This thread is a tangent from another coffee house conversation about climate change (http://forum.beemaster.com/index.php/topic,36708.0.html
What is evolution? Evolution is nothing more than a change in the genetics of a population over time. That’s it. Here are some examples that are easy to wrap your head around:
- When beeks talk about selecting for hygienic behavior to control varroa, they are talking about evolution. Essentially, those colonies that don’t show hygienic behavior die or are not selected for splits, while those that are hygienic survive and get picked for splits. As a result, over time, the genes controlling hygienic behavior become more common in the region’s bee population, and that change in the genetics of the population over time is evolution. As I understand it, a similar thing happened with tracheal mites: no effective treatment was found, those colonies without any resistance died off, those with some resistance survived and reproduced, the genetic makeup of the population was changed, and the bees evolved.
- Even if you believe that god created the earth and all species in their current form, you have to admit that most breeds of dog were derived recently (in the last few thousand years) through selective breeding by man. We started with wolves and kept the offspring with the traits we liked, including lack of aggression and pup-like anatomical features. After thousands of years of selective breeding by man, various populations were selectively bred for different behaviors and forms, resulting today in all the different breeds. The characteristics of each breed are genetic, and so the genetics of the population has changed over time…evolution. This same thing happened to countless other species domesticated by man.
- Many of the commercial crops grown in the US (and around the world) today are ‘genetically modified’ for herbicide resistance. Originally, the process started by selection; companies like Monsanto would expose large numbers of crop plants to low levels of herbicide, look for survivors, and selectively breed those as new strains of ‘Round-up Ready’ crops. Change in population genetics over time. Now they simply insert the genes directly into new species! But still, it is a change in population genetics over time. Since Monsanto bought Beelogics, there has been speculation that they are going to derive a new strain of pesticide-resistant bees, but that remains to be seen.
Those are all cases of artificial selection by humans, but of course selection happens in nature too. Usually it is a very slow process that is difficult to observe, but here are a couple easy examples.
- Ever wonder why you get a mumps shot once (maybe 1 booster) but have to get a flu shot every year? It’s because the flu mutates with a very high frequency rate, so much that it is SO different from one year to the next that your body’s immune system doesn’t recognize it as the same flu you had last year. Mutations are genetic, and the changes in the flu’s gene frequencies from year to year are…evolution.
- When industrialization turned the bark of English trees from light to dark, predators easily picked off the light-colored peppered moths that used to predominate because they were camouflaged. The genes for dark coloration, previously rare in the population, suddenly became favored and more common.
That’s it. Evolution is just a change in the frequency of genes in a population over time. I don’t think anyone would debate that this can and does happen; you can directly observe this, you can do it yourself in the lab or on the farm, it is pretty straightforward. Given that gene frequencies DO change, it is not a big leap to think that over time the changes can become SO BIG that a population could become different enough from others to be a NEW SPECIES. I say it’s not a big leap, but I think that’s where most people struggle with evolution. But making a new species can also be recreated by anyone in the lab, a conversation for another time…