have knowledge of mo. The disadvantage of this arrangement is that it is devoid of the complexity of thigmotaxic and social cues that govern polyandry effects in a normal whole colony. The advantage is that it allows us to compare how different polyandry levels can capture and express specialisms in a common experimental environment. The comb in the observation hive was 1-sided to restrict bees to one surface and ease observations. Beginning on day=1 (27 Mar 2020) and for 18 more days until 14 Apr 2020 one investigator, naïve to the bee labeling designations, observed the marked cohort through the glass for 15 min and recorded each incidence when a focal bee performed one of 18 unambiguously identifiable behaviors: tending queen, watching recruitment dance, dancing, administering vibration dance, receiving vibration dance, shaping cappings, shaping cell edges, receiving grooming, autogrooming, allogrooming, pollen foraging (possessing pollen on its corbiculum), building comb, fanning entrance, engaging in trophallaxis, capping cells, cleaning emerged brood cells, trimming cappings, and antennating another bee.