Monday 29 June 2020

Ceci n'est pas un crapaud

Proceratophrys boiei is not a leaf
Science is one way of making sense of the world. Wordsworth had a view on how a crowd, a host of daffodils impacted the human eye to delight the soul. Wordsworth's distillation has improved my awareness and appreciation of the wonders of the ordinary.  One of the making sense tasks of science is classification: it helps to find commonality among the different ways of making a living on this planet. I was reflecting recently on Dry Heath and the extent to which this biome exists outside of text-books. My tentative conclusion is that biomes are real conglomerations of interacting species which can help us predict what will be present in newly investigated landscapes. Any exceptions may be treasured because they will extend our understanding but the exceptional baby shouldn't require us to deny that the biome bathwater is wet.

Cycloramphus lithomimeticus is not a wet stone
Classification can be applied, not only to ecosystems, but also to the species of which they are comprised. In 1975 I concluded that it was not useful to base your classification on a single obvious attribute - we'll put all the flyers [bats, beetles, birds, butterflies] in this bin; all the sedentaries there; whales and sharks in that tank - not least because some birds swim better than they fly; and barnacles, birches and Bob-the-sofas make a very heterogenous group of sitters. Concentration on obvious features for diagnosis and classification has led us up the garden path a good few times and invisible DNA sequences have really helped to resolve who is related to whom.

Scythrophrys sawayae is not dried leaf-litter
Today, I am compelling you-eeeeuw! to look at the extraordinary lengths to which some frogs have gone to avoid being eaten. Unless you believe in a very diligent and slightly unhinged special creator for each of these solutions to the problem of predation, then the rest of us turn to the incremental changes wrought by evolution to explain both the differences and the similarities. You don't have to be a perfect mimic of a stick to survive long enough to get in a bonk or two and leave similar-looking offspring to posterity; you just need to look a little less froggy and more nothing to see here leafy than your neighbour. It's like you should always distress your bike a little and try to lock it near to a really swish expensive looking model belonging to someone else. Frogs need to keep still too, and be lucky, but looking a bit leafy may get their gametes over the line. For me the interesting thing is that these species are as different from each other as can be while still being mustered into Order Anura.
Cycloramphus lithomimeticus is in the family Cycloramphidae
Proceratophrys boiei is in the family Odontophrynidae
Scythrophrys sawayae is in the family Leptodactylidae
Odontophrynidae used to be lumped in with Leptodactylidae until 2006 DNA data suggested that they were a) a clade - a group of species descended from a common ancestor b)  longtime separated from the Leptos. Thus the evolutionary strategy of trying to look like something else has been re-invented multiple times . . . because it works.

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