Help us understand mimicry!

Picture1I have written about mimicry before, describing why most mimics are imperfect and how some mimics imitate not only the appearance of other animals but also their sounds and behaviour. Now, I need your help with an ambitious experiment to test theories about the evolution of mimicry. Most people know that there are harmless animals that have yellow and black stripes to look like stinging bees and wasps. But did you know that there are many thousands of such species, all with different degrees of “bee-ness” or “waspiness”? The new experiment is designed to compare 56 harmless hoverflies with 42 wasps and bees to measure how similar they are. That’s 2,352 unique comparisons! This information will allow us to test exciting new ideas about the evolution of mimicry. There’s only one catch…

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With his beard and odd dress sense, Uncle Sam would have made a fine entomologist!

This particular experiment will use the human brain as a processing tool and the power of the crowd to generate data. It’s a bit like “Strictly Come Mimicking” (or “Mimicking with the Stars“, if you’re in the US): you just need to rate how similar you think the two insects appear out of 10. I’d appreciate it greatly if you could take some time to run through the experiment below. Don’t do it thinking that there is an end, though – there are 2,352 combinations, remember, and the images are randomly paired on each screen! You can access the experiment here:

www.mimicryexperiment.net

My goal is to reach 10 ratings of each pair of insects. That means a total of 23,520 ratings. I know this is a long shot, but that’s the aim, people! Please do share it far and wide! I’ll share regular updates on the blog as the ratings come in (however many or few there are!).

Some hoverflies look like stinging wasps and bees – some even act the part!

Picture1Background: Animals and plants can benefit by resembling other species. For example, some plants have spots that look like ants to deter herbivores, cuckoos look like hawks to frighten smaller birds from their nests, and harmless snakes have striped bodies that resemble highly venomous species. However, there are other modes of resemblance: animals and plants can smell, sound or act like another species in addition to (or instead of) having visual resemblance. However, we don’t know much about how different types of mimicry interact in the wild.

What we did: Heather Penney, a MSc student at Carleton University, collected individuals from 57 species of hoverfly. Hoverflies are famous for having some examples of very close visual mimicry of stinging wasps and bees, but in some species this mimicry is “imperfect”. It is also known that hoverflies can exhibit behaviours that are characteristic of wasps and bees, and so Heather tried to elicit these responses from each of the species that she caught. She found that only 6 out of 57 species exhibited behavioural mimicry, and that these species belonged to only two genera (i.e. they were all closely related). Furthermore, there was some evidence that only animals that looked a lot like wasps also had behavioural mimicry.

Importance: While behavioural mimicry has been described a number of times in the wild, it is rarely surveyed using such a comprehensive approach – Heather tested every species in a community so that we know that there are a range of species that do not exhibit these behaviours. Also, we show that the behaviours are constrained to relatively few high quality visual mimics which suggests that behavioural mimicry acts to enhance morphological mimicry where that morphological mimicry already exists.

This is part of a series of short lay summaries that describe the technical publications I have authored.  This paper, entitled “The relationship between morphological and behavioral mimicry in hover flies (Diptera: Syrphidae)”, was published in the journal American Naturalist in 2014. You can find this paper on the publisher’s website or for free at Figshare.

Image credit: Photos by Brent Lamborn, used with permission.

Good mimics have the costumes and the acting skills

There are lots of ways to fool an observer, and I mentioned quite a few in my post on the Cafe Scientifique talk that I gave in September. However, one aspect that I didn’t mention there was “behavioural mimicry” – where an animal acts like another animal in order to fool a potential predator or prey.  This sort of behaviour has been reported plenty of times in the field, but has never been studied in a systematic way. My collaborators over at Carleton (led by Tom Sherratt and Heather Penney, who collected the data as part of her MSc thesis work) and I have just published a paper (press release here) which provides just such an overview, and tests a few key evolutionary hypotheses along the way.Read More »

Why are there imperfect mimics?

A few colleagues and I recently had a paper published in Nature on “A comparative analysis of the evolutionary of imperfect mimicry”. Those of you fortunate to have a Nature subscription can read the paper here.  Alternatively, you can email me and I’ll send you a copy.  Unfortunately, I can’t make the paper available due to issues with copyright from Nature (see elsewhere for details of scientists’ love-hate relationship with publishers…) but I can summarise the paper here.
Read More »