What is natural selection, and how does it explain the evolution of life on Earth?

Answer 1

Natural selection operates thusly:

1. Individual members of a species vary. Just looking at the people around you will show this to you. Although it is harder to see that for people who are not naturalists, it is the case in all living species.

2. Some differences among individuals allow some individuals to leave more descendants than other individuals. This may be because the differences allow those individuals to live longer, or it may be that the differences allow those individuals to out reproduce others. This is what is meant by evolutionary "fitness". Note that the term "survival of the fittest" is imprecise: survival is not the deciding factor, reproductive success is; also "fittest" implies a single individual "wins", rather, overall all the member with that successful difference should "win", barring adverse chance (AKA, bad luck).

3. Over time, the species will have higher and higher numbers of individuals with the advantageous traits. Over a long period of time the species will change. Some times this means the species as a whole will be a different species than their ancestors a few thousand generations were, more often this means that different populations of a species have changed so much over time that they can no longer interbreed and are thus different species.

This is analogus to what humans do with domesticated plants and animals, but over a longer period of time.

Natural selction is not the only evolutionary force acting on species, but most workers agree that it is the most consistent and usually the most important evolutionary force.

Natural selection operates towards a goal; the goal of producing individuals that are as well adapted for their environments as it is possible, given their genetics and the variability present in their genomes.

Answer 2

Ok im a university student studying this exact topic right now.
Natural selection first stated by Darwin says that : Organisms that survive in the next generation survive longer to reproduce. This means that natural selection acta on your genes that favour your survival. For example if there are two different types of birds but of the two one has a slightly smaller beak size and is limited to eating only small seeds, whereas the other bird has a slightly larger beak and can eat both the small and large seeds. Now lets say these two birds are in a certain area where suddenly there is a decrease in the SMALL seeds. The birds with smaller beaks will have no food therefore natural selection will act towards the bird with the larger beak. And hence the smaller birds will mostlikely be reduced in population and larger birds will increase. So now that natural selection has acted on birds with larger beaks, then one can say that the birds with larger beaks will survive longer than the birds with smaller beaks and therefore have more offsprings. The birds have now EVOLVED into larger beaked birds since all the small beaked ones had less of an advantage. As you can see small changed like this have and effect on the preceeding generations and little by little generation after generation natural selection changes some feature of the offspring and this is how they evolve!

Answer 3

Natural selection is the culling of a species that cannot survive or reproduce. Natural selection reads into the survival of the organism, if it reproduces and variations that derive from the survivors and the extinctions of like variations that don't supply the gene pool.

Life earth are evolved selections.

Answer 4

it says that nature indirectly chooses the stronger species. by having certain traits, traits that will allow you to adapt to the enviroment, you are able to live longer. adaptation is the key.