1. Ecology
  2. Evolutionary Biology
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Temperature stress induces mites to help their carrion beetle hosts by eliminating rival blowflies

  1. Syuan-Jyun Sun  Is a corresponding author
  2. Rebecca M Kilner
  1. Department of Zoology, University of Cambridge, United Kingdom
  2. Institute of Ecology and Evolutionary Biology, National Taiwan University, Taiwan
Research Article
Cite this article as: eLife 2020;9:e55649 doi: 10.7554/eLife.55649
5 figures and 2 additional files

Figures

Figure 1 with 2 supplements
Reproductive success of burying beetles and blowflies under field conditions in relation to ambient air temperature, across the three different mite treatments.

Shaded regions represent 95% confidence intervals, and solid and dashed lines represent statistically significant and non-significant regression lines from GLMM, respectively. Each datapoint represents one breeding event.

Figure 1—figure supplement 1
Spatial distribution of breeding sites (yellow dots) used in the field experiment at the study in Madingley Wood, Cambridge, UK (Latitude: 52.22730°; Longitude: 0.04442°).

Image taken from GoogleMaps.

Figure 1—figure supplement 2
Schematic side-view representation of the experimental setup used for each breeding event in the field (dimensions are in cm).

One flowerpot was partially buried in the ground, filled with compost (planting soil) and covered above with a second inverted flowerpot, perforated on the top to let in wild blowflies. The whole apparatus was surrounded by wire mesh, pegged in the ground, to prevent disruption by scavengers.

Figure 2 with 2 supplements
Burying beetle reproductive success under lab conditions in relation to ambient air temperature in the incubator, without and with blowflies, and across three different mite treatments.

Sample sizes are shown above each boxplot. Boxplots show median (solid line), first quartile (bottom of box), third quartile (top of box), values that fall within 1.5 times of the interquartile range (dotted lines), and outliers (open circles). Each datapoint represents one breeding event.

Figure 2—figure supplement 1
The daily mean, maximum, and minimum ambient air temperature in Madingley Woods during the field experiments conducted in 2016 and 2017.

Day 0 is June 1. Dashed lines correspond to the high, mid, and low temperatures used in the laboratory experiments.

Figure 2—figure supplement 2
Reproductive success of mites in relation to temperature, without and with blowflies and across the temperature treatments.

Data for each mite treatment (10 and 20 mites) are shown separately. Sample sizes are as indicated above each boxplot. Boxplots show median (solid line), first quartile (bottom of box), third quartile (top of box). Values that fall within 1.5 times of the interquartile range (dotted lines), and outliers (open circles). Each datapoint represents one breeding event.

Blowfly reproductive success in relation to temperature in the presence of (A) 0 mites, (B) 10 mites and (C) 20 mites.

Sample sizes are as indicated above each bar. Boxplots show median (solid line), first quartile (bottom of box), third quartile (top of box), values that fall within 1.5 times of the interquartile range (dotted lines), and outliers (open circles). Each datapoint represents one breeding event.

Figure 4 with 1 supplement
Effect of temperature on blowfly and burying beetle performance during carcass preparation.

(A) The effect of temperature on blowfly development rate (n = 13 mouse carcasses for each temperature treatment) and (B–D) the relationship between number of blowfly larvae and roundness of the carcass for the low, mid, and high temperature treatment (n = 23, 23, and, 22 mouse carcasses, respectively). Boxplots show median (solid line), first quartile (bottom of box), third quartile (top of box), values that fall within 1.5 times of the interquartile range (dotted lines), and outliers (open circles). The shaded region represents 95% confidence interval, and the line represents statistically significant regression line from GLM.

Figure 4—figure supplement 1
Effect of temperature on blowfly reproductive performance.

(A) Number of blowfly larvae produced and (B) rate of carcass consumption by blowfly larvae. Boxplots show median (solid line), first quartile (bottom of box), third quartile (top of box), values that fall within 1.5 times of the interquartile range (dotted lines), and outliers (open circles). Each datapoint represents one breeding event. n = 13 mouse carcasses for each temperature treatment.

A summary of the experimental results, showing how the interactions between burying beetles, mites, and blowflies change in response to an increase in temperature stress (caused by temperatures that are higher or lower than average).

Direct interactions between species are shown with solid lines while indirect interactions are shown with dashed lines. The arrow points to the species whose fitness is affected by the focal species. The signs (+/-) indicate positive or negative effects on fitness. Our overall conclusion is that a temperature-enhanced threat from blowflies causes mites to become protective mutualists of their burying beetle hosts.

Additional files

Supplementary file 1

Results from the final models for each variable analysed.

(a) Results from the final models for the reproductive success of beetles, blowflies, and mites in the field experiment. The final models used were: glmer.nb(Number of larvae ~ Mite treatment*(poly(temperature,degree = 2)[,2]+ poly(temperature,degree = 2)[,1])+Carcass mass+(1|site)+(1|year)). Models analyzing burying beetle larvae and blowfly larvae were both sufficient to reject the null hypotheses, with 81.3% and 98.6% power, respectively, whereas the model analyzing mite offspring was not, with a power of 36.9%. (b) Results from the final models for the reproductive success of beetles, blowflies, and mites in the Laboratory Experiment 1. For beetles, the final model used was: glmer.nb(Number of larvae ~ Mite treatment*Temperature treatment*Blowfly treatment+Carcass mass+(1|block)); for blowflies, the final model used was: glmer.nb(Number of larvae ~ Mite treatment*Temperature treatment+Carcass mass+(1|block)); and for mites, the final model used was: glmer.nb(Number of larvae ~ Blowfly treatment*Temperature treatment+Mite treatment+Carcass mass+(1|block)). All these models were sufficient to reject the null hypotheses, with the 97%, 97%, and 98.2% power, for analyses of burying beetle larvae, blowfly larvae, and mite offspring, respectively. (c) Results from the final models for the development of blowfly larvae in the Laboratory Experiment 2. For number of blowfly larvae, the final model used was: glm.nb(Number of larvae ~ Temperature treatment+Carcass mass+Blowfly egg mass); for carcass consumption rate, the final model used was: betareg(Consumption rate ~Temperature treatment+Carcass mass+Blowfly egg mass); and for development rate, the final model used was: glmer(Days ~ Temperature treatment*Developmental stage+Carcass mass+Blowfly egg mass+(1|carcass ID)). Models analyzing number of blowfly larvae and carcass consumption rate were both not sufficient to reject the null hypotheses, with 12.9% and 22.8% power, respectively, whereas the model analyzing development rate of blowfly larvae was highly sufficient, with a power of 100%. (d) Results from the final models for beetle's carcass preparation in the Laboratory Experiment 3. For number of blowfly larvae, the final model used was: glm.nb(Number of larvae ~ Temperature treatment+Carcass mass+Blowfly egg mass); and for carcass roundness, the final model used was: glm.nb(Roundness ~Temperature treatment+Carcass mass+Blowfly egg mass). Models analyzing number of blowfly larvae and carcass roundness were both sufficient to reject the null hypotheses, with 96.4% and 99.5% power, respectively.

https://cdn.elifesciences.org/articles/55649/elife-55649-supp1-v2.docx
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