coevolution of weta and fleshy fruits

Blogging on Peer-Reviewed ResearchHere's another paper on coevolution – this one a bit closer to home. It suggests a coevolutionary relationship between a weta species and the characteristics of many fleshy fruits of NZ plants (Burns, 2006).

Many plants rely on animals to disperse their seeds. Their seeds are often enclosed within fleshy fruits, which tend to be red or black, and which are found in easy-to-access parts of the plant (like the tips of twigs or branches). Burns points out that this doesn't apply to the fleshy fruits of many New Zealand plants – instead, they are often white, or pearly-coloured, and are tucked away inside a network of twigs. What's going on here?

Burns caught a young female ground weta in the alpine zone of Nelson Lakes National Park. He kept the insect in the lab for 2 days & collected its faeces, before releasing it into the wild in the place it was found. All the faecal matter contained seeds of mountain snowberry, Gaultheria depressa. This plant grows in a mat, with large fruit that are either red or white & tucked away within the plant canopy – they'd be hard for birds to find, for example. Other authors have suggested that this particular growth form might be linked to snowberry seed dispersal by lizards. Burns suggests that it could equally well be linked to coevolution with weta – but points out that, at the moment, supporting evidence is from one single observation. He suggests that the link could be tested by experiments looking at how much seed is dispersed by weta, lizards, & birds, and also at how well they do it – a fruitful topic for future researchers 🙂

Reference: K.C. Burns (2006) Weta and the evolution of fleshy fruits in New Zealand. N.Z. Journal of Ecology 30(3): 405-406

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