Wing-pattern-specific effects of experience on mating behavior in Heliconius melpomene butterflies
Summary (2 min read)
Introduction
- Many of the behaviors and decisions that an animal makes are affected by its observations and capacity to learn.
- Learning in animals is often complex and is likely the result of the social dynamics and settings of a species (Coussi-Korbel and Fragaszy, 1995) .
- Previous studies show that mimetic coloration in this species is important in choosing mates, and that these butterflies show assortative mating when choosing between their own and a different, closely related species (Heliconius cydno) (Jiggins et al., 2001) .
- 3) If males are not able to learn, then courting was predicted to occur at random in both experienced and naïve males.
Study species and husbandry
- Heliconius melpomene is a widespread neotropical butterfly found in Central and South America (Brower, 1994; Sheppard et al., 1985) .
- The species is well known for its high diversity in color patterns, which play an important role in speciation (Jiggins et al., 2004) .
- Caterpillars from the colony were given Passiflora plants ad libitum, and prior to pupation, plants containing caterpillars were removed from the breeding cages and moved to a separate 60.96 x 60.96 x 142.24 cm cage until butterfly emergence from pupa.
- The greenhouse was lit by Sun Blaze T5 high output 120-volt fluorescent light fixtures (containing UV wavelengths), in addition to natural sunlight, and the presence of UV light in the greenhouse was confirmed using an Ocean Optics Jaz spectrometer.
- Males were placed into sex-and phenotype-specific cages, so they were isolated from both females and other wing patterns prior to behavioral assays.
Observational Experiment Time of Day Selection
- To determine the time of day when the butterflies were the most active, the authors observed butterflies in colony cages for three consecutive days, between 6:00 am and 8:00 pm.
- Point counts were conducted every thirty minutes, where behaviors (flight, walk, flutter, abdomen lift, bask [defined by resting with wings held in open position], rest [defined by resting with wings held in closed position], antennae wiggle, court, and copulate) were recorded for each cage, followed by two ten-minute focal watches of one male and one female butterfly selected at random.
- Based on observations, the authors determined that butterflies were most active between the hours of 10:00 am to 2:00 pm.
Behavioral Watches
- All behavioral watches took place between 10:00 am and 2:00 pm, the time of peak H. melpomene activity in their greenhouse.
- Each watch consisted of a male aged ten or twelve days old, and a female between three and five days old.
- To test whether males courted females with matching wing patterns faster than they courted conspecific females with dissimilar wing patterns, the authors tested latency to courtship and presence of courtship of naïve, 12-day-old H.m. malleti and H.m. rosina males matched with either females of their own phenotype or females of different phenotypes.
- Afterward, the female was removed, and the male was returned to the all-male, phenotype-specific cage.
- The number of incidents of each type of behavior (flight, walk, flutter, abdomen lift, bask (wings open), rest (wings closed), antenna wiggle, sitting near, and court) were recorded.
Statistical Analyses
- All statistical analyses were performed in JMP v. 14 (SAS Institute, Cary, NC, U.S.A.).
- The authors assessed whether latency to court was influenced by male experience or female wing pattern (similar or different from the male's) using a GLM with male experience and female wing pattern as factors, as well as an interaction term.
- To test whether female behavior during a male's first experience with a female had an effect on the observed courtship behavior in later interactions with females, the authors analyzed all behavioral data collected on day 10 watches (N=51 watches with behavioral data) and examined whether any of these behaviors were predictive of male courting on day 12.
- To do this the authors ran a principal components analysis on all the female behaviors and then ran logistic regression models on the first three principal components.
Ethical Note
- All H. melpomene butterflies were kept under laboratory conditions as defined by U.S. Department of Agriculture, Animal and Plant Health Inspection Service permit P526P-17-00343.
- Before being used in behavioral watches all butterflies were maintained in cages in a climatecontrolled setting in conditions similar to those of their native habitat, and cages were inspected daily for ample food and appropriate conditions.
Discussion
- The authors results show that male H. melpomene butterflies change their mating behavior in response to a social experience.
- The negative effect of the pre-mating social exposure, and the wing-pattern-specific response to this pre-mating social exposure, were unexpected.
- These males are then tested repeatedly, and past experience is often not accounted for when male preference is assessed, assuming that past experience does not inform present courting decisions.
- It also highlights the importance of checking for both positive and negative valence when testing the presence of learning.
Conclusion
- Here the authors show that male H. melpomene butterflies use past social experience to inform current mating behavior.
- This response is lineage (wing pattern) specific, and coincides with lineagespecific differences in male assortative preference.
- The authors findings strongly suggest that there are lineage-specific selective forces acting on cognitive function in Heliconius butterflies.
- Lineage-specific effect of experience on male courtship.
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References
83 citations
"Wing-pattern-specific effects of ex..." refers background in this paper
...…the capacity to learn can be energetically costly, and is often associated with fitness trade-offs, such as reduced fecundity (Kotrschal et al., 2013; Snell-Rood et al., 2011), reduced lifespan (Burger et al., 2008; Kotrschal et al., 2019), or extended development time (Kolss and Kawecki, 2008)....
[...]
73 citations
"Wing-pattern-specific effects of ex..." refers background in this paper
...Female Teleogryllus oceanicus crickets modify their mate preferences after hearing attractive male songs (Bailey and Zuk, 2009), and female Bicyclus anynana butterflies learn preferences for enhanced male ornaments (Westerman et al., 2012)....
[...]
...They have large brains (Montgomery et al., 2016) and are both physically larger, and longer lived than the butterfly Bicyclus anynana, which also uses past experience to inform current mating behavior (Dion et al., 2020; Westerman et al., 2012; Westerman et al., 2014)....
[...]
72 citations
71 citations
"Wing-pattern-specific effects of ex..." refers background in this paper
...They have large brains (Montgomery et al., 2016) and are both physically larger, and longer lived than the butterfly Bicyclus anynana, which also uses past experience to inform current mating behavior (Dion et al., 2020; Westerman et al., 2012; Westerman et al., 2014)....
[...]
71 citations
"Wing-pattern-specific effects of ex..." refers background in this paper
...Female Teleogryllus oceanicus crickets modify their mate preferences after hearing attractive male songs (Bailey and Zuk, 2009), and female Bicyclus anynana butterflies learn preferences for enhanced male ornaments (Westerman et al., 2012)....
[...]