What role does DNA play in mutation natural selection and sexual selection?

Answer 1

DNA is fundamental to our understanding of evolution. DNA does not change and so showing evolution over time, but it is merely evidence of an evolutionary link between certain species. For example, DNA is extremely similar between humans and apes. Darwin and his theory suggested that modern humans developed from apes through evolution. The fact that human and ape DNA is about 97.5% the same shows a possible link between our possible ancestors and humans.

Because DNA provides much of the information about ourselves. DNA also can give clues about a person's intelligence. Intelligence seems to be more important than brute strength from an evolutionary standpoint, because we humans used our phenomenal smarts to outwit other stronger species to get food.

Mutation is an interesting topic because it can be for the better or for the worse. Mutations are caused by an error or misprint in the DNA as the DNA is being 'printed out' by enzymes. In other words, a mutation is simply a mistake in our DNA. Humans have about an average of 50 mutations in our DNA, and generally few or none are harmful.

A possible mutation that we humans have is dairy tolerance from cows and sheep, goats, even CAMELS after we reach the age of three.

The trait for blue eyes is actually a mutation that stems from one person almost 10,000 years ago and it and the lack of skin pigment that goes with it allowed us to live in areas with low sunlight.

Each organism gets chromosomes from both their mother and father, and the number obviously varies between species. Humans, for instance, have 46 chromosomes, which consist of one set of 23 from each parent. These 23 pairs of chromosomes are contained within the nucleus of our cells.

DNA replicates itself by unraveling the double helix and making copies of the original strands through the aid of enzymes.

Chromosomes are prone to 4 kinds of mutations: deletion, duplication, inversion, and translocation. Deletion happens when a section is not replicated. Inversion happens when a section flips itself inward (i.e. head over heels) from its original position. Duplication happens when a section is doubled. Translocation happens when the section of one chromosome is switched with a section from another chromosome. This happens because chromosomes fold over each other during replication. This can sometimes result in the complete fusion of separate chromosomes (this is why humans have 46 and our relatives the chimps have 48).

Humans and other organisms commonly have thousands of non-harmful mutations in their genes and chromosomes. However, these mutations can sometimes have negative or beneficial effects. A negative example would be the way base pair substitution in the hemoglobin gene can lead to Sickle-Cell Anemia. This nasty disease causes red blood cells to take on a sickle shape, which can lead to complications like stroke and kidney failure. The disease plagues many African-Americans. Oddly enough, SCE is also a beneficial example. The gene mutation that causes SCE is believed to have arisen in Africa where it provides people with a resistance to malaria.

The primary function of all life is to pass on genes to the next generation. Those who have more children are considered to be the fittest in their environment. If a random mutation provides an organism with a survival advantage, they will be able to pass on more genes than their peers.

A survival advantage could be a fish being born with a bony segment in its fins that would allow it to travel briefly between shrinking water sources during a time of drought or to catch prey on the shoreline during aquatic food shortages.

The fish would naturally survive longer than those born without this mutation and pass on more genes. This means the environment would determine the mutation to be beneficial. This is known as Natural Selection.

Natural Selection is the mechanism that drives evolution. This is because random mutations can accumulate over periods of deep time to produce large scale changes in the morphology of a species until they become a new species altogether.

The fish I described above is actually an ancient species known as the Lobed-Fin, which first waddled the earth some 400 million years ago. Natural selection eventually caused the descendants of this fish to take on more adaptations better suited for life on land, including lungs (adapted air bladders) and jointed limbs. Groups split off during the following ages to give rise to the amphibians, reptiles, birds, and mammals (including humans). All of this diversity came from only small incremental changes over millions of years.

Sexual Selection is a type of Natural Selection. But instead of the environment determining whether a trait is beneficial, it is the female of a species that determines the benefit.

Females tend to choose mating partners based on physical attributes that signal the resulting offspring will survive to pass on their genes.

Female Gorillas, for example, are half the size of males because they select powerful mating partners. Males battle each other for mating rights with the females. Males who are the biggest and the strongest stand a better chance of passing on their genes and producing offspring with the same traits.

This explains why gorillas are so much larger than the other great apes. Another example is the tail of a male Peacock. Females select males with larger, more ornate tails to mate with.

The tails are actually quite heavy and create a risk to the male because it costs extra energy to maintain such a secondary sexual characteristic not to mention the fact that the extra weight would slow escape from a predator. But the size and color of the tail signals to the female that the male is strong with good genes. These characteristics were initially conceived through mutation and then built upon through sexual selection.