Biology Natural Selection

Question

Thoroughly describe how natural selection could have selected the weird trait (feathers) in a peacock (pavo cristatus). Reference the four factors that drive the process of evolution:

(1) the potential for a species to increase in number,

(2) the genetic variation of individuals in a species due to mutation and sexual reproduction,

(3) competition for an environment's limited supply of the resources that individuals need in order to survive and reproduce,

(4) the ensuing proliferation of those organisms that are better able to survive and reproduce in that environment

Answer 1

a little background: this is not actually an open and closed topic. Darwin struggled with the explanation and another evolutionary biologist (Amotz Zahavi) has a further expanded theory. In general, let's understand the underlying concepts first.

1. What is the number one job of every single organism on this planet: The number one job is reproduction. If organisms don't reproduce their entire line dies out.
2. so breaking down Evolution: why does it happen? It happens so that organisms can increase their reproduction and their chances of reproduction. Some evolved traits help organisms better survive in their environments, and some evolved traits help organisms find better mates (mates more likely to breed children that are better suited to survive in their environments). It all boils back down to reproduction.
3. so scientifically, how do organisms evolve? This is the cool part! Through my eyes, organisms evolve through 2 related mechanisms. The first is kind of trial and error, and the second is through the winning and reinforcement of that trial and error. Certain traits in certain animals make them better off to surviving in an environment (which is important because then they can reproduce more!). For example, lets look at an island where all of the worms that birds eat used to just sit on top of the dirt floor. There were tons of worms on the floor, and the bird population shot up because they had so much food. With all of the extra birds around, the worm population started shooting down, the worms were in trouble! they either had to adapt or die. Then, suddenly, 1 worm was born that instead of sitting on top of the dirt, had a trait for sharp teeth that allowed the worm to burrow down under the dirt. That worm survived, and reproduced a bunch of baby worms that could all also dig. While all of the worms that couldn't dig slowly got eaten by the birds, the worms that could dig survived and passed on the digging skill. Back to the birds: All of the birds on this island had flat and dull beaks because all they needed to do was scoop up the worms. However, once the worms started digging under the ground and food wasn't as easily available, suddenly the birds started starving. The birds needed to adapt or die! So this evolution happened with them as well. There was suddenly 1 bird born that had a sharp and pointy beak. But how did this bird get the sharp and pointy beak? did it just wake up one morning and it was sharp and pointy? No! this is the trial and error part: When 2 adult organisms breed together and have a baby, their dna combines to formulate the baby. Normally this works really well, but sometimes there are mistakes in combining the dna and 1 letter gets miscopied. Think of the game whisper-down-the-lane. sometimes when you are whispering the word down the lane, someone hears something a little differently and the word changes just a little (sometimes the word changes a lot, but that's a different subject). This is how, suddenly, one day a bird with a sharp and pointy beak was born. Now that sharp and pointy beaked bird got all of the worms that the other birds couldn't get, and it didn't starve. That bird went on to have babies, babies that had sharp and pointy beaks as well. this is the winning and the reinforcement. The sharp and pointy beaked bird won (it got more food and lived long enough to reproduce) and its winning was reinforced because it got to reproduce children that also had sharp and pointy beaks.

So back to the peacocks. Depending on what level schooling you are, you might want to do some research on what darwin and Zahavi said.

So what role do the feathers for peacocks play? Do they help the male peacocks attract mates? Or do they make the peacocks more likely to be spotted by predators? Do the feathers make the peacock slow? Or do the large feathers help it fly better? The fact that the peacocks seem to be evolving brighter and brighter feathers might make the argument that the advantage is greater than the cost. Then again, maybe the cost isn't great enough to justify phasing the feathers out.

The interesting thing about the male peacocks is that while they have bright colors and designs ( in order to attract better mates), you also have to consider whether having such bright colors/designs and large feathers is actually a reproductive advantage. Doesn't it make them more vulnerable to predators? Or do the larger feathers help them fly better?