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Why is an elaborate system for keeping populations in check supposed to be “evolutionary chaos”?


The caterpillar-wasp-virus predation system is complex but there is no reason to think it is chaos:

One of the groups involved is the Lepidoptera, the butterflies and moths. They are seemingly the victims in this story because, like any other species, they can be infected by viruses. Many of these viral infections can be fatal, although some kill the animal quickly, and others take their time. Since they often strike during the larval/caterpillar stages, the viruses need other hosts to transfer the viruses to other victims.

Some of the species that perform this transport service are parasitic wasps, which have their own designs on the butterflies. The wasps lay eggs on caterpillars, and the larvae that emerge simply start eating the caterpillar while it’s still alive.

This situation sets up some complicated competitions. For example, some viruses may depend on the wasp to spread to new hosts but, once there, start competing with the wasps for the cells of the hapless caterpillar. The caterpillars are not entirely defenseless, though, and some are able to mount an immune response to the virus. Some strains also appear to be able to resist the invasion by wasp larvae. However, viruses often encode proteins that tamp down on the immune response to their benefit, which would also benefit their competition for cells.

John Timmer, “Evolutionary chaos as butterflies, wasps, and viruses have a three-way war” at Ars Technica July 30, 2021

It’s just more complex than humans might have expected it to be and perhaps more complex than we could design.

The paper is closed access.


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