Odd evolutionary outcomes: green fur, body fat, anything else?

[lflournoy]

I suspect the comments saying 'green is not an animal adaptation' contain the roots of your answer.
However, the first thing I thought of was,
Squirrels proliferate in areas which turn brown in the winter, which would make other colors, during times of winter scarcity, an evolutionary DISadvantage...

 

[BillTre]

There is a population of black squirrels in Los Gatos, California.

 

[Keith_McClary]

Biofluorescent monotremes ?

 

[cmb]

Biofluorescent monotremes ?

I think the platypus is just super fun. Not content with being a semi-aquatic duck-billed egg laying teat-less mammal with flat cornea and double-cone retina, mammal teeth, 5 X and Y chromosomes, and a body temperature of 32C, it is also venomous and can hunt blind following the electric fields from its prey.

... that it might fit my query regarding odd coloured fur in some peculiar spectrum of light is of no surprise at all! ;)

 

[Pythagorean]

I think the platypus is just super fun. Not content with being a semi-aquatic duck-billed egg laying teat-less mammal with flat cornea and double-cone retina, mammal teeth, 5 X and Y chromosomes, and a body temperature of 32C, it is also venomous and can hunt blind following the electric fields from its prey.

... that it might fit my query regarding odd coloured fur in some peculiar spectrum of light is of no surprise at all! ;)

The Lotka–Volterra models demonstrates a couple scenarios for coupled prey-predators, but one interesting scenario is:

predators die out.
prey overpopulates and overconsumes resources
prey dies out

So why do people always look for a direct advantage for the prey? Why couldn't an advantage be that predators see them more readily and keep their populations healthy in regions where overpopulation and resource scarcity would have otherwise wiped out the population?

 

[BillTre]

predators die out.
prey overpopulates and overconsumes resources
prey dies out

So why do people always look for a direct advantage for the prey? Why couldn't an advantage be that predators see them more readily and keep their populations healthy in regions where overpopulation and resource scarcity would have otherwise wiped out the population?

There would be selection against the prey that were more obvious to predators looking for prey.
This would be a short term immediate response to the different color.
The selection for the unusual color to keep a smaller more manageable population would be something that works over longer time spans.
For this kind of selection to work, the shorter term selection would have to be countered in the short term somehow.
it would require special circumstances for selection to work that way.

The general idea is that evolution flows through time by paths where each step has some adaptive advantage.
Evolution does think ahead, but sometimes situations can select for things for other reasons that can be adaptive when presented with a new situation.

It should also be pointed out in this case that the fluorescence probably doesn't negatively impact the platypus's avoidance of predators because it won't be fluorescing at night when the fluorescence could be seen.
Solar UV would excite the fluorescent molecules (in nature) only during the day when UV is present in sunlight.

The fluorescent molecules may have been selected for as a sunscreen (absorbing UV, releasing energy as a rather dim green light during the day when it will not add much to visibility), if UV damage to palatypus tissues was important.
Or it (the evolution of the fluorescent molecule) could just some random thing that evolved because there was no significant selection against it.

 

[cmb]

Not sure about all the fancy theories. I think the platypus has evolved like that just for the lulz!

 

[Pythagorean]

The selection for the unusual color to keep a smaller more manageable population would be something that works over longer time spans.
For this kind of selection to work, the shorter term selection would have to be countered in the short term somehow.
it would require special circumstances for selection to work that way.

This is the kind of interesting context I'm missing not having taken any formal genetics/evolution classes. I remember reading once in my wife's genetics book how human populations (maybe even most mammals?) are balance male/female ratios through supply and demand type pressures (paraphrasing). Fascinating stuff.

The general idea is that evolution flows through time by paths where each step has some adaptive advantage.
Evolution does think ahead, but sometimes situations can select for things for other reasons that can be adaptive when presented with anew situation.

Evolution thinks ahead? I assumed it was always selected after. Is that epigenetics from grandma?
I do also imagine cases where the genetic system "remembers" old environmental challenges that may reoccur.

 

[Drakkith]

Evolution thinks ahead?

I think Bill meant doesn't think ahead.

 

[BillTre]

Yes, thank you @Drakkith.
It should have been that evolution doesn't think ahead!

Not the kind of mistake a spell checker catches.

 

[Pythagorean]

Ah yes, agreed. It would have had to evolved to an equilibrium that was settled to over time and it would have to be dynamic rather than hard coded - sort of like how it's thought we seem to adjust insulin sensitivity for our grandchildren (this is what I thought you meant by thinking ahead - re: studies around epigenetics, starving grandparents, and obese/diabetic grandchildren). The process of evolution doesn't think ahead, but it appears to evolve systems that try to predict and prepare for the future. Sort of like having an adaptation library to choose from.

But I see how it's a less likely scenario for prey to make themselves more available to predator as a matter of resource control given the delicate conditions it would be predicated on.