When is an ant not an ant? When it is a spider

Embargoed until: Publicly released: 2024-02-14 11:01

Australia; NSW

Some ant mimics and putative models. An accurate ant mimicking insect (immature Alydid sp., top left) and presumed model (Oecophylla smaragdina, bottom left). An accurate ant-mimicking spider (Myrmarachne macleayana, top right) and putative ant model (bottom right, Polyrhachis robsoni). Photographs, Jim McLean.

Some spiders are just as good at looking like ants as other insects are, according to Aussie researchers, who found both ant-mimicking spiders and ant-mimicking insects had varying abilities to copy their anty cousins. Ants are well-armed, often aggressive, distasteful, and attack in groups, which makes them unsuitable prey for many species. This also means other animals can gain an advantage by looking like ants. The researchers had thought that spiders might be limited by their body shape and would be less able to convincingly copy the ants. However, they found good and bad mimics among both spiders and insects. The authors say this suggests that imperfect copying may be offering some advantage, rather than just being limited by body shape.

Media release

From: The Royal Society

Morphological ant mimics: constrained to imperfection?

The extent to which evolutionary constraints, rather than adaptation, drive evolutionary outcomes is an open question. Imperfect mimics provide an opportunity to address this question empirically: contrary to naïve theory, imperfect mimics are abundant, and constraints have been proposed as an explanation. We compared the mimetic accuracy of ant mimicking spiders with ant mimicking insects. Since the body plans of spiders, but not insects, differ substantially from that of their ant models, we expect spiders to be constrained compared to insects. We found that spiders are able to reach similar levels of mimetic accuracy as insects, ruling out constraints as a mechanism.

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Some ant mimics and putative models

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Research The Royal Society, Web page Please link to the article in online versions of your report (the URL will go live after the embargo ends).

Journal/
conference: Biology Letters

Research:Paper

Organisation/s: Macquarie University, The University of New South Wales

Funder: This work was supported by a grant from Australian Research Council, DP170101617.

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