Budikka666 wrote:

"The research focused on great tits in ten major European cities,
including London, Paris, Amsterdam and Prague."

Now I have your attention, let us continue: "Birds living in cities are
performing a type of 'avian rap' while their rural counterparts are
sticking to more traditional sounds, a study shows. Dutch researchers
found that urban species of birds sing short, fast songs rather than
the slower melodies of countryside birds. City birds also sing at a
higher pitch and will try out different song types. Experts said city
birds have adapted to counter background noise and increase their
chances of finding a mate."
http://news.bbc.co.uk/2/hi/uk_news/6209498.stm

One way a single species can embark upon divergence into two separate
species (macroevolution) is by a subset of the species distinguishing
itself from the rest of its "kind" with a particular characteristic.
It can be done with a physical attribute such as color, or by the size
or shape of an appendage like a beak or a tail, or it can be by the way
it attracts mates.

Subject to louder noises in urban envronments, the great tit evolved a
different song - one that helped it find mates more easily. Over time,
a simple change like that can reproductively isolate a group from the
rest of its species.

Eventually, the isolation can be such that even if some of these birds
returned to the forest, they would not breed with native forest birds
of their own species because they would not "recognize" the mating song
for what it was. They would breed only among others of their kind who
had the new song.

This reproductive isolation means that any genetic changes accumlated
in the ex city-dwellers would not be spread throughout the species,
only throughout those with the new song. So we would have two distinct
sub-species where there had been only one species.

The accumulation of changes over several generations in each of the
sub-species would eventually lead to the point where they could no
longer interbreed even if they tried. They would become completely
separate species.

An example illustrating such reproductive isolation is the Larus gull
which can be found in a varying chain all around the arctic circle.
You can read about them here:
http://en.wikipedia.org/wiki/Ring_species

This is the origin of species - or at least an example of it. Once a
group of organisms speciates, the long road to a new "kind" has begun.
Something akin to a rat spreads its range. A sub-species of it takes
to the trees. A sub-species of that one starts eating fruit. A
sub-species shortens its nose. A sub-species of that one grows larger.
A sub-species loses its tail. A sub-species of that one starts eating
meat. A sub-species of that enlarges its brain. A sub-species comes
down from the trees. A sub-species of that one becomes human.

All of it in small steps without any dinosaur ever laying an egg and
having a bird fly out of it

It's all written in your genes.

Budikka

That's been around for quite a while.

It sucked me in the first time, too.

Damn you Red Baron.