Natural Selection

Survival of the fittest is a not quite accurate phrase for natural selection. Natural selection is,

The non-random survival and reproductive success of randomly varying organisms.

Natural selection creates a stronger species that is able to live longer and produce more. It continues to work because after a few generations, the traits will become common in the population.

Comparative DNA samples from chimpanzees and humans show very well the concept of evolutionary common ancestry. Aside from that, the differences in DNA among organisms, especially at certain loci, show how long two, or more, organisms shared common ancestry.

Variant traits that increase the number of offspring become common in a population, causing the overal morphology and behaviour of the population to continuously shift to give the best reproductive chances for any given environment.

As spices develop they create variations. That means differences creep in. Those differences are called variations. Every now and then one of those differences makes it so that a particular individual or group of individuals can better adapt to a particular place.

The similarity between natural selection and selective breeding is that they both produce changes in plants and animals.

Abiogenesis, or more commonly known as the origin of life itself, is not part of Darwin's theory of evolution.

The phenotype of organisms determines the way they interact with one another and with their environment. The way organisms interact with one another and with their environment determines how well each organism is able to compete for resources and mates - what the chances are of that organism successfully raising fertile offspring, in other words. Such offspring will likely carry the genes that give them their parent's successful phenotype. So over the generations, the genes that produce such successful phenotypes will become more numerous in the population, causing a shift in the average of phenotypes towards this successful phenotype.

The 3 types of selection pressure on a population:

1) "Stabilizing selection" = intermediate phenotypes are favored and extremes on both ends are eliminated.

2)"Directional selection" = is a mode of natural selection in which a single phenotype is favored, causing the allele frequency to continuously shift in one direction.

3) "Disruptive selection/ Diversifying selection" = describes changes in population genetics in which extreme values for a trait are favored over intermediate values

A nominated COR frequently is asked to write evaluation factors during the source selection process.

Natural selection doesn't reduce variation. Variation is regulated by the rate of mutation.

Natural selection reduces the chance of bad variation from being passed on and increases the chances for good variation to be passed on.

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Natural Selection is driven by random mutations and sexual reproduction. Organisms produce more offspring than can survive. These offspring compete for resources for food and water and who can aviod stuff such as predators and disease. Sexual Reproduction allows a population to have variation. If all of a population was the same, then it could easily die out if it had a adaptation that decreased its chance of survival. With sexual reproduction, all of a population has some sort of variation. Random Mutations allow organisms to gain new adaptions to help them survive in their environment. Together, Random mutations and sexual reproduction allow organisms that can survive in their environment survive and pass on their genes to their offspring.

Fitness is a measure of the ability to survive and produce more offspring relative to other members of the population a given environment. Natural Selection is is a mechanism by which individuals that have inherited beneficial adaptations produce more offspring on average than do other individuals.

So how does these two things relate? But the offspring must survive to contribute to the following generation, so fitness as a generational value. An individual's fitness became defined as to how well that individual contributed its genes to the next generation. The bottom line is still how many successful offspring an individual has.

The basis for all science, be it evolution or the study of how squeaky noises annoy people, is evidence. Darwin's primary evidence for evolution by natural selection was morphological homology; physical similarities between species. Modern evidence for evolution by natural selection is vast and includes a rich fossil record, well understood geologic evidence, radioisotopic evidence, as well as a host of genetic evidence from protein homologies to complex molecular systematics. All evidence for evolution converges on the singular observation that all organisms can be organized in a nested hierarchy much like a family tree; a Tree of Life.

Natural selection works on a simple premise that the better equipped have more chance of survival and reproduction. The fact that the 'better' animal has more chance of producing offspring means more of his or her genes reach the next generation than his or her weaker rivals, thus weakness is filtered out. Although luck and chance can come into the equation (a 'weaker' animal may get lucky) in the long run over generations and generations, luck is no match for 'good' genes which enable advantages in the fight for survival. The chemical process of reproduction is slightly different. When cells are creating copies of themselves to make the new being, they are essentially copying enormous sets of instructions that their parents cells followed to create them, and the offsprings cells will use to build them. As the instructions are so huge, the number of cells involved is so colossal, the number of animals involved in reproducing is vast, and the number of generations and generations, and millions and millions of years… the opportunity for 'mistakes' is likewise gigantic, no matter how accurate and efficient the cells involved are supposed to be. These 'chance' mistakes are actually something like 1 in a giga-mega-godzillion (not an official statistical measure I might add!) but because the process happens more than a giga-mega-godzillion times, mutations are seen to occur. These mutations can either improve the animal slightly, or hinder it. The mutations are never that huge as the new being would be unable to survive or find a mate if it drastically differed from the species as a whole. Of course, any improved instructions which give the being a slight advantage, have more chances of being copied in the future - the mutation is now the new standard. An interesting position on this is that cells actually evolved with this chance of mutation. Cells which were 100% accurate in their reproductive instruction copying never hit upon anything new, or advantageous to the species while the world changed around them. What was a good design then, perhaps isn't so good in today's world. Meanwhile, cells which had a 99.999999…..% accuracy were actually more successful in the fight for survival as they enabled the opportunity for mutation, and thus the opportunity for improvement - a species which can change with time is far more likely to survive in a world that too changes with time. With this in mind, you could argue randomness in cell mutation was actually naturally selected by a non-random process!

Because one cannot understand evolution without it. It is the primary driving mechanism of evolution; the mechanism that gives evolution its direction. If one is to learn about biology at all, one must have at least a basic understanding of the mechanism that produced all of today's biological variety.

Natural Selection is the process of organisms adapting and evolving with their surroundings. The weaker ones who cannot adapt die off while the adapting ones stay alive.

"The excess fecundity, and consequent competition to survive, in every species provides the precondition for the process Darwin called natural selection. Natural selection is easiest to understand as a logical argument, leading from premises to conclusion. The argument requires the four conditions listed below.

1. Reproduction. Entities must reproduce to form a new generation.

2. Heredity. The offspring must tend to resemble their parents: roughly speaking, 'like must produce like'. This condition is provided by Mendelian inheritance.

3. Variation in characteristics of the members of the population.

4. Variation in the fitness of organisms associated with these characteristics.

Provided these conditions are met for any property of a species, natural selection automatically results, as in the case of the peppered moth. If any are not, it does not. Thus entities, like planets, that do not reproduce cannot evolve by natural selection. But when the four conditions apply, the organisms with the property conferring higher fitness will leave more offspring, and the frequency of that type of organism will increase in the population."

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Which does not add new alleles to a population gene pool?

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