Natural Selection

Dolphins, like all other life, are entirely formed by natural selection. There's not a single part of them that hasn't been touched, over the course of their evolutionary history, reaching back to the first cellular lifeforms, by natural selection: from their overall shape and colour to the metabolic pathways in their cells.

One of the most apparent adaptations of dolphins, relative to other (land-dwelling) mammals, but not unique to dolphins alone, is the adaptation of their morphology and physiology to a completely aquatic existence.

Natural selection is the nonrandom survival and reproductive success of randomly varying individual organisms.

All populations of organisms vary, more are reproduced than can survive on the resources the immediate environment provides, some have the variant traits needed to survive and reproduce more successfully than conspecifics against the immediate environment and these individuals are said to be naturally selected.

Polygenic traits occur because of genes and environment. There are usually two or more genes involved in these traits. It also takes into consideration where the organism lives, for example the fact that some hotter areas have a history of people with darker skin tones.

Darwinism is often what opponents to evolution call evolution to make it sound like some sort of Darwin cult, but it can also be used to just refer to evolution through natural selection as it was understood in the late 1800s, though that is usually called darwinian evolution rather than "darwinism".

Also social darwinism is the application of natural selection to human civilization, the idea that the poor should starve to death because they're "weaker" etc. A faulty injection of biological science into social philosophy.

Mutations allow natural selection to occur. The mutation in a species that causes it to be the most fit will survive. the others die off. So, naturally, it is called survival of the fittest, the weak die off and the fit live on, passing their good traits to offspring. This is nature's way of perfecting a species. Mutations introduce new genetic information to an organism's genetic code

Natural variation in artificial selection is used because humans choose from among the naturally occurring variation s in species. Natural selection is related to species fitness because Darwin called natural selection survival of the fittest because those that could survive would carry their species on there for being the naturally selected.

All organisms need food, water, and shelter in order to live, grow, and reproduce.

Both establish that:

1. There are limited reproductive opportunities

2. Only those organisms with "favorable" traits will be allowed to reproduce and pass the traits onto their offspring

The difference is that artificial selection involves human intervention

small changes add up over time

His law is to make DNA more efficent.

His law of natural selection states that organisms more suited to their environment will have a higher success rate, and are more likely to reproduce. Therefore their genetics are more likely to continue into the future.

It means the reproductively fittest organisms have offspring that carry the traits that made them reproductively fit. Remember, the fittest survive to reproduce, not the strongest. In some immediate environments, among humans, that could mean the richest, the funniest, the famous, or even the luckiest.

Because many people found it contary to The Bible's - and the Church's - teachings that man had been created by God. Also many people thought the concept repugnant and or impossible that man had 'descended from the apes'.

Variations within a population. Variations mean traits that only certain individuals have that give the individual a greater or lesser chance of reproducing.

Nature selects against only harmful traits

Without variation natural selection could not select among members of a population that were all the same. How would these organisms become reproductively successful if they did not vary in the traits that allowed some to survive and reproduce, while others don't while changing the allele frequency of the population, which is the definition of evolution?

survival - those that live have the babies and their genetic profile is perpetuated. Those that die don't have offspring and therefore their genetic profile become extinct.

Well, there is a major difference between natural selection and "unnatural selection", as I call it. What you are talking about with selective breeding is what I call unnatural selection: An artificially imposed criteria for success. If you're trying to get a dog with blue stripes, a dog with blue stripes will be more likely to survive even though genetically it's most likely a dead end.

But I digress.

Natural selection/evolution works as follows: First you have the mutation, then the selection. Over the course of generations, you occasionally have mutations. These can be of a few types: fatal, semi-fatal, neutral or beneficial. Now, if the mutation is fatal or semi-fatal, then the creature in question will almost definitely not be able to reproduce and pass down this genetic flaw (except in humans, with our advanced medicine) so this mutation effectively destroys its own chance of making it into the gene pool. A neutral mutation would not make it any more or less likely for the creature to live or die, to breed or not breed, so it would effectively have no effect.

A beneficial mutation however, would improve its chances. So now you have a creature with a beneficial mutation. This could make its reaction time very slightly faster, or it breeds more quickly, or it has slightly better camoflage (keep in mind, mutations are ITERATIVE. This means they make very tiny adjustments to the creature, not big leaps). Now, if that creature does something better, theres a higher chance of it surviving and breeding. If it survives and breeds, its children inherit this advantage. If its children are successful too, then on it goes.

If repeated mutations make the resulting successful creature different enough, eventually you get a new creature, which goes down its own evolutionary path, separate from the creature it originally was generations ago.

And there you have it, evolution in a nutshell.

Everything from available food to climate will cause the changes we see in natural selection. Random mutations occur constantly and when those mutations are beneficial for life, the genetic code is more likely to be passed on to future generations.

A process in nature in which organisms possessing certain genotypic characteristics that make them better adjusted to an environment tend to survive, reproduce, increase in number or frequency, and therefore, are able to transmit and perpetuate their essential genotypic qualities to succeeding generations.

Natural Selection

Natural Selection

Natural selection is the differential survival and reproduction of individuals due to differences in phenotype. It is a key mechanism of evolution, the change in the heritable traits characteristic of a population over generations. Charles Darwin popularised the term "natural selection", contrasting it with artificial selection, which in his view is intentional, whereas natural selection is not.

genetic drift is a change in evolution based on small mutations in genetic make up over generations

natural selection is survival of the fittest, where only the surviving species will reproduce and live on

natural selection is caused partly due to genetic drift, since the mutated species will adapt to their surroundings and therefore become the fittest species.

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 result is adaptation and evolution, as improved traits should increase the population of the best species over time.

Each individual in a population behaves in a slightly different manner.