So we got a bit of a late start this year. I decided to extend my vacation by a few days, and did not get home in time to unpack and still have time to get something up here. So this is the first post that will count towards your grade. From now on, unless something comes up, posts will go up on Monday nights or Tuesday during the day.
Why is there sex?
Some interesting new research on the reason sexual reproduction is so prevalent. Asexual reproduction has many benefits; so many in fact, that many researchers state that genes coding for sexual selection should have been been competed out by asexually reproducing organisms.
The reason that sexual reproduction persists is due to parasites. Asexual organisms cannot respond to parasites by recombining their genes the way sexual organisms can. New research seems to support this hypothesis, using a roundworm host and a bacterial parasite.
51 comments:
I found this article very interesting. I have never really thought about why evolution favors sexual reproduction and this article has proof as to why it does so. And now that I have read this article, it seems obvious that an advantage, such as the ability to create a less vulnerable strain of a species, makes the effort to have sex more reasonable. Sex would not have evolved, and been retained, unless it had some advantage of this scale. It would be stupid for a process as elaborate, ubiquitous, and expensive as sexual reproduction to be maintained without serving this important purpose.
The Red Queen Hypothesis that the author refers to also appealed to me. It suggests that animals have sex in order to constantly improve, each strain getting better than the last. Yet doing so provides no automatic guarantee of winning the struggle known as “survival of the fittest.” This is evident from the experimental support that the author uses. With asexual reproduction, the hosts will die out very quickly (20 generations). But with sexual reproduction, the hosts had much lower mortality rates – very cool.
Lovely article to start the summer assignment off with, Dr. H.
I find it amazingly convenient that species of animals, plants, even bacteria and micro-organisms can cycle through many generations in a short amount of time, making them perfect specimens to test theories of evolution that could be relevant to humans. Performing such an experiment on a more complex animal then a worm, like a cat or dog, would take so many more years because their lifespan is so much greater. In humans, this sort of testing would be impossible. Fortunately, we are able to use species like worms, flies, etc. to look for evolution when the same experiment could take hundreds of years if it were done with 30 generations of humans.
So, what I got from this article was that the reason that sexual reproduction persists over asexual is because of the fact that sexually reproductive organisms are able to better at adapting to hazards in their environment, such as parasites. This has to do with the way sexually reproductive organisms recombine their genes into unique combinations during each generation, leading to new genetic advantages which are reproduced throughout their species due to natural selection. Asexual organisms, however, do not experience such evolution and suffer greater from parasites, especially if the parasite evolves itself. In studies, where this hypothesis (known as the Red Queen Theory) was tested, it was shown that asexual organisms can even have their population decimated as a result of evolving parasites, whereas sexually reproductive organisms evolve in response to their parasites leading to a more stable population. In contrast, if the parasite does not evolve, organisms that could reproduce, sexually, asexually or both favored sexual reproduction. It seems that the reason that sexual reproduction persists is because of it's ability to cause evolution and help organisms survive environmental hazards like parasites.
Hypothetically speaking, asexual organisms should be able to outrun sexual organisms in the evolutionary race. Obviously, this is currently not the case because sexual reproduction clearly remains prevalent. Around the 1970s, scientist developed the Red Queen Hypothesis which states that natural selection favors parasites that infect the more common strain of host. However, other more dominant, resistant strains naturally develop and begin to thrive among a species. In terms of survival, asexual organisms have a higher mortality rate because they cannot withstand an evolving parasite. Therefore, when asexual organisms begin to multiply or “boom” they are significantly subdued. Sexual organisms, on the other hand, can ward off potentially dangerous parasites because they have the ability to alter their genetic makeup making it harder for a parasite to adapt. Recent studies involving a species of worm known as Caenorhabditis elegans and a parasite deemed Serratia marcescens proves this hypothesis valid.
In other words in order to fulfill survival of the fittest, genes need to be recombined to reduce the threat of new strains of bacteria. Asexual reproduction might seem more efficient but it lacks the ability to recombine different genes when compared to sexual reproduction. Without this combination of genes from two organisms, posterior generations would not be capable of fighting off parasites leading to a decline in many plant and animal species. So in order for evolution to work properly, organisms still need sexual reproduction as a way of ensuring their species will remain in existence.
I found this article very interesting. I've never really thought about the function of sex, besides creating life, until now!
If you think about it, asexual production should be more prevalent than sexual reproduction when you look at its pros. Asexual reproduction requires no effort to find a mate, and efficiently produces carbon-copied offspring of the parent organism. But when you bring parasites into the picture, it makes sense that sexual reproduction is the better way to go. Just one bad parasite strain can knock out an entire line of asexual organisms because of the fact that they all have the same gene code. Sexual reproduction, though, gives an early defense against these strains by creating multiple types of gene codes in a generation. This provides a greater chance of a species surviving if it is attacked by a certain disease or parasite strain.
I think the part that most interested me in this article was that in the second experiment with the roundworms, the worms that coevolved with the bacteria became the most sexual. On further observation, this completely supports the Red Queen hypothesis. In order to survive, both the worm and bacteria had to continuously develop in order to keep their numbers strong. The worm, therefore, was forced to become more sexually reproductive to protect against the bacteria. In turn, both parasite and host both helped each other to evolve. Sexual reproduction not only keep our planet populated, but allows for organisms to help each other grow and develop.
I never sat down and wondered why there is sex but I am truly surprised that it is due to parasites! I always assumed sex was just a way that animals reproduced and kept their species alive, not for survival. But, after reading the article, I am now aware that evolution has favored sexual reproduction rather than asexual reproduction because sex allows organisms to fight against parasites. I found it amazing that in the experiment conducted at Indiana University, asexual worms co-evolving with the germs died, while asexual worms were fine when the germs could not evolve. Furthermore, the sexual worms suffered lower death rates altogether! The other experiment demonstrates the relationship between bacteria and the amount of sex the worms had and was also very surprising.
The results of the worm and bacteria experiment carried out by scientists from Indiana University provided substantial evidence for the validity of the "Red Queen" model. I had a better understanding of the concept after reading the results of the experiment. To me, it seems credible that sexual organisms can have a higher mortality rate than asexual organisms. After all, sex diversifies the genes, which gives parasites a harder time trying to acclimate to the new gene code.
What puzzled me in article was one result of the second experiment. The worms that could evolve and were introduced to fixed bacteria had a lot of sex for a short amount of time, but soon, their numbers fell to their original state. I do not understand why that is the case. If the worms could evolve, wouldn't the worms build up an immunity from that fixed strain. Perhaps a new parasite strain formed, causing the numbers to drop. Whatever the case may be, this article has piqued my curiosity of genetics and natural selection. I am looking forward to learning more about these topics.
I find this experiment very interesting because at first I too believed that asexually reproducing organisms would be dominant over sexually reproducing organisms. Since asexual organisms do not require a partner to reproduce I now realize that their DNA cannot adapt to changes in the environment. Conversely, sexual organisms can since they have combined DNA from two different organisms instead of just one. I liked how this article explained this reason through the hermaphrodite worms. The asexual worms would not be able to evolve in the presence of a parasite since their DNA is only a copy from its parent and cannot adapt to the change. However, the sexual reproducing worms would be able to evolve in the presence of a parasite since they can adapt to the change.
I've really never thought about this subject ever. It's really interesting how scientists and biologists are intrigued with such an uncompelling and unknowningly spoken topic. I wonder if they have a preference of what will do better for evolution. Then again, even though asexual reproduction has many benefits such as, not requiring a second partner, which, in fact, is quicker and much easier, i think it's rather cloning instead of rather having an amounts of genetic diversity. This, I'm guessing, is strongly required to produce new gene combinations to avoid parasites and remain prevelence. As sexual reproduction can greatly reduce the chances of mutations, asexual, however, cannot and all offsprings would get that disorder. In order to maintain their survival and existence, it's better off to effectively fight off parasites by shuffling genes that will be harder for parasites to adapt to, since parasites are now influencing on evolution, which the article says. As enough said, sexual reproduction can improve chances of surving in constantly changing enviroments and being adaptive of what nature has thrown in.
Although Carl Zimmer states that the research biologists have been conducting over the years "seems like a huge waste of effort," the results from the experiments he provides later in his article proves just the opposite of his claim. The two experiments described yield results that support the Red Queen theory so well that it may be a breakthrough in research. Even though asexual organisms already have all of the necessary genetic information to reproduce by themselves, sexually reproducing organisms have the benefit of genetic variation which allows them to evolve to build a resistance to parasites. It is interesting to me how the evolution of the bacteria and the worm in the experiments is relative; as the worm evolved to resist the bacteria, the bacteria responded by becoming a deadlier strain. Without change or genetic variation, the bacteria easily overtook and devastated the once thriving asexual population, an example of the boom and bust cycle. This article forced me to think about how parasites and sexual reproduction, two things that I thought were completely unrelated, actually relate to each other. Without parasites, there would be little reason for genetic variation to exist as it does when organisms reproduce sexually.
After reading this article, it confirmed my thought and the hypothesis of why sexual organisms are the dominant species. I knew that because of the structures of asexual organisms, they would be unable to recombine their genes and have a harder time to adapt to the parasites.
It was interesting to read the experiment done by the scientists at Indian University because it not only proved my original thoughts, but it also provided support for the (difficult to test) Red Queen conundrum.
Before reading this article I honestly knew nothing about asexual animals. While reading the first paragraph the question was set in my head, why haven’t asexual animals taken over the sexual animal if they have some many advantages? As I read about the red queen conundrum it all became clear to me. The reason that sex is so important is that is doesn’t allow parasites to grow and thrive since genes are mixed around in the sex process into new combinations that the parasites just can keep up with. The experiment with the worms supports that theory because the sexual worms live more in a parasitic area then the asexual worms. Overall the article was very insightful and game me a completely new view for sex.
Before even reading the article, the first thing that popped in my mind is the mental effects of sex; that it could relieve stress. Then I got myself thinking that psychological benefits are definitely not the reason why sex is more prevalent. If anything, it should be the physical effects that would help sexual organisms climb up the ladder of natural selection. So finally, I couldn't wait to read the explanation.
The first part of the article kind of confused me because why would sexual reproduction beat asexual reproduction if the latter already consists of many pros while the former seems like it just uses up a lot of energy?
In reading the article to its entirety, especially the Red Queen hypothesis, I've learned that with sex, organisms are able to rearrange their genes to the point that parasites are unable to dominate them, unlike in asexual reproduction wherein organisms do not have the ability to rearrange their genes to fight off parasites.
Before reading the article, parasites were last thing that I thought would be the reason for organisms to have sex. At first, the simplicity of the asexual organisms seemed better and less complicated however, it is because of the simplicity of their genetic combination that parasites easily adapt and quickly destroy these strains. On the other hand, although the genetic combination varies in sexual organisms making it more complex, it also saves these strains from destruction. The parasites cannot easily adapt to new genetic combinations of sexual strains.
The Red Queen theory explained in the article is interesting because it clearly demonstrates the concept of the "survival of the fittest" and how organisms constantly fight one another to survive. Asexual organisms may have more benefits than sexual organisms but because of parasites, they can never be the strongest strains.
I found this article very fascinating. Sex has to exist for generation after generation to occur. What would happen if sex never existed? well none of us would be here.
I think that as the study shows, sexual reproduction is a necessary part of evolution. The organisms that use asexual reproduction, in this case the worms, were able to survive, at a reasonable percentage, only if the bacteria did not evolve. However, if the bacteria was able to able to evolve, it, obviously, became a much deadlier strain of the bacteria. The asexual worms were not able to adapt to the changing bacteria whereas the the worms the used sexual reproduction, those that were more resilient to the new strain of bacteria were able to produce stronger offspring that would be resilient to the new strain of bacteria.
The Red Queen conundrum perfectly summarizes the problem that arises concerning the rise and fall of the populations of asexual and sexual reproducing organisms. You keep running and running but you stay in the same place. As the species continues to evolve, they seem to be moving forward, but they ultimately end up in the position that they began in.
The article was very similar to the way I viewed asexual and sexual reproduction. Although I was aware of asexual reproduction and of the way that it worked it was able to compete with those that used sexual reproduction. Because things are constantly evolving, any organism must adapt to its environment or be wiped out. An organism that uses sexual reproduction has a higher chance of surviving in such conditions.
On a side note: it must have been difficult for the scientists to incorporate all the different variables in the experiment. There are a variety of things that have to be considered in the experiment to prove, or disprove the Red Queen Conundrum. just a comment :)
I found this article on reproduction to be both very interesting and informative. I had always known that not all organisms reproduce the same way. Although i was already informed about other methods of reproduction, I was not however aware of any of the explanations as to why certain organisms reproduce the way that they do. It was interesting to find out that asexual reproduction has more advantages to sexual reproduction. I wonder if there are any advantages that go with sexual reproduction? Another thing that really caught my eye were the different experiments that were being taken with the worms. I personally found it very intriguing to see how scientists can manipulate aspects of experiments with different variables and such to retrieve different data. Overall I found that the concepts of reproduction with different organisms is very exciting and I would love to read and learn more about it.
I find this article to be interesting simply because I have never considered asexual reproduction versus sexual reproduction in terms of evolution. After reading the article I now understand that sexual reproduction is more prevalent in species in order to prevent being devastated from a newer parasitic strain. Asexual reproduction does not have this defense and so is susceptible to an evolved parasite. I find it interesting that the worms were so perfect to test this theory due to the fact they could reproduce both asexually and sexually. When faced with an evolving parasite the worms that sexually reproduced had a better survival rate than those that did not. This proves that sexual reproduction is prevalent in order to protect the species and will probably remain prevalent for a long time yet to come.
After reading, “Why is there sex? To fight the parasite army” by Carl Zimmer, I felt intrigued by the concept that evolution favors sexual organisms over asexual (since I initially thought that asexual organisms can evolve much quicker since they have control of when to fertilize and have the ability to generate carbon-copied offsprings). The question ….”Why sex?” has been prevalent in not only in the scientific realm; this question has been asked through the ages and still, ironically, is still not fully answered. Well, in this article, Carl Zimmer comes pretty close to explaining his observation and hypothesis on why sex is not only essential for species to evolve and continue to prosper but also the necessity of sex in order for species’ existence. After conducting an experiment which targeted the Red Queen theory, by examining the results of the sex life of a worm, scientists can conclude that evolution favors sex because it lets hosts fight better against parasites. The Red Queen hypothesis came to be commonly accepted as the mathematical model of how parasites influence the evolution of their hosts and vice versa. It only makes sense, having that partners go through cycles of boom and bust, that sexual organisms are able to avoid these dramatic cycles by shuffling their genes into new combinations, making them less vulnerable to parasites. Since asexual organisms subscribe to the host-parasite convolution occurrence, it is lucid that asexual strains do not have the tactic of preventing parasites from adapting; the Red Queen hypothesis restricts the asexual strains from developing. This concludes that sexual strains will always beat the asexual strains in development.
It is compelling however how the team of scientists at Indiana University was able to come to such a groundbreaking conclusion by only using tiny worms. Ultimately the conclusion serves to examine the results of the Red Queen hypothesis and how it proves that sexual organisms have a higher mortality rate than asexual organisms. Now that I look at it retrospectively (after reading the article), it is lucid that sex is necessary for evolution, since without this function asexual organisms would not be able to develop because of the stagnation in the strains caused by the Red Queen conundrum.
I found this article to be very interesting. Reproduction is important for not only to increase a specie’s population but also to higher the competitive advantage. It was a scientific way on why there is sex. Before reading this article I thought asexual reproduction would be more convenient, easier, and faster. However, after reading the article I learned the purpose of sex and how sexual reproduction is more dominant in evolution. It would make sense that asexual reproduction would win because the offspring arises from a single parent making it easier for living organisms to not worry about finding a mate. However, this article shows that sexual reproduction helps fight off parasites. I find sexual reproduction to be like a math problem. Genes from both parents have a greater variety of genes and a greater probability to be less vulnerable to parasites unlike asexual reproduction which only gets genes from one parent.
I never really thought about how important sex is for survival other than the obvious reason of reproduction. Carl Zimmer makes excellent points in his reasoning of the continued existence of sexual reproduction even though asexual reproduction seems better in theory; I especially found the Red Queen hypothesis to be intriguing. The hypothesis points out the fact that adaption is necessary in order for a species to survive parasites in its environment. Because the offspring of asexual organisms lack the ability to adapt genetic qualities favorable for survival against harmful situations or beings, sexual organisms clearly hold an advantage and prove why sex still exists.
This article has cleared a very big misconception of mine. If you think about it, asexual organisms should be the winners of the evolutionary race. Scientists are constantly finding bacteria and other asexual organisms which have been existing since the beginning of time. So it obviously makes sense that they know how to survive. However, after reading this article it seems other wise.
Asexual organisms can be successful only for so long. Evolution is any species' greatest weapon against extinction. After parasites begin to attack, asexual organisms can virtually do nothing to protect themselves because they all have identical DNA. Sexual organisms on the other hand have advantage as the can mix there genes around in combinations that throw off the parasites. This makes it harder for the parasite to adapt and makes it easier for the host species to survive.
Therefore, what seems most likely turns out to be what actually isn't happening. Sexual organisms have a better chance at evolving to beat out parasites where as asexual species have difficulty doing this. Even though sex seems like a waste of effort and time, it is because of this that a ton of sexual species have survived so long and evolved as opposed to asexual species.
This article was very interesting. It made me think of ideas that I never had thought of about sexual and asexual reproduction. I never really have thought of which type of reproduction would be better. But I figured sexual would be better because it would have a combined amount of traits whereas asexual there is only one set. This allows the organism to have better chances of survival therefore making the species continue. More traits allows the organism to maybe have a chance to have special characteristics that help it to survive such as in eating and escaping from predators. This is what this article has made me believe
After reading through the article, it is clear to see that sexual reproduction is favorable for survival in the world. It gives species an advantage since it can lead to many more changes in genes and would therefore be able to adapt quicker. Prior to seeing this article, I would have believed that asexual organisms would have the advantage since they did not have to look for mates and could have offspring that are almost a replica of its parent. However, now I can see that sex is favored in evolution from the experiment. The obligate selfing group, the asexual group, was the one that died off rather quickly in only 20 generations while the rest of the groups remained alive. Since these asexual organisms only receive a single set of DNA from one parent, it has a much lower probability of mutating. Sexual organisms receive a greater variety of genes from its parents and therefore a greater probability of evolution and adapting for survival.
This article made me think about where we as a human species would be if we reproduced asexually. Even though asexual reproduction seems better, it has the most disadvantages in the long run. Since asexual organisms make exact copies of their DNA, the bubonic plague, small pox, and polio would have wiped the human race out by now. There was no cure for the plague when it existed, the people that survived were just lucky enough to have the genes that provided some sort of resistance. This is an excellent example of natural selection. The humans with genes that didn't do much good just died off. The Red Queen hypothesis wouldn't affect us if we were asexual, because each strain of humans would be the same as the last. In the end, we can thank sexual reproduction for keeping us from becoming an extinct species.
Before reading this interesting article, I thought asexual reproduction would be favored among more species simply because it would be more convenient than sexual reproduction. However convience does not mean that asexual reproduction is better, as the "Red Queen" hypothesis stated that parasites can potentionally devastate asexual species. It is easier for parasites to adapt to asexual species rather than sexual species because asexual organisms do not have the ability to create new gene combinations, that otherwise, the parasite would have had to adapt to. An organism can avoid harmful parasites threatening its species by utilizing sexual reproduction. I never would have guessed that one reason why sex evolved was from parasites.
I also found the experiment at Indiana University to be appealing because the scientists used worms for it. The worms that used asexual reproduction were more devastated by the parasite in the experiment, which was a particular strain of bacteria, than the sexual worms were. This backs up the "Red Queen" hypothesis because only the asexual worms were affected by the parasite because the parasite did not have to adapt to new gene combinations that would have been present in the sexual worms.
http://www.sciencedaily.com/releases/2010/01/100121161238.htm
I found this article to be another good defense for why sexual reproduction will be more dominant than asexual reproduction (its a little old but the research still holds itself up.) According to the article, sexually reproducing organisms will accumulate harmful DNA mutations at half the rate of asexual reproducing organisms. So yes sexual reproduction will always have the upper hand over asexual reproduction there's no doubt about that; I just think that maybe there are other reasons behind the need for sex.
This article is very interesting in that it talks about sex in a very untraditional way. I initially believed that sex was just necessary for reproduction and passing on genes. But the article explains other reasons why sex is important for both survival and evolution. It talks about how it helps fight of germs and parasites. The Red Queen hypothesis is really interesting in how it compares asexual versus sexual organisms and how asexual organisms are not as strong a sexual organisms. At first it I felt that asexual reproduction would be less dictated by parasites and germs but the Red Queen theory makes sense because there is hardly any variation in genes in asexual organisms therefore making them more vulnerable. Whereas sexual organisms allows there to be a mix of genes which makes it harder for germs to dominate.
This article was very interesting in addressing the fact that offspring that are a result of sexual reproduction have a stronger defense against parasites compared to offspring of asexual reproduction. This is due to that fact that sexual organisms are able to adapt and fight different parasites, while the asexual organisms are defeated by the parasites.
Also I found it interesting that asexual worms would stop reproducing when introduced to co-evolving germs; however the worms exposed to non-evolving bacteria would continue to reproduce normally. In comparison the sexual worms exposed to evolving germs would reproduce continually, while the worms exposed to un-evolving bacteria would have a spike in reproduction but eventually be brought back to normal. This experiment further proves that sexual organisms are more influencing because of their ability to change with the environment and continue to produce future generations, while asexual organisms are unable to adapt to the changes and eventually reproduction stops completely.
This experiment further proves that sexual organisms are more influencing than asexual organisms because of their ability to change with the environment and continue to produce future generations, while asexual organisms are unable to adapt to the changes and eventually reproduction stops completely.
I just came across the lottery principle. Some of you might find this interesting - it ties in to this article really well. It essentially says that ‘…[a] sexual form of life will reproduce at only half the rate of an equivalent clonal form. The halved reproductive rate of sexual forms is probably made up for by a difference in quality: the average sexual offspring is probably twice as good as an equivalent cloned offspring.'
Ridley, Matt, The Red Queen Viking, London, p. 254, 1993.
Before reading this article, I had always thought of sex as being only an essential part of reproduction. Many scientists and researchers have always stated that asexual reproduction was more productive than sexual reproduction. However, according to this article, that is not always the case. Asexual reproduction is very efficient and productive, but the products are always exactly the same. On the other hand, sexual reproduction maintains genetic diversity. This aids in the fight against parasites because the combination of genes differ from organism to organism. Altering the combination of genes makes it more difficult for the parasites to adapt to each individual organism. In asexual reproduction, the organisms are all identical to one another, which makes it easier for a parasite to infect them. As the experiments show, the worms sexually reproduce more frequently when there are parasites so it is harder for the parasites to assimilate themselves with the organisms being produced. In conclusion, sexual reproduction is very important for the survival of many organisms and it is more important than many people see it to be.
Prior to reading this article, I was clueless as to how sexual reproduction can be effective towards evolution. I had no understanding of what benefits sexual reproduction had over asexual reproduction, and if there were any at all. However, since reproducing sexually seems to be more prevalent in today's society, I knew that there had to be a specific reason. This article explained everything. Asexual organisms are more vulnerable to parasites and that's why their mortality rate stands out compared to sexual organisms. Since sexual organisms are able to shuffle their genetic code, it's a lot more difficult for parasites latch onto their hosts.
The way scientists found this out was quite fascinating as well! Testing out the red queen hypothesis was done by utilizing hermaphrodite worms, since they are able to reproduce both sexually and asexually. By pairing these worms with the parasite "Serratia marcescens" I and many others were able to fully comprehend this concept.
I never really thought about this subject with much interest, but after reading this article it has made me realize that asexual reproduction is not as efficient as sexual reproduction. In asexual reproduction, the organism does not need a mate to reproduce which might seem efficient, but with asexual reproduction the organism would not be able to evolve. I would have never thought that sexual reproduction was more efficient because of parasites. In sexual reproduction, organisms need mates to reproduce which helps them evolve. In sexual reproduction the genes of the two mates are combined to form the embryo. The embryo would then have a different gene structure compared to its parents. Sexual reproduction is more efficient because parasites have a harder time catching up to their hosts. They have a harder time because of evolution.
I did not know that sexual reproduction was better than asexual reproduction. I always considerded asexual reproduction more suficient because one does not require another math to make an offspring. After reading this artical I realize than some scientists have tested a theory where sexual reproduction is more efficient. In asexual reproduction there are less complication and it can be proformed anywhrere at anytime but the offspring will be the same and will not have any mixed or different genes because there was only one parent. Sometimes thats dangeous because it makes it easy for the parasites to take control over the organism and kill it. While in sexual reproduction the genes tend to change and get mixed up so sometimes the parasites cannot harm the organism. The parasites can adapt to one kind of genes which is what asexual reproduction comes with but when the genes are mixed and matched in many different ways parasites have a harder time curpting an organism with mixed genes. In the long run sexual reproduction is esentional for a species survival and its a big step towards evolution.
Hi everyone. I thought this was a very interesting article. As stated in the article, one would assume that asexual reproduction is more beneficial to a species survival, since all members of the species are capable of reproduction, as opposed to just the one half in species that require sexual reproduction. However, the experiment explained in the article showed this is not necessarily true.
In the experiment, worms that reproduced asexually suffered from much higher mortality rates than worms who reproduced sexually. The reason for this is because sexual reproduction diversifies the gene pool of a species, making it harder for bacteria to adapt to a species and infect it. However, asexual reproduction does not diversify the gene pool, making it easier for bacteria to adapt to and infect a species.
In the end, sexual reproduction is much more efficient in the survival of a species than asexual reproduction.
“Why is there sex? To fight the parasite army.” I learned that sex is not only essential for reproduction, but it is important to fight off bacterias and parasites as well. I had always thought that asexual reproduction would be more sufficient than sexual reproduction. Before reading the article, I had never thought about sexual vs asexual reproduction and how it would have different affects on society. After reading this, I found it interesting that a group of scientists in Indiana University had come to such a conclusion using small worms. The Red Queen Hypothesis helps explain mathematically the influence of parasites in the evolution of their hosts. It also helps explain how sexual reproduction helps each strain improve than the last. In conclusion, sexual reproduction seems to be the most sufficient way to reproduce and is important for our survival along with many other organisms.
This article was very interesting, especially since it talked about how sexual activity is affected by evolution. I would only think that the environment had a major effect on whether an organism would be able to reproduce, not whether the a certain parasite that infected the organism involved. The experiment shows why it is important that crossing over is done during meiosis. Crossing over allows evolution to occur because it increases the chances of an organism surviving, because it might have obtained the gene to be resistant to the gene. Then the organism will mate and most likely the trait will be passed on. This can only be done during sexual reproduction.
Another part that I found interesting was the fact that these two species, the worm and the bacteria, were so dependent on each other. I would never have thought that a small bacteria would be the problem for a decrease in a population of worms.
This article provides a very thorough and reasonable explanation for why sexual reproduction is so dominant among our world's organisms. When I read the title of the article I would've guessed that perhaps because sex provides something pleasurable, it motivates sexual organisms to reproduce and in turn results in a higher rate of proliferation than asexual reproduction. However, it seems my hypothesis was quite far from the results these biologists obtained.
With asexual organisms, a mostly identical set of genes is passed down generation by generation - As their genes remain mostly the same, this essentially provides a step-by-step instruction manual for evolving parasites on how to destroy them. Within a few generations, parasites could decimate an entire vast population of asexual organisms. On the other hand, with sexual reproduction, there is far more genetic variance. With each generation, there are many different combinations of genes that are shuffled together. Because of this, the population can adapt to become more resistant to the ever-changing parasites. This whole concept was interesting enough to a computer techie like me, as it's just the same way an unlawful hacker would hide from the authorities - by constantly switching up security measures and encryption methods.
Cool article d00d!
Sexual reproduction definitely has its benefits such as endlessly avoiding the attacks of parasites by evolving genes as the article describes. While I do agree that this is a very helpful trait of sex, I do not believe that this is the reason it exists. Sexual reproduction is so prevalent in so many species because it allows for evolution to act quickly and efficiently. As the experiments at Indiana University observed, when the bacteria was able to co-evolve with both sexual and asexual worms, the sexual worms suffered lower mortality rates from the parasite. Sex allowed the best genes for avoiding the wrath of the deadly Serratia marcescens to survive while "obligate selfing" kept reproducing the same genes that were susceptible to the ever-stronger bacteria. The advantage of sexual reproduction lets the best genes for adapting to an environment thrive, or simply put, evolution, survival of the fittest. It can apply to other environmental advantages besides surviving the parasites described here, like the fins and gills of a fish adapted for water or the legs and hands of a human for land. The benefit of sexual reproduction must be important to life since most complex beings do have sex.
P.S. Codes and Keys is a great album, and if I wasn't learning a new crochet stitch on another blog, I probably would've forgotten to post on this one. LOL. Hope your summer's going well Dr. H!
To be honest, I never thought about the benefits that come from both asexual and sexual reproduction. After reading this article, I was able to confirm that sexual reproduction is more efficient. Even though reproducing asexually is faster, easier, and can be done without a partner, asexual reproduction cannot protect organisms from parasites the way sexual reproduction can. Their gene structures would always remain the same, leaving them vulnerable to parasites and unstable when changes in their environment occur. Organisms that reproduce sexually, however, shuffle their genes allowing the offspring to become more resilient against parasite threats.
I thought it was interesting to find out that parasites are of paramount importance to why organisms have sex and evolve. Another thing I found interesting was the fact that hosts and parasites could coevolve with each other as each go through their cycles of boom and bust. In the experiment with the worms, the soil parasites grew stronger after the worms also evolved into a stronger organism; This supported the Red Queen hypothesis perfectly. After all the knowledge gained on this topic, I disagree with the author's opinion that puzzling over this topic is "a huge waste of effort." Clearly, the information gathered from research is important to the study of biology.
It is surprising to find out that asexual reproduction is not more prevalent in organisms than sexual reproduction, being that an asexual organism can produce offspring of their own. So why is there sex?- the answer is to fight the parasite army.
The article explains that reproducing sexually is more common, the main reason is that asexual organisms are more susceptible to parasites which destroy the host strain. Sexual organisms however, can avoid this “boom and bust” by creating new combinations of their genes, making it harder for the parasites to consume the host.
Indian University did an experiment of the Red Queen hypothesis using hermaphrodite worms and presented these worms with the parasite “Serratia marcescens” . Scientists used this type of worm because the hermaphrodite worm produces both sexually and asexually. The experiment showed that the asexual organisms that co-evolved with parasites were annihilated over several generations; whereas, the sexual organisms coevolving with the parasite had a far better record of survival. Furthermore the author explains that the host of asexual reproduction will die out sooner, but in sexual reproduction, the host has a much lower mortality rate.
According to this article, it is clear that sexual reproduction has many advantages over asexual reproduction. Although many species reproduce asexually, they are not as successful as sexually reproducing species. This is the why most sexually reproducing species are generally more successful and are in a higher position in the food chain. As stated in the article, sexually reproducing species are much more successful in fighting off parasites and viruses, allowing them to continue reproducing which is essential for the survival of the species. Asexual organisms are much less successful in fighting off diseases making it harder for the species to survive. The ability to evolve is also extremely important for the survival of a species. Asexual reproducing species are much more vulnerable to their changing environment and to new diseases and viruses because they are unable to evolve. Sex is necessary for the survival of a species and for the species to adapt to the changing environment.
So from what I got out of this article was that sexual reproduction is more ideal and beneficial when it comes to offspring adapting, and building a stronger genetic code for the environment they are required to live in. What surprised me is how important sexual reproduction vs. asexual reproduction is when responding to parasites. Since asexual organisms have basically the same structure, if the bacteria harms one, it harms them all. Where as in sexual organisms, their DNA is so unique, all the reactions to the bacteria could be different! Sexual reproduction is clearly more dominant of the two.
While reading this article I found out a lot of things that I didn’t know. First off I had no idea that sex was due to parasites. Natural selection favors parasites even though they kill off hosts and allow a new strain to dominate. Also I initially thought of sex as a way for different species to reproduce and to pass genes on but I before reading this article I would have never considered it as a means of survival. Finally this article taught me about hermaphrodite worms. They can fertilize their own eggs with their own sperm. It was pretty interesting how Caenorhabditis elegans are either male or hermaphrodite.
It is quite interesting to study from a biological standpoint why sexual reproduction is favored over asexual reprodution. One might wonder, if a mesaure of evolutionary fitness is the number of offspring an organism passes on to the next generation, why not favor asexual reproduction, which tends to happen more frequently? The key is the genetic variation that sexual reproduction offers, as this article discusses. While the only source of variation from parents to offspring is mutations for asexually reproducing organisms, mutation is miniscule compared to the recombination of alleles from parents to offspring as a source of variation in sexual reproduction. Because of the different combinations of alleles that are introduced into the gene pool via sexual reproduction, natural selection can occur, and it is more likely for some of the organisms to have the genetic code to resist parasites. In essence, although asexual reproduction may beat sexual reproduction by miles in terms of the number of offspring, sexual reproduction offers the evolutionary advantage of different genotypes.
The Red Queen Hypothesis summarizes this idea. Adaptation is needed in order for a species to withstand other coevolving species (such as parasites). Asexually reproducing species are always more susceptible to parasites, particularly those that sexually reproduce, even when the species are reproducing greatly. There is even experimental data supporting this idea. Sexually reproducing C. elegans developed greater resistance to soil bacteria than did asexually reproducing worms, which were wiped out in 20 generations. On the whole, this article is extremely intriguing, as it forces the reader to ask why certain things about life are the way they are. The article reflects in a general sense on the power of science to describe even the simplest observations about life.
I found this article very interesting. I was surprised to find out parasites are essential to reproduction and evolution. I always wondered why organisms that reproduce asexually haven't been able to evolve like other organisms. The Red Queen hypothesis was very insightful, showing that when parasites build up, asexual strains are disrupted while sexual strains make it harder for parasites to adapt, which give the egde to organisms that reproduce sexually.
After reading this article, I was impressed with the manner in which Carl Zimmer presented his argument. The fact that sexual reproduction continues to prevail over asexual reproduction is confusing even to some scientists. I think Zimmer's references to the Red Queen conundrum and related experiments make his point much easier to understand. Before reading this article, I too assumed that asexual production was far more efficient than sexual reproduction. When approaching the issue from a logical standpoint, asexual reproduction appears to be the better of the two because it allows for self-sufficiency. However, I never really considered the importance of genetic diversity, and I think this article effectively affirms its significance. Although asexual reproduction may allow an organism to yield more offspring without the help of another organism, it does not allow for any genetic diversity within the population. The help of another organism may actually not be a bad thing when one considers evolution in response to parasites. When two organisms reproduce using sexual reproduction, their offspring inherit genes from both parents. Even if one parent is not genetically equipped with the ability to resist a certain parasite, the other parent might be. This is incredibly important, because the population has the potential to evolve in favor of the trait that allows for immunity to the parasite. A population of organisms that reproduces sexually is genetically diverse, while a population that reproduces asexually essentially consists of genetic clones.
When one considers the fact that asexual reproduction deprives a population of the ability to evolve in response to external hazards (such as parasites,) it seems far less efficient than it first appears to be.
Hi Dr. H! Before I start my comment I would like to apologize for the tardiness of my messages. I will get all of the blogs commented on before school starts. Before the school year ended I was not positive I would be taking apbio and when I found out I was I was not able to get on the site. I attempted to email both you and Ms. Drust but of course when I tried the email servers for the school were down. Again, I apologize.
On another note, I found this article on "Why is there sex?" very informative. Obviously reproduction is a way of life for all species in the world, however it never occurred to me that asexual reproduction could have such a downfall. Reproducing with the same genes, over and over again for generations creates a weak specimen. This allows bacteria and parasites to become accustomed to the strain and be able to take it over. Sexual reproduction leads to different mixes and combinations of genes which makes a parasites job more difficult. If bacteria are able to evolve and get stronger over time, a specimen that does not change will become very vulnerable. The Red Queen hypothesis explains this very well. It shows that asexual and sexual strains can never compete and that sexual strains are clearly the more effective reproduction method.
I found this article very interesting because I had always wondered why organisms would prefer sex when reproducing asexually is more convenient and easier. After reading about the experiments conducted by the team I finally understand the reason for sexual reproduction. It provides a much needed genetic variation in the offspring. This genetic variation is key to the survival and success of the species because, as stated in the article, parasites and diseases can wipe out a significant portion of a population that only has minor genetic variation. But with greater genetic variation you allow for your species a greater chance since the virus will have different effect on each organism. This article also reminded me of freshman bio and the term "crossing over". I believe this term is related to sexual reproduction because both involve the reshuffling of genes to produce genetic variation
Asexual reproduction allows a species to develop and further complicate it's genetics. Thus, making it difficult for bacteria and parasites to invade it. On the other hand, asexual reproduction causes bacteria to come to see the species as normal and prone to invasion. This article shows that sexual reproduction is much more advantageous than asexual reproduction.In reading this article sexual reproduction illustrates its numerous advantages.
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