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    Is Evolution Fast Enough?
    By ... ... | June 23rd 2011 09:05 AM | 7 comments | Print | E-mail | Track Comments
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    The world is changing. Climate change, deforestation, and much more, are all having an impact on our litlle planet. A question that follows this statement quite naturally, is 'Will the earth's organisms be able to adapt to the changing circumstances?'

    Well, probably, some will, given enough time. But that might be a problem.

    The world is changing fast. So the question should really be 'Will the earth's organisms be able to adapt to the changing circumstances fast enough?' 

    To test this, researchers at McGill University decided to track the fate of more than 2000 populations of yeast (more specifically baker's yeast, or Saccharomyces cerevisiae). Why yeast? Two reasons: 1) it's a well-established model organism in biological research, so a lot is known about its genetic makeup, and 2) it reproduces in a matter of hours.



    Figure 1: Saccharomyces cerevisiae, or baker's yeast (Source: Wikimedia Commons, Masur)

    By using a robot, they were able to monitor and manipulate the environmental stress (in the form of salt) of the populations to varying degrees. This allowed them to study evolutionary rescue, which is the ability of a population to adapt fast enough to changing circumstances in order to survive. 

    They found that there were three important factors in their experiment, affecting the likelihood of evolutionary rescue.

    1) The severity and rate of change in the environment. The more gradual the change, the better.

    2) Prior exposure to the stressor (in this case, salt).

    3) The degree of isolation from other populations. Contact with populations that had already experienced environmental change increased the survival of another population during a rapid and severe perturbation.

    After 50 - 100 generations, adaptations to the new circumstances could be noticed, which is surprisingly fast. Doing a similar test on mammals would be interesting, but would require a lot more time. Probably too much time given the current rate of environmental change.

    The next best thing is to develop a model and extrapolate from it. 

    Reference

    Bell, G. and Gonzalez, A. (2011). Adaptation and Evolutionary Rescue in Metapopulations Experiencing Environmental Deterioration. Science. 332(6035), pp. 1327 - 1330. doi:10.1126/science.1203105.

    Comments

    Gerhard Adam
    Will the earth's organisms be able to adapt to the changing circumstances?
    I think you have to consider whether it is even necessary?  Climate change isn't quite as relevant if a species can migrate to a different climate zone.  I would suspect that climate change would only be an incidental factor if habitat isn't compromised (such as the case for polar bears).
    Gerhard Adam | 06/24/11 | 07:20 AM
    G.D.W.
    Some organisms will indeed be able to migrate. But others won't. And those that can won't necessarily find a suitable habitat, since there are other aspects of the environment that determine its suitability (presence of other organisms, or food items, and so on). Besides, even if only a few species succumb, this can have a destabilizing effect on the entire food web, depending on the species. Habitat suitability isn't the only thing that is influenced by climate change either. For example, the periodicity of many organisms changes, birds being born before the caterpillars come out, leaving the young birds without food, plants blooming before their pollinators emerge, and so on. 
    The complex and intertwined potential effects of climate change do, in my humble opinion, pose a challenge to many organisms, and some (as you point out perhaps those with great migratory abilities) might be able to deal with it more easily than others.

    ... ... | 06/24/11 | 09:46 AM
    Gerhard Adam
    I think the overwhelming majority of organisms will have little or no problem with climate change (primarily invertebrates).  With the daily temperature ranges to which they must cope, an overall change in climate isn't likely to have much effect (also with their relatively short lifespans they can "evolve" more quickly).  It becomes more problematic with the vertebrates, because they are much more susceptible to disruption of their habitat, but that's something that is an ongoing problem whereas climate change is relatively recent.  So, my point is that normal human population growth is a significantly greater risk to them than climate change is (except where such change initiates a migration that compromises their habitat even more).

    As far as shifts in feeding patterns, those are definitely selection criteria and will result in rapid adaptation or likely extinction.
    Gerhard Adam | 06/24/11 | 10:14 AM
    I agree with Gerhard.  Loss of habitat and resources is -- and will continue to be-- the driving force behind adaptation or extinction of vertebrates (human beings included).  Of course, climate change will effect habitat and resource abundance, but I think our dependence on fossil fuels as a primary energy source will  effect the population of the human animal well before climate change does.  The gift of fossil fuels has allowed our population to grow exponentially, and without oil as a resource to support our population's needs, the number of human beings will need to decrease.  I guess the question in regards to the human animal is... will our technology "evolve" fast enough to save us?  Or will we be subject to the same drop in population as any other animal that has munched through its necessary resources?  
    jshugart (not verified) | 06/24/11 | 15:06 PM
    G.D.W.
    Hmm... It seems that the focus here has shifted to climate change a little too much. Notice that I wrote "Climate change, deforestation, and much more, are all having an impact on our little planet.". So, I do not mean that climate change is the only (or perhaps even most important?) factor driving adaptation or extinction. The point I was trying to make is that human impact, in all its guises, is rapidly changing the environment on earth. Further, it seems to me that separating the effects of climate change from those of, say, habitat degradation, or any other large environmental change caused by humans, is very difficult as they all appear to influence each other.

    "I guess the question in regards to the human animal is... will our technology "evolve" fast enough to save us?  Or will we be subject to the same drop in population as any other animal that has munched through its necessary resources?"

    That's indeed an important and interesting question. We'll see, I guess...
    ... ... | 06/25/11 | 05:21 AM
    Next to the birds, human animals are most apt to migration. so they won't go extinct, in an evolutionary sense. Of our necessary resources, fossil carbon is the most threatened one, and as a consequence, commodity food. Human individuals will have a hard time, as they had most of history, but I see no reason why the human species will go extinct.

    paulvs (not verified) | 06/26/11 | 01:32 AM
    Gerhard Adam
    ...human animals are most apt to migration. so they won't go extinct, in an evolutionary sense.
    I would agree that human extinction isn't likely, but equally human migration is even less likely.  Humans have divided the planet up with too many barriers to such a response, in addition to which our absolute dependence on an elaborate infrastructure has made our large-scale survival open to question.  In other words, while extinction isn't likely that doesn't mean that millions, if not billions of people couldn't die if the "wrong" events occur for which we are unprepared. 
    Gerhard Adam | 06/26/11 | 12:40 PM