Seminar 2nd March 2010 noon B62 (Boldrewood) Seminar Room 3
Lessons from nature – how animals avoid the Tragedy of the Commons
Dr Patrick Doncaster
University of Southampton
- Categories
- Ecology, Evolution, Game Theory
- Submitter
- Richard Edwards
The Tragedy of the Commons is the environmental ruin that results from free access to a self-renewing resource. Tragedy ensues for all exploiters when each new grab of the resource for personal gain carries a cost in stock depletion that is equally partitioned amongst everyone. In the free market, stocks can and do collapse before the personal cost of exploitation has risen to match the personal gain. The term was coined by Garrett Hardin 40 years ago (Science 1968), and it has come to encapsulate all that is wrong with humankind’s pillaging of the world’s renewable resources, be they utilitarian such as fisheries and forestry or ecosystem services such as water supply and air quality. The solution is to control access. As Hardin put it 30 years on (Science 1998): I might want to rob a bank, but I don’t want everyone else to rob banks too. Humans have laws to prevent the dilution of personal cost. Likewise, many animals have territories to regulate access to limiting resources. Of those that don’t, most find less to eat when food is less abundant. Gastropod grazers present an interesting exception to these types of self-regulation, being inherently susceptible to the Tragedy of the Commons because grazing efficiency does not decline with food abundance. Here I show how the grazing apparatus of limpets has morphological features that prevent over-exploitation, specifically in the arrangement of the radula teeth. I present initial data suggesting that a gappy tooth structure may avert the Tragedy of the Commons. If it serves this adaptive function, it should be robust to invasion by any more efficient grazing apparatus. I identify conditions under which grazing inefficiencies may be evolutionarily stable, thereby ruling out alternative explanations for gappy teeth.