Posted on 04/26/2006 8:10:51 AM PDT by orionblamblam
"IT'S the wild west of evolution and ecology," says Joel Brown, an ecologist at the University of Illinois at Chicago. Evolution is operating with a vengeance in the urban environment as animals struggle to adapt to novel conditions and cope with "evolutionary illusions".
An animal is said to be in an evolutionary illusion or trap when it does something it has evolved to do, but at the wrong time or in the wrong place. The concept may help explain why so many squirrels get squashed on city streets, says Brown. For millions of years, squirrels have evolved to cross open spaces as quickly as possible, without wasting time watching for predators that they would not be able to escape anyway. "Ordinarily, that was a very sensible thing to do," he says. "But as an urban squirrel crossing four lanes of traffic, that's a bad idea."
Though ecologists used to dismiss urban areas as unworthy of study, they have recently begun to realise that cities provide an ideal theatre in which to see behaviour evolving at a pace rarely seen in the wild. City environments tend to be less variable than the countryside. Urban heat islands mean that insects can be active longer or throughout the year, and human activity provides urban wildlife with more stable, predictable sources of food and water.
Surprisingly, this too can set an evolutionary trap, as an abundance of food is not necessarily a good thing because it may give animals the wrong signal. For example, the numerous bird feeders in Florida suburbs allow Florida scrub jays to live a well-fed and relatively stress-free life. This easy living has a cost, says Reed Bowman, a behavioural ecologist at the Archbold Biological Station in Lake Placid, Florida. By mimicking an unusually early and productive spring, the artificial abundance fools the suburban birds into breeding several weeks earlier than country birds, and laying larger clutches.
And here's the trap: the nuts and other plant foods that fatten the parents are unsuitable for nestlings, which need the more digestible protein provided by insect larvae that will not emerge until later in spring. As a result, suburban nestlings are more likely to starve or be stunted, Bowman has found. He will report his results next week at a meeting on urban birds at the American Museum of Natural History in New York.
The city's bright lights may also set a trap for animals. Sea turtles that hatch on the beach usually head for the safety the sea, which in the wild is always brighter than the land. Now they may head inland towards lights from beachfront developments, where they are unlikely to survive. Night-migrating songbirds may fly into brightly lit buildings and radio towers, leading to deaths sometimes numbering in the tens of thousands.
Challenges of this sort make cities an ideal laboratory for evolutionary biologists to watch adaptation happening before their eyes.
In 2003, for example, Hans Slabbekoorn of Leiden University in the Netherlands showed that urban great tits sing at a higher pitch than their country cousins so that their songs stand out better against the city noise, which tends to be at lower frequency. Slabbekoorn is now doing further experiments to see whether individual tits can learn this response.
"Most of these species have just begun to adapt to human environments," Brown says. "It's a cool natural experiment."
I used to buy coffee at Joe's Diner. Then it closed and they opened a Starbuck's. Now I buy coffee at Starbucks. EVOLUTION!!!
Speaking from Springfield, Virginia, where the streets were recently paved with fur, all I can say is "bring 'em on".
What did you think evolution is?
> animal adaptation = evolution?
Over time, yup.
Ping!
Whoops, I pinged the wrong patriot.
That explains much about the difference between Top 40 and CW music.
"An animal is said to be in an evolutionary illusion or trap when it does something it has evolved to do, but at the wrong time or in the wrong place."
How can there be a 'wrong' time or 'wrong' place in evolution? Where did that notion come from?
Cordially,
But I guess eating corn when you can't find wheat is Evolution.
One would almost think that the definition of Evolution was being "defined down" so as to seem utterly non-controversial.
Microevolution vs macroevolution.
Call me when a new species evolves in the middle of a city.
They mean the response is adaptive for the previous situation the animals lived in, but in the new situation it's a maladaptive response.
I tried the image search on Google, but I didn't get any pictures of birds.
Insert Dolly Parton joke here...
Biological evolution may be slight or substantial; it embraces everything from slight changes in the proportion of different alleles within a population (such as those determining blood types) to the successive alterations that led from the earliest protoorganism to snails, bees, giraffes, and dandelions."
- Douglas J. Futuyma in Evolutionary Biology, Sinauer Associates 1986
I'm guessing, for one reason or another, we'll stop squishing squirrels before they are forced to become another species.
Still. It would be something to see one species become a different species.
The Mariah Carey effect.
Nope. Evolution requires changes to the genotype, not behaviour or the phenotype.
There is a fundamental difference between adaptation and evolution.
Acquired traits or behaviours are not inherited. e.g., You can cut off the tails of every adult rat in a population, and all the offspring will be born with tails, unless there is a developmental error or gentic change.
Also, just because the parents wish their young could eat nuts, does not mean they will produce offspring that can survive on nuts instead of grubs
On the topic of "evolution in the urban lab", here in northern Illinois the blue jay numbers are coming back after being decimated by west Nile virus (I saw almost none in 2003 or 2004 but now they're plentiful again). It seems to me the blue jays I see now have evolved significantly and are shorter and stockier than I remember and they also have a much lower pitched call.
Has anybody else noticed this or is it perhaps just a local variation?
quote "urban great tits sing at a higher pitch than their country cousins"
*snicker*
Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.