Parthenogenesis: no dad needed

Parthenogenesis

Chiloscyllium plagiosum

The white spotted bamboo shark has surprised ichthyologists (fish biologists) by doing something unexpected: a second generation of fishes reproducing without a male parent. This strange, sci fi-like way of reproducing is known as parthenogenesis.

The following passage is via New Scientist:

Some animals, including Komodo dragons and domestic chickens, can sometimes produce offspring without copulating with a male. Females do this by using one of two methods to add an extra set of chromosomes to their eggs, producing either full- or half-clones of themselves. It had only been seen in captivity – until two virgin births were recently recorded in a wild sawfish and pit.

It was previously thought that parthenogenesis was extremely rare, occurring just once in a blue moon (especially in vertebrates). These findings show that reproduction without a male parent is much more common in nature than previously thought.

Food for thought (Answer and explain questions for extra credit)

Would the mother be considered haploid or diploid? Can parthenogenesis occur with high order vertebrates such as mammals?

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34 thoughts on “Parthenogenesis: no dad needed

  1. The mother, in this case, would be considered to have diploid cells since this means that the organism has paired chromosomes, one from each parent. Based on the definition of parthenogenesis (a type of asexual reproduction in which the offspring develops from unfertilized eggs), this can’t happen in the case of mammals because they have imprinted genetic regions where either the maternal or paternal chromosome is inactivated in the offspring in order for the development to occur normally. A mammal created by parthenogenesis would have double the amount of maternal genes and a lack of paternal genes which will later on result in abnormalities. Scientist can artificially induce parthenogenesis but the embryo will not develop correctly and will not be able to survive.

    http://bioteaching.com/parthenogenesis/

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  2. Well, this is quite interesting.

    Please refer to the paper Mr. Adrover linked in the post (http://onlinelibrary.wiley.com/doi/10.1111/jfb.12862/abstract).

    The first thing to note about this is written in the abstract of the paper. The female reproduced asexually, so we would expect all offspring to be female. Well, this was not the case. As it was stated, one offspring showed characteristics that pointed it to be closer to the male gender than the female. However, upon further inspection (the dissection), the scientists observed that the sexual organs in this animal were either deformed or absent. How could this be? And how could this even happen through asexual reproduction from a female?

    The answer is simple: The offspring had no true Y chromosome. I say “true Y chromosome” because it had male sexual organs, and this implies there was some sort of expression from a prototype Y chromosome, perhaps from an improvised SRY gene. The way this could have happened is that as the mother added the necessary pairs of chromosomes to her eggs, a mutation–either planned or spontaneous–in any of the X chromosomes resulted in an altered sex chromosome that was more similar to a Y chromosome and carried codification for masculine expression, hence the male having an X”Y” combination.

    With that addressed, another question arises. If the mother reproduced asexually and gave birth to both females and males, are the offspring true haploids or true diploids? We find the answer in the post’s main quote: “Females do this by using one of two methods to add an extra set of chromosomes to their eggs, producing either full- or half-clones of themselves.” This implies that the offspring could be both diploid or haploid. Again, how?

    Let us look at it this way. If the extra set of chromosomes that the mother added to the eggs was an exact replica (no mutations, no crossing overs, no genetic mishaps) of the set already present in the eggs, then the zygotes would develop into embryos with two sets of the exact twenty-three chromosomes–a true haploid organism (there is no genetic variability between each homologous chromosome). However, if the extra set of chromosomes added was in any way distinct from the set already present in the eggs–even if it is a small mutation, such as the possible SRY mutation in the X chromosome of the male offspring–the chromosome sets in the egg would not be identical, and so the organism would be a half-clone of the mother–a semi-diploid organism.

    But yet again, this raises another question. What about the mother? Is she a true diploid or haploid? In reality, there is no way to determine if the mother is a diploid or haploid without first consulting its genetic factors and parents. What if the mother is a parthenogenetic offspring herself? And if she was, would she be a true haploid or a semi-diploid as in the case above? Or what if she had a male and female parent and was truly diploid? Perhaps the answer is in the full paper, but unfortunately we cannot pay to see the rest of the article, and so this question remains unanswered to us.

    Moving away from fish, the possibility for asexual reproduction in any of the phylums in Animalia is probable thanks to modern science. However, this does not imply proper development or even survival. As Neian Contreras excellently said in his post, manually inducing mammalian zygote development through the use of an exact clone of the set of chromosomes in the mammal’s egg would result in either no formation of an embryo, developmental abnormalities, and/or early death. It all has to do with perspectives. Put short, mammalian asexual reproduction is possible at the biochemical and molecular level but not at the organismal level.

    In conclusion, such a scientific observation can only be explained by mere genetic chance. This sort of asexual reproduction, even though considered favorable in the paper’s abstract, still has its consequences. In the first place, we observed how the male’s reproductive system was abnormal, and perhaps all of the offspring’s bodies were not entirely correct, maybe due to this type of reproduction similar to inbreeding. Finally, it is not certain whether the offspring of a parthenogenesis will be identical to the parent or not–it all depends on the parent’s methods for asexual reproduction and the mere chances of genetic variability during the processes of meiosis.

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  3. The study of parthenogenesis in the wild is extremely complex due to the fragility of the organisms. Nonetheless, with the technology advancing at an impressive rate the possibilities of understanding this marvelous, yet weird, process grow bigger every day. The mother in this case is definitely a diploid, nevertheless for this reproduction to take place it must have replaced the “male” genetic contribution with an exact copy of her own. This can be concluded from the fact that only diploid cells have a chance of developing, although suffering from some major abnormalities. In the wild, this type of reproduction cannot be performed in high order vertebrates such as mammals, but after various years of study scientist have induced it is small (simpler) organism like rats and rabbits. This has resulted in extreme abnormalities because they possess two X chromosomes.

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  4. It’s very interesting that sharks and other vertebrates can reproduce without the male chromosomes. Parthenogenesis was discovered by Owen in 1849 in his book called “On parthenogenesis or the successive production of procreating animals from a single ovum”. Some scientists wonder if mammals (especially humans) can do this reproduction. The answer is no. In mammals, some genes need to be completed with the male chromosomes (sperm). This statement has been proven by experiments on rabbits (bioteaching.com>parthenogenesis25dic2010). The experiments concluded that parthenogenesis is not possible in mammals.

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  5. Many species have done parthenogenesis, a reproduction where a female gamete develops a new individual without being fertilized by a male gamete. In some parthenogenetic species, egg cells don’t undergo meiosis before dividing into new cells or two egg cells fuse after meiosis. In the link below, I found a website where they studied in 2015 species who have done parthenogenesis and found many cases in snakes, sawfish, lizards, and stick insects. After reading about parthenogenesis, I would consider the mom to have diploid cells in order for the organism to have the chromosomes it needs. Unfortunately mammals and parthenogenesis can’t go together and this is because the offspring would result with irregularities from lack of paternal imprinted genes.

    http://www.bbc.com/earth/story/20151216-virgin-births-are-happening-everywhere

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    • Keep in mid that if the fitness of a population of parthenogenetic species is threatened, then the genetic switches in the organisms genome will turn on, allowing it not to need a male for reproduction. What environmental events (aka: natural selection) drove these species to do this? I think this is a very intresting problem in Biology, one whose investigation might prove useful for humans in the near future.

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  6. Parthenogenesis is a form of reproduction in which an unfertilized egg develops into a new individual, occurring commonly among insects and certain other arthropods. In regards to the questions asked, the mother would have to have diploid cells since the organism has paired chromosomes because of the parents. There is no known example of a mammal undergoing parthenogenesis, either in captivity or the wild. But in the 1930’s at Harvard University, a scientist, Gregory Pincus, started investigating the reproductive systems of mammals. His work later helped him in co-inventing the human contraceptive pill. Researchers say that it remains highly unlikely or perhaps even impossible, for a single mammal to naturally produce viable offspring, due to fundamental aspects of their biology. In regards to insects and anthropoids, parthenogenesis occurs more times naturally than expected; it was believed that it happened once every blue moon. Scientists are still not sure why this reproduction happens, but they do know that parthenogenesis raises fundamental questions about the importance of sexual reproduction.

    http://www.bbc.com/earth/story/20141219-spectacular-real-virgin-births

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  7. The reproduction that doesn’t include the male parent is called parthenogenesis. In my opinion, I consider the mother to have diploid cells in order that Parthenogenesis can occur.
    There are two types of parthenogenesis. One is called the apomixes, in which the female sex cell replicates by mitosis. These two cells are diploid cells. The other case is automixis. In this process, the egg cells are produced by meiosis. However, the egg cell doesn’t need a male cell to become diploid.
    The mammals need the dad and the mom to reproduce no matter what. However, there was a discovery that challenged this statement. In the year 2004, an experiment was conducted with a mouse called Kaguya for the purpose of achieving reproduction without a male parent. In this experiment, they alter an egg cell to put it with another unchanged egg cell to create Kaguya. The modified egg cells and the normal egg cells are combined to produce the functional offspring. This experiment was an exception because it is not common and it is really odd that mammals reproduce without the male cells. The experiment of Kaguya was an unusual occurrence.
    In my opinion, I find this method of reproduction not correct for us humans. They would play with the ethics of human belief and also this is not our nature. In that case, we don’t know what implications it will have for the offspring.

    https://www.newscientist.com/article/dn4909-virgin-birth-mammal-rewrites-rules-of-biology/

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  8. Parthenogenesis is most simply defined as reproduction without fertilization. With this in mind, the mother would contain diploid cells, which means that she contains two complete sets of chromosomes, one from each parent. Parthenogenesis cannot occur within the high order vertebrates such as mammals because they need a set of chromosomes from the male sperm in order for development to proceed. There are no parthenogenetic mammals because certain genes will not switch on unless paternal genes are present. Nevertheless, scientists are able to artificially induce parthenogenesis unfortunately as a result, the embryo will die before reaching adulthood.
    This video shows a quick overview of parthenogenesis and it truly helped me in fully grasping this subject.

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    • We know that higher order organisms do not undergo parthenogenesis. But why do you think this happens? What evolutionary reasons might there be for a mammal not being able reproduce without fertilization?

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  9. In parthenogenesis, reproduction occurs when a female gamete develops without being fertilized by a male gamete. (it is referred as a type of asexual reproduction, but it is really not). This was discovered by Owen in 1849 in his book/monograph.
    In parthenogenesis, the egg becomes the only source of genetic material capable of creating an embryo. It can occur in many species but not in mammals, it can only be induced but the parthenote will not pass for more than a few days. As an example, the mother white spotted bamboo shark has to be diploid because it doesn’t depend on another diploid to reproduce, unlike haploid cells which require merging with another to reproduce. Parthenogenesis can occur in many plants, few vertebrates, invertebrates and can be artificially induced in mammals, but as said above, it wont go anywhere since the parthenote will die out.

    Links used:
    http://www.ansci.wisc.edu/jjp1/ansci_repro/misc/project_websites_08/tues/Komodo%20Dragons/what.htm
    https://www.newscientist.com/article/dn4909-virgin-birth-mammal-rewrites-rules-of-biology/
    http://bioteaching.com/parthenogenesis/
    http://www.diffen.com/difference/Diploid_vs_Haploid

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  10. Parthenogenesis is a highly interesting topic a way in which female organisms can reproduce without a need of a male. The mother would be considered a diploid since she would have paired chromosomes to replace the male chromosomes.Parthenogenesis would not work in mammals and even if the managed to develope a pair of its chromosomes the offspring would die or become abnormal and mutated. Parthenogenesis was first discovered in 1849 by Owen in his book. Where it was explained that parthenogenesis was when an egg is the only source of genetic information for the offspring. This process can prove to be disadvantageous because any diseases the mother was vulnerable, so would the offspring. In the end it also advantageous for the survival of a species as the female can reproduce asexually. In the end of the even tho humans cannot do parthenogenesis, it would interesting if one day it could be a possibility.

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    • Another parthenogenetic animal, via Wikipedia: “The asexual, all-female whiptail species Cnemidophorus neomexicanus (center), which reproduces via parthenogenesis, is shown flanked by two sexual species having males C. inornatus (left) and C. tigris (right), which hybridized naturally to form the C. neomexicanus species” null

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  11. Parthenogenesis might as well be called natural cloning. Parthenogenesis is when a female produces an egg with a full number of chromosomes (diploid), making the offspring exactly like the mother. Although studies show that parthenogenesis is not so rare or harmful for reptiles, fish, and even amphibians, it might not be the best choice for mammals. The reason for this is that in order for the offspring of a mammal to develop correctly, it must have genes from both the father and mother for the embryo to grow. Other animals have the same type of genes in their chromosomes, therefore gender doesn’t make a difference in reproduction. In mammals the sperm doesn’t have all the necessary genes nor the egg, they need to complement each other to make a whole in a process called imprinting. Although parthenogenesis has been artificially done on mammals, the offsprings are usually defective because they lack the proper functioning of its genes.

    https://www.newscientist.com/article/dn4909-virgin-birth-mammal-rewrites-rules-of-biology/

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  12. Parthenogenesis is most simply defined as reproduction without fertilization. More specifically, it occurs when a female gamete develops a new individual without being fertilized by a male gamete. It is often called a form of “asexual reproduction,” but it is more accuratley defined as an incomplete form of sexual reproduction. This is because it involves the production, activation, and development of a female egg which is a specialized reproductive cell. I would definitely consider the mother a diploid because she replaced the missing male chromosome with one of her one. This type of reproduction is not common in nature and only has occurred with some fish and amphibians. It is said that if this type of reproduction were to be tried on high order vertebrates like us mammals would result in abnormalities in the offspring due to that they lack proper gene function but who knows if in the future mammals will be able. Here is a link of a news article that a mouse was created with parthenogenesis

    https://www.newscientist.com/article/dn4909-virgin-birth-mammal-rewrites-rules-of-biology/

    Maybe if with the help of science and technology we could perfect this process and this method could be used in humans to help mother conceive their own biological children without having to need a partner.

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  13. Parthenogenesis is actually beneficial for the species that undergo it. Since these species do not need a mate for sexual reproduction, they save more energy and time not looking for one, plus the fact that its offsprings will have more of its genes than if there were two parents. Parthenogenesis also prevents more easily for the specie to become extinct, and it allows it to populate a new area within a short period of time compared to if it depended on sexual reproduction. http://everydaylife.globalpost.com/benefits-parthenogenesis-33835.html

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  14. This is an amazing discovery, but it is a bit scary as well, knowing that men are becoming more and more useless as time passes. I’ve heard of reptiles doing this, but I have never heard about a shark that is able to reproduce this way. This method of reproduction might have some advantages and disadvantages in nature. I believe that one disadvantage with this method of reproduction is that less mutations might occur since only one animal is required for it to take place. I also believe that less mutations might cause a disadvantage in nature and might lower the animals chances of survival. An advantage might be that the animal doesn’t have to find a partner.

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  15. This is an example of how a species can survive despite having the odds against its favor. Without having a male around so that it can reproduce, the female undergoes parthenogenesis, which is the process of reproducing without a male partner. It is interesting to know this because other species can also start to undergo parthenogenesis since evolution is always taking place and finding new ways for species to evolve. This means that females from different species does not have to be always dependent on the male counterpart for reproduction. This can also answer if the mother is a haploid or a diploid. It is a diploid because in order to reproduce without a make, the mother had to replicate the full set of chromosomes into the egg in order to replace the chromosomes that the male is supposed to give, making the offspring (also a diploid) almost identical to the mother (this may explain why it isn’t considered as an asexual reproduction, but as an incomplete form of sexual reproduction) .

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  16. If you need solid evidence that evolution exists, you would probably be best going with this example of parthenogenesis. in my opinion i believe this is a more efficient way of reproducing. it’s faster and there is no need for a partner. i just thought that what if there was a species of animal that was an endangered species but there isn’t a male around in order to reproduce? this process could ssave that organism and it’s extinction and keep reproducing until there isn’t not even 1% possibilty of it dying out. if this ever became possible in humans it would change the world and nature in every aspect. it would also be dangerous considering there may be an excess in the amount of organisms produced. it really allows you to think of many possibilities and to literally believe, anything is possible.

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  17. It is amazing how species evolve. Parthenogenesis may have been a mutation that allowed an organism to have all the chromosomes needed for reproduction. Scientists are discovering that parthenogenesis occurs in many different species; amphibians, reptiles, fish, and birds. The mother would be a diploid because it needs to have all the chromosomes needed for reproduction. All though other vertebrates have performed parthenogenesis, it seems like mammals cannot. For more information on species that perform parthenogenesis: http://www.bbc.com/earth/story/20141219-spectacular-real-virgin-births

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  18. I never acknowledged that the process of parthenogenesis was an extremely common process, until I read this post. Parthenogenesis has been a fascinating discovery for human kind. The fact that certain female organisms have the ability to reproduce without the presence of a male figure is impressive. The question is, will the organisms with these capabilities transmit them, through the process of genetics to other organisms, in order for this method of reproduction to evolve? Evolution is an important term in science, because it represents change and how organisms might evolve in the future. In the process of parthenogenesis, a female gamete develops a new individual without being fertilized by a male gamete. The organism that the female reproduces is considered to be a type of clone. Genetic fingerprinting was used to identify parthenogenetic offspring produced by two female Komodo dragons that had been kept at separate institutions and isolated from males.
    http://bioteaching.com/parthenogenesis/

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  19. Parthenogenesis is the reproduction that involves development of a female gamete without fertilization. It occurs commonly among lower plants and invertebrate animals, particularly rotifers, aphids, ants, wasps, and bees. An egg produced parthenogenetically may be either haploid or diploid.It is actually beneficial for the species that undergo parthenogenesis since these species do not need a mate for sexual reproduction, they have more energy and time not looking for one.

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  20. Parthenogenesis is a very interesting subject. The fact that some animals have the ability reproduce without the need of a male is amazing. It might not be possible in high order vertebrates, like mammals, yet. However, it could be possible that this changes maybe thousands of years from now. Now, whether the mother is considered haploid or diploid depends on the type of parthenogenetic reproduction. If the kids are full clones of the mother, then the mother was probably haploid. If the kids are only half clones, then the mother was probably diploid.
    http://bioteaching.com/parthenogenesis/

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  21. Parthenogenesis is something very interesting and is definitely something that needs more importance. It tells us that females in the natural world won’t need a male to fertilize their egg cells. Scientists talk about how this can be studied to see if it might work with humans which if it turns out true it will go to show that males will be useless for reproductive purposes.

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  22. Parthenogenesis is defined as the process when a female produces an egg with the full number of chromosomes. With this definition, we can conclude that the organisms would be diploid and therefore be identical to the mother. Even though parthenogenesis has been proven to not be harmful in reptiles, fish and in amphibians, in mammals it’s not completely safe and is not considered to be the best choice. For mammal offsprings to develop correctly, it must have genes from both female and male parents for the embryo to grow and develop. Reptiles, fish and amphibians have the same type of genes in their chromosomes so gender does not affect reproduction. Mammal genes complement each other to make a whole.

    After doing some research I found that it has been proven that for an organism to be parthenogenesis it doesn’t necessarily have to have diploid cells. The link below provides a complete explanation for it.

    http://www.ansci.wisc.edu/jjp1/ansci_repro/misc/project_websites_08/tues/Komodo%20Dragons/what.htm

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  23. I had no idea that an animal could form an offspring with absolutely no input from a male parent. I just learned that parthenogenesis is a type of asexual reproduction in which a female gamete develops into an individual without fertilization. Most organisms that reproduce by parthenogenesis also reproduce sexually. This type of parthenogenesis is known as facultative parthenogenesis and organisms including water fleas, crayfish, snakes, sharks, and Komodo dragons reproduce in this manner. In apomictic parthenogenesis the mother of the offspring duplicates the female sex cell by mitosis producing two diploid cells in order to have the chromosomes needed to develop into an embryo. Parthenogenesis could not occur in high order vertebrates such as mammals because the offspring would have double the amount of maternal genes and would not develop properly in order to be fully functional or survive. Link to the information about parthenogenesis: http://biology.about.com/od/geneticsglossary/g/parthenogenesis.htm

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    • “The genre of feminist science fiction has explored single-sex reproduction in depth, particularly parthenogenesis, as well as gendered control over the ability and right to reproduce.” — Via

      Here’s a cover of one science fiction novel by Margaret Atwood that uses parthenogenesis:

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  24. Nature has a way to make everything work out and leave offsprings to continue their race. This information on how some mother animals can have children without a father is truely mindblowing because all our lives we have been tought that a mother and a father can create a baby but never that one alone could. Do to this post I searched for animals that can reproduce alone and also found some animals that change genders in order for reproduction to take place. One example of these animals is the Garter Snakes and like them many more. The admiration on the ways nature makes reproduction happen one way or another is without word and like that other incredible processes ocurred in nature.http://voices.nationalgeographic.com/2013/09/22/7-gender-bending-animals/

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  25. It’s absolutely astounding that some eukaryotic, complex organisms are able to reproduce asexually. It’s especially surprising that big animals such as the komodo dragon or different types of sharks do this regularly! When one thinks of asexual reproduction the thing that first comes to mind are prokaryotes or very simple organisms. Now, with these pieces of information, scientists can prove that point of view wrong. Furthermore, scientists have argued that the mother is still considered a diploid in vertebrates because “haploid eggs are useless”. Even though the process only occurs in .1% of vertebrates and cannot happen in mammals because they cannot perform automixis since each egg cell needs chromosomes from a sperm cell, it should be given more importance in the biological community. This weird phenomenon in nature should be given more publicity and should be discussed in class, especially when talking about genetics, asexual reproduction, or meiosis.

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  26. References:
    -http://bioteaching.com/parthenogenesis/
    -http://www.findingdulcinea.com/features/science/environment/Parthenogenesis–When-Animals-Reproduce-Without-a-Mate.html

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  27. Until this point I had no idea that females could reproduce without absolutely no help of the male. I searched for the definition of parthenogenesis and found out that it is a type of asexual reproduction in which the offspring develops from unfertilized eggs. This process of reproduction cannot happen in mammals since this would mean that the offspring will inherited double the amount of the mother’s genetic material and lack the paternal one thus leading to future possible defects in the offspring. Although this an absolutely strange method of reproduction I think it would be a very interesting topic to discuss in class.https://en.wikipedia.org/wiki/Parthenogenesis

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  28. Parthenogenesis means “virgin birth”. It occurs frequently but we are not familiarized with the term. It is a type of asexual reproduction that does not require fertilization of an egg, although some may argue it is more likely to be an incomplete sexual reproduction. Relating this topic with evolution which is the most discussed theme in our biology course, I found it to be amazing because a single female can start and sustain a new population. This is a video of a shark that reproduced without a mate and it also touches the possibility of humans doing the same.

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