High Speed Evolution

Taco Cowboy writes: Normally, the term "evolution" implicitly refers to super-long time frames. However, in the case of lizards on Florida islands, evolution seems to have shifted into a higher gear. Researchers have documented noticeable changes in a native species over a period of just 15 years, after an invading species altered their behavior (abstract). "After contact with the invasive species, the native lizards began perching higher in trees, and, generation after generation, their feet evolved to become better at gripping the thinner, smoother branches found higher up. The change occurred at an astonishing pace: Within a few months, native lizards had begun shifting to higher perches, and over the course of 15 years and 20 generations, their toe pads had become larger, with more sticky scales on their feet.

'We did predict that we'd see a change, but the degree and quickness with which they evolved was surprising,' said Yoel Stuart, a postdoctoral researcher in the Department of Integrative Biology at The University of Texas at Austin and lead author of the study... 'To put this shift in perspective, if human height were evolving as fast as these lizards' toes, the height of an average American man would increase from about 5 foot 9 inches today to about 6 foot 4 inches within 20 generations — an increase that would make the average U.S. male the height of an NBA shooting guard,' said Stuart."

Comments

Well known,

[140Mandak262Jamuna]

Speed of evolution should be measured in generations, not years. Species that produce vast quantities of off spring will evolve faster and adapt better. There is nothing unusual or unknown about it. The mosquitoes inside the New York subways are a different species than the ones above ground. The speciation completed very quickly.

The "ring species" are basically speciation events in progress. All it takes is one catastrophe, a disease or volcanic eruption or an invasive predator species introduction, that interrupts one of the breeding in one of the islands, and there will be two species. And this is what most anti-evolution folks don't get. No, a chimpanzee did not suddenly gave birth to a human. Population of the ancestor species split into two, and one evolved to become human and the other became chimpanzee. And the split need not be geographic. Changes in mate preferences, internal body temperature, food preferences, etc can lead to breeding isolation that could lead to speciation.

Still it is nice to see evidence being presented in a species much higher than mosquitoes.

Re:20 generations

[minstrelmike]

The average height of post-war (WWII) Japanese was 2 inches taller than the previous generation. and that was due merely to the better availability of food--an environmental factor--but probably not anything to do with evolution per se.

As stated in another post, if you kill off the shortest 1/3 of the population, the average height immediately goes up.
Similarly, if the small-footed lizards drop off the trees and can't find enough food, the average foot-size immediately increases in the population independent of evolution occurring. Evolution is 2-step process. The environmental advantage or disadvantage occurs during the individual lives of each member of the species. The passing of genes to the next generation is a separate process that still reshuffles the genes via sex relentlessly regardless of environment. That's what makes it hard to determine when evolution via genes is occurring vs purely environmental factors winnowing a current population. The new population of lizards still produces some amount of small-footed ones due to sexual mixing of genes--and if the environment changes to reward smaller feet, the population will again change quickly.

Re:Is that unreasonable?

[AthanasiusKircher]

Is that unreasonable? If there were evolutionary pressure (ie, short people kept being killed before reproducing), and tall people got multiple mates, I could see this change happening within twenty generations.

Interestingly, we have had a MUCH faster increase in height in the past couple centuries, probably mostly due to improvements in living conditions, food supply and nutrition, and medical advances.

According to this recent study, for example, European men have gained approximately 4 inches in height in 100 years, i.e., about 4 or 5 generations.

So, it probably doesn't even require significant genetic changes to produce such a shift. I once read somewhere that n the early 1800s, the average height differential between upper-class and lower-class Englishmen was something like 7 or 8 inches (i.e., rich men were something like 8 inches taller than poor men).

Farm

[pubwvj]

We see this on the farm. Nature guides the hand of evolution in the wild through selective adaptive pressures. On the farm it is the hand of man, sometimes, but the same thing. We use selective pressure to improve our livestock. In just the past slightly more than a decade we have made significant evolutionary changes to our pigs. They're a particularly nice animal to work with for genetic selection because they reproduce fast (up to 3 litters a year) with very large litters (8 to 21 piglets per litter) with rapid growth (6 months to market, 9 months to breed) so we can turn over generations quickly.