i need help on biology questions!!! (natural selection) please help!?

Question

we did a lab in class with simulating natural selection and we had to do this activity where u choose random pieces of colored squares based on the ones u see first on a really colorful piece of cloth. we did it until 10 were left. now i have these questions for hw which i dont understand..

"what represents the selection pressure in this game?

what does that mean?


"what is the adaptation mechanism of the prey?"

what does that mean?

and does one color eventualy become dominant? why is that?

Answer 1

the selective pressure would be you, the chooser, as you are the one determining with squares 'live' and which ones 'die' based on their traits.

the adaption mech of the squares is not so much an adaption, as it may be with natural selection, but more of one might call a survival of the fittest, as I'm sure youve heard. the blocks that don't get picked (e.g. squares that are difficult to spot) continue to live, and should squares decide to start breeding, only the surviving squares will have baby squares with their squarish traits (4 90degree corners, 4 sides of equal length, length^2 for an area; all those other things that define a good square ;)

if you have black squares and orange squares and you are using a black table, you're more likely to pick the orange ones up first because they are easier to see, thus you have selected for the black squares and aided in the process of evolution. eventually, some of those black squares may begin to see other genetic mutations in their genes that may or may not be good. if, for instance, they had a change that began to make them not only black, but spiky and painful to grab, you would be even less likely to grab that type and you would have selected yet again. if the change was bad, say they began to turn brightly colored again, those squares would die and not make baby squares in the future.

Answer 2

First the selection pressure is represented by the prey having an UNFAVORABLE COLOR within an unsuitable environment. For example, if you have 10 yellow preys and 10 dark brown preys on a black background, the yellow organisms will be the more vulnerable of the two groups. They are more vulnerable (to be caught by a predator) because they stand out more, they are more visible on the black background. So, the predator will be more likely to catch the yellow ones, the "easy" ones. This does not mean that the predator is not going to catch any brown ones but it is less likely.

Second, since the yellow population is gradually reduced by the predator, the yellow prey, of course, is less likely to produce a large number of offspring compared to the brown prey who was not affected as much by the predator (remember the brown preys are better able to camouflage within their environment.) Basically, with time the yellow ones are weeded out, brown ones survive and leave more offspring behind. Brown is the color which eventually will become dominant. (N. B. The yellow and brown prey belong to the same species, so they can and will mate with one another. This will also affect the coloration of the surviving prey through the slow process of EVOLUTION. This is what happens--in a nutshell!!!) Hope this helps.

Answer 3

In a similar vein, which may help:
say you have 10 green, 10 brown, 10 yellow and 10 blue plastic counters (discs)...you throw them onto grass and then in 30 secs try to get as many as you can.
If you count them you would probably find that you would have more blue,yellow and brown and less of the green as they are more camoflauged in the grass.
In this case you are the predator and the plastic discs are the prey...the grass is their environment and how easy or hard they are too find is how easy or hard it is for preadtors to find their prey in an envrionment.

If you repeat the task a couple of time you woulod probably see similar results. Now if those discs could replicate, there are more green discs and they would produce more "offspring" as a result and over time the green would be the most common colour and the other colours may die out.

Now there is a severe drought.....you throw the discs onto the dry grass and do the same thing.....you would probably find that green and blue are the most easy to find and "eat" and that brown and yellow are harder....if you continued to repeat this, you would find less and less green and blue and more yellow and brown...if you assume that these all are able to reproduce.....

So summing up : if you started with the similar amounts of each colour, on a green surface, over time green would increase and the others would decrease......if there is a change in the environment eg drought you would find a disadvantage and would find that it would decrease and the yellow and brown would increase over time as it more suitable for that environment.....this is survival of the fittest and shows natural selection in that those best suited to the environment will survive and produce more offspring than those less well suited and over time those characters seen in the fittest will become dominant over other traits.

Answer 4

The previous answerers have pretty much answered your question. But here is a real life example of just such an adaptive change. It is the well known peppered moth example.