3. What are Hox genes and why are they thought to be important to understanding the evolution of complex adaptions? How are Hox genes related to cascading networks and what happens to those networks if the required Hox genes donât work properly, and why would this be the case? Describe a specific example that demonstrates how an understanding of Hox genes is able to help us understand how a complex adaptation evolved.

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OC4149121Lv10

8 Jan 2022

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Elin HesselLv2

9 May 2018

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The Human Genome Project (HGP) has provided us with a map of our entire genetic code. Studying the human genome may help us discover the answers to many questions including: how many genes we have, how specific genes work, how living things have evolved, how single cells can develop into complex organisms, and how what's in our DNA can cause us to become ill. Most people would say that this information could provide information that would lead to developments in medicine and new ways to prevent, diagnose, and treat diseases. Some people, however, have also acknowledged the dangers of this kind of information, for example genetic profiling might lead to discrimination. Some examples might be that if it is determined by genetic testing that a person has a high risk of developing cancer, should employers be allowed to refuse employment on these grounds? Should insurance companies be allowed to deny them health insurance? What are some of the ethical or other questions that you think can result because of the HGP? As an individual, how might you live your life differently if you know about your genetic predispositions?

crimsondeer38

For years we have been able to analyze the fossils of extincthumans like those of Neanderthals. Their bones gave us clues to howthey looked, how they lived, and how they might be related to us.In the last few years, we have been able to get a better view intothese extinct species and their relationship to our species. Thanksto next generation genomic sequencing technologies, we have beenable to obtain genetic data on Neanderthals, Denisovans and othersthat have allowed us to make direct comparisons between our speciesand theirs. In addition, we have been able to observe the presenceof DNA from these extinct species within our own genomes which tellus that we had kids with these now extinct humans.

If we take Neanderthal DNA as an example, we find that we share99.5 percent of our DNA with them. Which means that we andNeanderthals were separated from each other for more than 500,000years. This also means that we were genetically similar enough tobe able to have offspring with each other. We see evidence of thisgenetic introgression between us and Neanderthals when we look atour DNA. Interestingly, if we obtain one thousand DNA samples fromGrossmont College students, we estimate that we would be able toextract at least 20% of the Neanderthal genome from them. Thismeans that 20% of our collective nucleotide sequences are sharedwith Neanderthals but this doesnât mean that 20% of our genes areNeanderthal specific genes. Of the twenty-one thousand genes thatNeanderthals had, only a few dozen of their genes survive withinour genome. The same holds true for Denisovans. What is moreinteresting is that older versions of ourselves have a tendency tohave higher levels of DNA from extinct humans compared toourselves. In other words, over the course of thousands of years wehave been slowly weeding out the DNA of the other humans from ourgenome in favor of our genes.

One basic question that we might like to ask is why have we beenlosing Neanderthal and Denisovan genes over time? Also, why do westill have a significant amount of DNA segments that donât seem tobe going anywhere? The answer to this has to do with selection.

The answer to the first part of the question has to do with thefact that we were not fully genetically compatible with the otherhuman species to begin with. Basically, to have had Neanderthal orDenisovan genes in the past meant that an individual's level offitness was reduced. To get rid of their genes in favor of our ownwould mean that the relative fitness of individuals would increaseovertime.

The answer to the second question has to do with the fact thatDNA segments from Neanderthals and Denisovans that did not code forproteins remained because there was little selective pressureagainst them. As far as genes are concerned, the only Neanderthaland Denisovan genes that remain only exist because they had aselective advantage or at least have been neutral to ourspecies.

DNA segments that that were neutral or that had a selectiveadvantage, whether genes or not, simply remained because they wereadvantages or there was little selective pressure against them.

Your task for this week is to look for information about oneNeanderthal or Denisovan gene that survive within our species andto tell me what function that gene has and how that gene mayincrease the fitness of modern human populations.

In your post, discussONE Neanderthal orDenisovan gene that is currently found within our species.
- Tell us about the gene and its function. Explain what it doesfor us. (Make sure you give a citation.)
- Explain in your own words any possible advantages that yourNeanderthal or Denisovan gene might have. Make sure you give ininformed opinion that is grounded in your research.

azurecrow764

1/ What is the difference between the different patterns ofselection: directional, stabilizing, anddiversifying?

2/ How do bacteria acquire genetic variation and how does thatdiffer from the mechanism by which humans acquire variation?

3/ What were the key observations made by Darwin to develop thebasic tenants of the theory of evolution? Has thistheory been tested?

4/ What are the most common misconceptionsabout evolution and why are they not valid arguments againstevolution?

5/ The key component of the theory of evolution isnatural selection. Define this process. Why is itcommonly known as âsurvival of the fittestâ? What are examples offactors (selective pressures) that drive evolutionof populations?

6/ What is the indirect evidence of evolution? What arehomologous and analogousstructures? What is convergent evolution?How does similarity of proteins between different species supportthe idea of evolution?

7/ Be able to explain why the following statement is true:Natural Selection works on individuals while evolution works onpopulations over generations. Or to put it another way: Individualsdo not evolve, populations do.

8/ How can evolution explain theformation of complex structures such as the eye or the flagellamotor?

9/ What causes variation in a species? To putthis another way: all humans have the same genes, yet we do notlook alike. What is the reason for the phenotypicdifferences between individuals of the same species? What isgenetic recombination?

10/ What are the dangers of small populations of a species froma genetic and evolutionary standpoint? What is thebottleneck effect?

11. How does speciation occur? What is theimportance of geographic isolation? How is thisillustrated in the Galapagos?

12. What is Darwinian Medicine and how does ithelp us better understand medical conditions?