[ExI] evolutionary puzzle

[John Clark]

On Sun, Oct 8, 2017 at 12:43 PM, spike <spike66 at att.net> wrote:



> ​> ​
>  how would the instinct to not mess with the skunk get encoded into the
> genes?  The skunk’s non-lethal defense would not seriously impact the
> unwise dog’s reproductive capacity (temporary delay only.)
>
> ​
The lifetime of all animals is temporary. For several hours after an animal
has been sprayed by a skunk its going to be visually blind, have no sense
of smell and is going to be stumbling around distracted by pain; during
that time its going to be more vulnerable to predators.
​ ​
I don't know exactly how much that will decrease it's chances of passing
along its
​ ​
genes
​ ​
into the next generation but it would certainly be greater than zero and
over thousands of generations it would add up, animals that didn't like the
look of skunks would have an advantage over animals that had no such
aversion.

Of course this couldn't work if a predator didn't have a quick and easy way
to tell a skunk from a squirrel or some other small harmless animal, and
that's why
​the​
 skunk evolved its distinctive white stripe. That's also why extremely
poisonous small frogs and insects have super bright day-glow colors, but
its a constant arms race, some species don't bother making the poison and
would be good to eat but they mimic the bright coloration of the poisonous
animal, so that animal must evolve a even more conspicuous marker.
​

It
​ ​
reminds me a bit of sexual selection. Why do male peacocks have such a
ridiculously large tail when a cumbersome thing
​like that makes them very poor flyers and ​
must greatly reduce
​their​
 chances of having a long life? Because female peacocks like large tails.
​Why do females like long tails? Because to
mate with the healthiest males
​ they needed a marker that could quickly let them tell a healthy male from
a unhealthy one, and long ago Evolution must have decided large tails were
a pretty good rule of thumb for that. But Evolution is not perfect and
things can get out of hand.

In the population there is going to be genes for producing tails of various
sizes and genes for liking tails of various sizes​
​,​
birds with midsize tail
​s​
would make the best flyers and have the longest life but from peacock's
genes point of view this was obviously not the most important
consideration. So females who have genes for liking the long
​est​
tails would mate with males with genes for making the longest tails
producing offspring that have both types of genes. This will lead to a
disastrous positive feedback loop ending only when the advantage of
superior flight performance
​and longer life ​
of birds with midsize
​tails ​
outweighs the greater difficulty
​ in​
finding a mate.

 John K Clark
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