Wednesday, 28 July 2010

Turning the Toad Tide using Genes to Geoscience (G2G)


How do you do high impact research in a world with much bigger institutions? Generate fresh ideas (bright minds) and natural advantage (Australia and its biodiversity and an organisation/group with few ‘constraints’).

This is the Genes to Geoscience (G2G) philosophy of Mark Westoby and his colleagues at Macquarie University. I’m attending a few sessions of a ‘Genes to Geoscience Outlook’ meeting over next two days. The main task is to generate ideas and then turn them into ‘specific questions that are tractable’ – i.e. is it a real research idea (Mark Westoby).

Here’s a sample of the presentations, first up this morning. It’s not about plants but the principles apply across all evolved life. Reptile and amphibian expert, Rick Shine from University of Sydney, talked on evolution as an applied science. That is, using an evolutionary perspective to answer ‘applied’ questions.

Evolution in living things, and in fact in just about anything (e.g. football codes), depends on things changing over time and the useful traits surviving (being adaptive). As an example, in engineering you can create lots of different widgets and try them out – the ones that work, get used.

We tend to not use evolutionary theory in medicine – e.g. we should sort out adaptive responses by people rather than treating symptoms. This was just thrown out as comment, but interesting to explore further and understand what it might really mean!

In conservation biology evolution has been largely ignored because evolution is seen as ‘too slow’. But things we do to manipulate the environment effect evolution (e.g. catching and eating the bigger fish).

And so to toads. Australia has lots of frog species but no native ‘toads’. Cane toad kills animals and changes ecosystems – the various connections and things that happen in a living environment.

How are the toads, and native animals, adapting (evolving)? The invasion is a ‘foot-race’ across the continent so the quickest toads (up to 100 metres a day) survive and do well on the ‘invasion front’. The ones at the front get access to more food and habitat, and breed, and so on… The rate of spread increases as faster toads evolve.

Things that eat toads don’t do so well, unless they are tolerant to the poison. Black snakes? Their range overlaps the toad range in part. In toad-invaded areas the snakes don’t eat toads while those from outside do. You can’t ‘train’ the outsiders so they have become physiologically more tolerant. This has all happened over 70 years – a relatively rapid evolutionary response.

So controls can focus on things that are easier to change, in the toad or its predators. For example concentrate toad breeding into smaller areas (by changing habitat) so that interbreeding and disease thrive. Use native frog tadpoles to compete with toads – even though they don’t eat them they seem to put them off. Find and encourage more local predators. Use toad alarm and attractant chemicals to mess with the toad life cycle.

In all cases, you need to make sure you work with something that won’t lead rapidly to evolution of a counter solution by toad (my words).

Rick Shine ended by thanking Charles Darwin for helping us to find ways to control toads. Let’s hope Rick and Charles succeed with toads, and we can adapt these ideas to controlling weedy plants.

Image: a canetoad from the website http://www.swarthmore.edu/NatSci/cpurrin1/bio97/toxins2009.htm.