Thursday, May 22, 2014

Native Species Have a Hard Time Adapting to Climate Change

Did you know that experts estimate that we could lost one-fourth of the world' species by 2050?  In fact, we're discovering species just now, like the 14 new species of dancing frogs discovered in India, that are at risk of extinction.  Polar bears might disappear in the next 100 years because of melting Arctic ice, coral reefs are really feeling rising sea temperatures, and bird migration patterns are changing.  Climate change is occurring at such a fast rate that species just can't keep up, and this may lead to drastic changes in both flora and fauna in the near future.  One concern is that seed banks, which store and conserve seeds of native and heritage species of plants, may be harboring seeds that are no longer suited for their local environment.

When species cannot adapt quickly enough to a changing climate, this is known as adaptational lag.  There is very little evidence of this phenomenon available right now, but it is predicted that this adaptational lag may be mitigated by the migration of species adapted to warmer, southern climates into the ever-warming north.  That is, these southern species may now be better suited for current and future northern climates than the native northern species.  While it may sound cool to think that we might have palm trees up in Ontario, keep in mind that we'd also likely be losing MANY of our awesome native species in the process, and that's not a good thing.

There have been very few experiments that have looked at the role of specific climate factors in shaping the fitness of local populations.  A group out of Brown University looked at adaptational lag in Arabidopsis thaliana, which naturally inhabits a broad climate space in its Eurasian habitat.

File:Arabidopsis thaliana.jpgArabidopsis is like the lab rat of the plant science world.  It has a short life cycle, a small genome, small size, and produces A LOT of teeny tiny seeds (which get EVERYWHERE when you harvest them!).  And it is really easy to make transgenic versions of these plants.  These factors make it an ideal model plant, and its use in the study of plant genetics, physiology, and biochemistry is widespread.

The authors went to seed banks and found a number of Arabidopsis populations (ecotypes) that are native to different European climates: Finland, the UK, Germany, and Spain.  The authors kept plants under different temperature, humidity, and light conditions, and measured fitness as a measure of silique (those are Arabidopsis pods) length and number.  Basically, they found that each ecotype performed best in its own climate (ie, the Spanish ecotype performed best in the Spanish climate, the German ecotype performed best in the German climate), except for the Finnish ecotype.  While the Finnish ecotype performed its best in the Finnish climate, the German ecotype outperformed it, and the English ecotype was almost just as fit.  And the Spanish ecotype was as fit as the English and German ecotypes in their respective climates.

What this essentially means is that the plants that were native to a relatively southern climate were able to thrive in a warmer northern climate, and in the case of Finland, outperform the native species.  The Finnish ecotype displayed adaptational lag to the warming climate, allowing the German ecotype to thrive.  If this occurred naturally (not in a controlled experiment), the German ecotype might have been an invasive species able to choke out the native species.

We've been seeing the effect of climate change on invasive species for a while now: species like purple loosestrife, zebra mussels, and mosquitoes carrying all kinds of viruses, are examples of this.  Invasive species can be harmful to agriculture, the environment, and public health.  Preventing the spread of invasive species at the expense of native species requires an understanding of which species pose threats to the ecosystem, how they propagate, and, once an invasive species becomes established, how to keep it from spreading.

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