Climate Change & Anthropocene Extinction 13: Being small is no guaranteed climate change survival strategy

If you live inside a heap of compost in someone’s backyard, your life may already feel quite miserable. But if you’re really tiny, at least you’re probably thinking your chances of surviving climate chance are –comparatively– okay.

Well, our dear little springtail –we hate to bring it to you– but science may have bad news. Sometimes it’s just not fair.

Small species do not always have survival advantage under climate change
He may not look it, but for a springtail this one (Folsomia candida) is actually quite large (>2mm). And even though he needs to eat more food to survive under climate change – his relative size still placed him at an advantage to a smaller co-existing springtail (Proisotoma minuta), that went extinct – in below petridish climate experiment. Image credit: Andy Murray.

Climate change increases species competition and thereby extinctions

We’ve learned two important things from previous climate-biodiversity research: (1) that climate change increases species competition, which in turn leads to accelerated biodiversity loss – and (2) that in a warming scenario it is usually larger species that die out first – placing smaller species in a relative advantage.

Now new research by the German Centre for Integrative Biodiversity Research (at Leipzig University) that was published in Proceedings of the Royal Society B in March 2017 confirms that indeed climate change ends peaceful coexistence of (prey) species – but when it comes to very small organisms, perhaps you don’t want to be too small.

This at least seems to go for a double community of two springtail (Colembola) species (Folsomia candida and Proisotoma minuta), that had a natural balance with a predatory mite species.

One needs to eat a lot to survive – the other gets eaten. Who would you rather be?

You may not really know springtails, but you’ve probably seen them in your life – and in any case profited from their tireless work. Springtails are small (couple millimetres in body length) insect-like arthropods with 6 legs that are somehow not considered insects. They live their lives in leaf litter and other decaying biomass, where they feed on fungi and plant material. In doing so, they are extremely useful for the creation of compost – especially because springtails tend to work in very large numbers (estimates are 100,000 individuals per square metre of ground) – and in peaceful coexistence among related springtail species.

That coexistence however is challenged when the average temperature goes up – an artificial climate change experiment has shown.

The Leipzig-based research group was not surprised that in model with two springtail species the existing balance would be disturbed – as food competition increased, while the micro-ecosystem was also under pressure from the presence of predatory mites.

They were however surprised to find out that it was the larger of the two springtail species that coped best – even though this species depended on a larger caloric intake for its survival, a real problem as food scarcity can become a limiting factor under species competition and the metabolism of both species increases as the average temperature goes up.

This also goes for the predatory mites though, that also needed to eat more as climate change increased their metabolism. And apparently the smaller of the two prey species, which was thought to be more adaptive, was in fact less.

© Rolf Schuttenhelm |

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