Monday, February 21, 2011

Climate Change and Evolution

As many of us know, there are always predator-prey interactions in any environment. Sometimes these interactions can be very complex and the predator may be very specialized to one specific type of prey. There is, for example, a very specific reliance of monarch caterpillars on the milkweed plant. The milkweed plant not only provides nourishment for the caterpillars but it also provides chemicals to the caterpillars that help make them toxic to other predators. The milkweed plants produce certain toxins to deter the caterpillars and other herbivores from eating them.

Normally there would be selection pressures on the plants so that the ones with the genetic advantage would survive and reproduce. (The genetic advantage being the plants that can produce natural insecticidal chemicals.) Due to global climate change and rising CO2 levels in the atmosphere, the natural insecticide chemicals produced by plants are being altered and the course of evolution is therefore also being changed.

In a study conducted with milkweed plants in different concentrations of atmospheric CO2, they found that chemical defenses of the plants were generally reduced. The plants began to develop other more physical defenses to help protect themselves from herbivorous insects. Because of the rising levels of carbon in the atmosphere, there may be changes in the way plants defend themselves and therefore a change in evolutionary patterns.


  1. So with this boost in natural defenses produced by plants we could see an increase in certain plant species over the next few decades because their natural predators won't be able to keep them in check. I see this as an advantage if it is found in agriculture crops because then there is less of a need for using pesticides, which are bad for the environment. However, if plants we don't particularly care for become resistant to natural predation this becomes a problem because more herbicides will be used to kill them.

  2. This study is a nice illustration that the effects of elevated CO2 on plants and the ecosystem is not easy to predict. Individual plant responses vary in terms of the amount of growth promoted or the secondary chemistry affected, and this is likely to shift ecological balances. More significantly, the changes in temperature that are predicted will have other effects. With regard to other evolutionary changes, many extinctions are predicted, which will impact the species still remaining. There are many complexities to consider.