DNA Day experts answer your questions about DNA and evolution

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Does DNA relate to evolution in any way?

Yes DNA does relate to evolution, in fact that is what evolution works on - it selects for mutations that give an organism a selective advantage in nature.

- Answer provided by Dr. Dennis McCormac

Does genetics and evolution influence each other?

In fact, that is true. Evolution is in fact the result of a process called Natural Selection, in which certain heritable (genetic) traits of an organism may provide that organism with a greater chance for survival and reproductive success (often times called Fitness). So if a genetic trait allows an organism to survive and reproduce more often, they are more likely to pass on that trait to their offspring, who will then carry that trait and pass it on their offspring as well (in a repeated cycle). So over time/generations, the population may evolve to have more of that original trait which offered a reproductive advantage. This explanation may be a little confusing, so I'll give you an example: Imagine there is an initial population of blue and green caterpillars, but the green ones get eaten by birds less often because they are better able to camouflage to the leaves that that are sitting on and eating. So over generations more green caterpillars will survive and reproduce, so that over time there may be very few (if any) blue caterpillars left in that population. In this case, the genetic trait of body color has caused the population to evolve!

- Answer provided by Harman Sawhney

How does DNA change when an organism changes dramatically through evolution? (ie. four-legged mammal to a whale)

The changes in DNA through evolution are actually quite small in terms of the total genome. Mammals share a very high similarity in their total genome (generally over 90% is the same), so it is actually tiny little changes that result in what seems to us as humans as a big change...it is amazing to think that just a couple small changes in DNA can result in the huge changes in phenotype! Evolutionary changes are the same as any mutational change... it results in a change of an A, C, T or G!

- Answer provided by Dr. Monique Haakensen

According to the theory of evolution, all life shares a common ancestor. Bearing that in mind, how far back would it be possible to trace similarities in species' DNA, if that's even possible?

Tracing back ancestry is limited by the intactness of the DNA found in fossils. The further back you go the more difficult it is to obtain intact DNA that can be sequenced.

- Answer provided by Dr. Gijs Van Rooijen

Will our DNA/ genetic structure change in the future to adapt? How so and by how much?

This is a big question but let me explain two things. Our DNA changes over the course of our lives not only because of spontaneous mutation, but also because of DNA Replication errors etc. Most of this is corrected because of proof reading and sometimes these errors have no manifestation of negative consequences. BUt sometime they do (ie. cancer) so this can be a problem. DNA also change due to environment in an epigenetic way. These can be good or bad. These usually happen in a relatively short time frame. In a longer time frame like evolution, mutations that occur randomly can be selected for over time if they give the organism an advantage in the environment.

- Answer provided by Dr. Dennis McCormac

How much change does the DNA needs until it is a different species?

This is a challenging question because it depends upon both the region of the genome and the species involved. There can be lots of differences in non-coding DNA within the same species and we use this variation for DNA fingerprinting. Within the 'barcode' region of the mitochondrial COI gene used to tell animal species apart, most specimens within species have sequences with 98% similarity. However, speciation is a process and young species might not have accumulated many mutations, hence share barcodes.

- Answer provided by Dr. Robert Hanner

Do you think humans have evolved from mutations in our DNA?

Well yes of course ... if our genomes were the same as those of Homo erectus a million years ago, we'd be Homo erectus still. And likely not doing what we're doing right now! But don't forget there's more to genomics than simply mutations. That's one of the most intriguing things being discovered - that you and I can have exactly the same genes and yet be different. Of course mutations are an important part of the evolution of any species, although it's not just mutations. For instance, mutations are not 'good' or 'bad' in and of themselves. The real question is, do they enhance the animal's survival and reproduction, or not.

- Answer provided by Jay Ingram

When along the line in evolution did self-reproduction end? Why would it end? Wouldn't it be more advantageous for creatures to self-reproduce?

That's actually a complicated question with lots of arguments haveing been put forward as to why sex, inside of just splitting in half, is better. One apparent advantage is that by mixing genes between two individuals you introduce much-needed genetic variation. That helps in providing opportunities for evolution.

- Answer provided by Jay Ingram

Do you think that our genes bottleneck our potential as humans?

Hmm, maybe? I'm not sure what you mean by bottleneck here. In population genetics, bottleneck is a reduction in genetic diversity because of small population size. This we have seen in humans. We're fairly confident that drastic reductions in human population numbers have led to genetic bottlenecks during our evolution. But - if you are asking if genes simply limit our potential, the answer could also be "yes". We are a function of our genes. Genetics is generally a trade off. An allele that makes us adapted to something, but make us less adapted to something else. This trade off is probably one of the reasons for the obesity epidemic we are facing in Western society. Our genetic make up makes us very good at storing calories as fat. This was an adaptation when food was scarce and we had to hang on to every calorie that we could get. Now that chips and soda are everywhere - and we less active than we ever have been - our bodies are still packing on fat as if we have no idea when we'll eat again.

- Answer provided by Dr. Thomas Merritt

Will our genetic coding change over time?

Yes, to a certain extent. We pick up mutations in our code over time and acquire "new" DNA from our ancestors. However, too many changes will be lethal and therefore not passed on

- Answer provided by Dr. Gijs Van Rooijen

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