Julia Boyle wearing a t-shirt with the logo for her field station, the Koffler Scientific Reserve.
Julia Boyle wearing a t-shirt with the logo for her field station, the Koffler Scientific Reserve.

Julia Boyle, a M.Sc. candidate at the University of Toronto, discusses her recent publication “Plasticity and habitat choice match color to function in an ambush bug”, big questions left to answer, as well as her journey to becoming an ecologist.

What’s your paper about?

An ambush bug waits atop the head of Queen Anne’s Lace for potential prey. Its body colour closely resembles the white colour of its chosen flower habitat. Credit: Julia Boyle
An ambush bug waits atop the head of Queen Anne’s Lace for potential prey. Its body colour closely resembles the white colour of its chosen flower habitat. Credit: Julia Boyle

            Our paper demonstrates how individuals can optimize their phenotype using a combination of adaptive plasticity and habitat choice, with tangible effects on performance. The organism we used to explore this is an ambush bug, Phymata americana, a charismatic sit-and-wait predator of flower visitors. Ambush bugs varied in colour from greenish white to golden yellow, which mirrored the predominant flower colours in their environment. However, it was unknown how ambush bugs optimized their colour to catch prey, whether it be by choosing flower habitats that best matched their colour, or plastically matching their colour to flower backgrounds. We conducted surveys of wild populations to establish phenotype-environment matching and its effects on prey capture, then performed habitat choice and plasticity (colour change) trials to test for the mechanisms underlying hypothesized patterns of habitat matching.

How is your paper new or different from other work in this area?

An ambush bug waits on the petals of a Black-Eyed Susan. Its colour is a similar yellow to the petals, increasing the likelihood it will catch unsuspecting prey. Credit: Julia Boyle
An ambush bug waits on the petals of a Black-Eyed Susan. Its colour is a similar yellow to the petals, increasing the likelihood it will catch unsuspecting prey. Credit: Julia Boyle

In this paper we incorporated a measure of performance (being found with or without prey) and could therefore link the trait to a specific function. This linking of form to function can be difficult to measure in the wild and is rarely included in similar articles. In our case, we were able to specifically link how well an ambush bug matched their background flower to how successful they were in capturing prey in a completely natural environment, then test specific mechanisms of their background matching.

While more niche, another novelty of our paper was that this was the first-time body colour plasticity has been quantified in Phymata americana. Naturalists have speculated that ambush bugs may be able to change colour for decades, and we finally have evidence to support this.

What are the big questions still to answer?

            As discussed in our paper, background matching is a very complex process that can be due to several different mechanisms, such as switching environments, adjusting the environment, or adjusting traits. Within each of these broad mechanisms exist more nuance, for example, habitat selection could be driven by a combination of imprinting, genetic preference, and/or random sampling of the environment. The relative importance of each broad and specific mechanism is still a big question in the study of background matching; well-designed experiments will be needed to disentangle each effect.

            Additionally, how organisms match form to function over a lifetime is also of interest. Many organisms have remarkably varying life-stages that each face different selection pressures, and presumably require different optimal strategies. Observing how background matching strategies change ontogenetically could provide new insight into how an organism evolved, and how traits are optimized in different ecological conditions.

            Finally, phenotypic plasticity can improve individual performance in many organisms, however it is debated if there are significant costs associated with being more plastic. Are more plastic individuals constrained by costs? How does variation in plastic ability evolve? We need more conclusive experiments of the fitness benefits versus cost of being plastic; and ambush bugs may be an excellent organism to study this in.

Where you surprised by anything when working on it?

An ambush bug looks out from the tip of a blooming goldenrod. Individuals preferred goldenrod over Queen Anne’s Lace in lab habitat choice trials. Credit: Julia Boyle
An ambush bug looks out from the tip of a blooming goldenrod. Individuals preferred goldenrod over Queen Anne’s Lace in lab habitat choice trials. Credit: Julia Boyle

Our result that ambush bugs were able to become significantly more yellow but not whiter surprised me. We hypothesize that this result is due to either physiological constraint, ontogenetic change, or weaker environmental selection for whiter ambush bugs. In comparison, one of the other main sit-and-wait ambush predators in the region are crab spiders, which can change back to a whiter colour from yellow, albeit more slowly than their transition from white to yellow. Since the two are ecologically similar I expected the same of their patterns of phenotypic plasticity, so it is interesting to compare and contrast the two species.

How did you get involved in ecology?

I was heavily inspired by my professors’ enthusiasm and research during my undergraduate degree, where I specialized in Ecology and Evolutionary Biology at the University of Toronto. I sought out the university-owned Koffler Scientific Reserve to try field work over multiple summers, which fully solidified my love of ecology and all its complexity. My time there also allowed me to collaborate with my talented co-author Denon Start to produce this paper! Now, as I work on my master’s at the University of Toronto, I continue to be enthralled by the insects, plants, and microbes that make up the world around us.

Read Julia’s paper here or the free plain language summary here.