How does natural selection cause evolution to occur?

Answer 1

The presence of predators

Limited food-APEX

Answer 2

facts: 1)different individuals have different characteristics 2)these differences result in varying abilities to reproduce under local circumstances 3)some of these differences are inherited 4)those inherited differences that result in highly successful reproduction rates are the ones that will be present at higher percentages in the new generation. evoution is common sense.......and no humans did not 'come from apes' but they have very close common ancestors. Now, think about evolution on a family, tribe, society level. Some individuals preserve there species line by being protectors or servants. (ex: ants, bees, certain species of birds) further ex: if a son helps raise 20 of his siblings but does not reproduce himself, then, the DNA from his parents will still be transfered in great abundance even if he doesnt reproduce at all. sometimes behavioral evolution is harder to explain in only simple defintions. think about it.

Answer

Evolution is caused by environmental pressures killing off weaker members of the species and thereby "selecting" certain traits out of random genetic variations, ie natural selection.

"It's a fact that evolution exists, but there is a fight going on at present between scientific theories as to how humans came to be. We are thought to have come from apes, yet there is no proof of this"

This is completely untrue. There is no serious doubt among biologists that human and apes have a common ancestry, and even more importantly, that all life on earth has a common ancestry. The controversy is one invented by politicians and evangelists, it is not a legitimate scientific controversy.

The bit about knuckle-draggers is also a mistake, there were never "knuckle-draggers", that is a misrepresentation created when one fossil remain was found and was very hunched over as if it dragged it's knuckles when it walked, which inspired a cartoon from which the popular caveman conception originated. The truth of the matter is the individual was suffering from advanced scoliosis and other ailments, and had been badly crippled for many years, demonstrating that our primate ancestors cared for their sick and elderly.

Answer

Evolution is caused quite simply by environment. the need to change and adapt to one's surroundings. for example, a certain butterfly lived in forest with light brown trees. this butterfly was also light brown, it gave the butterfly the ability hide from predators. but this butterfly every once in a while would have black offspring. the black offspring would died though, because it could not hide from predators. Soon, during the industrial revolution, a coal factory was built right next to the forest. And soon, the forest trees were stained black because of the smoke. Now, the only butterfly offspring able to hide from predators were the black offspring. thus, the light brown butterfly evolved into a black butterfly

Answer

This is a most fundamental question and sits at the root of the Design (by God) versus evolution debate. In my view the mechanism of evolution is so subtle, and its products so sublime, that it (the mechanism) MUST have been designed by some sort of God.

Answer

To answer this question you have to define evolution first. The most basic definition is simply change. The cause of shifts in allele frequencies between generations can be separated into two distinct methods: sexual reproduction and asexual reproduction.

During sexual reproduction as long as two compatible organisms copulate their DNA will combine so that the offspring's DNA that differs from either parent but maintains similarities to both but cannot be identical to either. Thus you have evolution.

For species that produce asexually, DNA is copied from one generation to the next, so more often then not each daughter cell is essentially a clone of the parent. There are a large variety of environmental factors that can mutate DNA in the lifetime of a cell, but such cases are rare and often damages the cell too much for it to reproduce, so mutations in asexually reproducing organisms are more rare. Nonetheless, the frequency of reproduction is much higher resulting in higher populations and thus, higher chances of positive mutations due to environmental factors.

Evolution is change. That's all. That changes accumulate and form a phylogenetic tree is more attributed to natural selection. Natural selection is a result of evolution, but is not evolution itself. Understanding why we change can help you understand what evolution is and how it occurs. Understanding how we've evolved from single celled organisms requires an understanding of the mechanisms of evolution and natural selection combined.

Answer 3

By changing allele frequencies in populations of organisms. All organisms are variants, having traits that vary against the background of the immediate environment. A simplified explanation would be organisms that had varying alleles that conferred greater or lesser amounts of hair in an environment that was getting colder. Those that had a bit more insulating hair would survive better and reproduce more, thus leaving more decedents with the same traits which then would be variant and again the more hairy would reproduce against their conspecifics and the immediate environment. Thus the definition of evolution, the change of allele frequency over time in a population, would be fulfilled. This is how natural selection would work in this example.

Answer 4

Natural selection is variation in the number of offspring produced by organisms over time. The better the genome and adaptation to the particular environment are important factors. It can be random, too - like a volcanic eruption. Once an organism is past the age of reproduction natural selection is irrelevant.

Answer 5

Evolution happens because organisms reproduce with variation in inherited traits. Any and all change in the frequency of inherited traits in a population falls under the definition of evolution.

Natural selection is caused by the fact that populations exist in environments limited by the availability of Natural Resources and their ability to exploit these resources. Variant organisms from the same stock try and survive and reproduce the best they can. Variants that are better able to survive and procreate inevitably leave more offspring than their rivals. This causes the frequencies of their inherited traits to increase in the population. Note that I am excluding sexual selection from this description: a mechanism well worth a separate question.

Answer 6

Basically, genetic mutations are the result of the chaotic nature of nature at the smallest scales. The duplication of genes during reproduction is a chemical process, and like all chemical processes quite messy, due to the browsean motion of molecules at that scale. Much of this randomness is compensated for by additional molecular mechanisms that have evolved over time, but some of it is still propagated through the resulting offspring.

Answer 7

Natural selection does not cause evolution, it is simply a element in the process you might say. Those not adapted to the environment, the environment removes. It is a matter you might say of the ill adapted being weak of the flesh. Unable to stand the rigours of the environment, this is natural selection, when the environment does the selecting.

Answer 8

Basically natural selection causes speciation , which is the evolution of a new species. Take this example, there is a forest with one Species X , one day a river starts to form , splitting up this population into two. Due to climate change for example the weather on one side of the river may be hotter and dryer and on the other side the weather may be colder and wetter, these two species due to this geographical isolation can no longer interbreed. Due to these two different conditions/environments , there will be different selection pressures. This selection pressure will change the allele frequency within the population and favour the advantageous alleles ; for example those organisms with shorter fur in the hotter conditions will have an increased likelihood of passing on their gens to the next generation , compared to an organisms with longer fur. Due to these changes in allele frequency the two populations will eventually become two different species, even when the physical barrier disappears , in this case the river , the two species will have reproductive isolation , such as sterility where if breeding is successful the offspring will be infertile . I hope this helps you , ORCA-93

:)

Answer 9

Over time the action of natural selection causes a change in the makeup of the population: it becomes composed more and more of individuals who possess those successful traits. This change in the genetic makeup of a population is called evolution.

Answer 10

Evolution is the gradual change of any species (plant, animal, insect, human, etc) over generations to become better adapted to, or in response to natural selection by, its habitat. It is not a question of gaining something it needs, it is a question of becoming better at propagating a sustainable population that will continue to provide for itself at a steady rate for future generations to propagate at a healthy, sustainable rate as well, or the changing environmental conditions naturally selecting certain traits out of the population.

Once a species "has" what it "needs" evolution does not stop. Instead, the species continues to evolve to its environmental conditions, whether that means specializing in a task by growing stronger teeth, more flexible stalks etc, or becoming more of a generalist that can apply its abilities to a broad scope of tasks like racoons, houseflies etc.

Sometimes evolution destroys species populations as their environments change, as is the case with small, Flightless Birds like the kiwi, which evolved to have stunted, useless wings, since it was a waste of their calories to grow full-strength wings, and put that calorie intake to growing bigger feet, stronger sense of smell, tougher skin etc. When a ground cover predator was introduced to New Zealand (common house cats) the kiwi could not fly away, and the cats had a field day on the small, plump birds.

unfortunately for the kiwi, the natural selection that would, over time, cause stronger, healthier wings to show up in the population, is going too fast for their population to adjust, so they are likely to go extinct. such is the nature of natural selection, as sad as it is, which is why it is so important for us as human beings to be careful not to introduce exotic species (species not native to any given area) into an environment, and to work to conserve things that we have put at risk (most endangered species are our fault....). But all in all....that is a small sliver of evolution.