DPBioY2 - 2020 - 10.3 Gene Pool and Speciation
DPBioY2 - 2020 - 10.3 Gene Pool and Speciation
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DPBioY2 - 2020 - 9.3 Plant Growth
DPBioY2 - 9.3 Plant Growth 2 marks for your questions 3 marks for your reply 2 marks for submitting by July 16th, 2020
1. How realistic is it to achieve genetic equilibrium in a species?
ReplyDelete2. How do changing environmental niches impact the speed of evolution?
3. How long, on average, would it take for reproductive isolation to result in speciation?
4. Does the theory of gradualism or the theory of punctuated equilibrium contain more (compelling) evidence to support it? What are some arguments for either side?
5. How do the existence of polyploid organisms impact how evolution occurs?
In regards to your 2nd question,
DeleteI was looking at an article that discussed the effect of climate change on the rate of evolution, one of the point that they made was that the rising temperatures can affect the way selection acts on a trait and its gene expression. If the environment leads to a strengthened selections or increases genetic variance, then the rate of evolution should also be increased as a result.
https://journals.plos.org/plosbiology/article?id=10.1371/journal.pbio.1001015#:~:text=Environmental%20conditions%20such%20as%20rising,of%20evolution%20should%20be%20accelerated.
To answer your fifth question, First, the process of polyploidization can itself generate species that are reproductively isolated from their diploid progenitors, increasing the number of species as a by-product of polyploidization but without a subsequent effect on diversification rates. Polyploidization is considered to be the main drive of plant species diversification and plays an important role in plant genome evolution. Basically, Polyploidization results in multi-copy genes that exist as paralogs to each other.
Deletehttps://www.sciencedirect.com/science/article/pii/S2468014119301980
https://www.sciencedirect.com/science/article/pii/S0092867407013402#:~:text=First%2C%20the%20process%20of%20polyploidization,subsequent%20effect%20on%20diversification%20rates.
To answer your 1st question,
Delete"In 1908 G. Hardy and W. Weinberg independently proposed that the frequency of alleles and genotypes in a population will remain constant from generation to generation if the population is stable and in genetic equilibrium. Five conditions are required in order for a population to remain at Hardy-Weinberg equilibrium:
A large breeding population
Random mating
No change in allelic frequency due to mutation
No immigration or emigration
No natural selection"
http://www.phschool.com/science/biology_place/labbench/lab8/concepts.html
General research has shown from a range of species that speciation takes about a million years.
Delete1. Would temporal reproductive isolation be a product of genetic mutation itself or selective pressures?
ReplyDelete2. Why does punctuated equilibrium and evolution occur? Does the environment cause a sudden change in pace of selective pressure and evolution?
3. What are the main causes of sympatric speciation?
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DeleteIn regards to your second question, it is thought that punctuated equilibrium occurs due to a change in selective pressures that quickly modifies the gene pool of a species.
DeleteFor your 3rd question, sympatric speciation is when the same species will differentiate without geographical isolation and pressures. A cause of this could be based on food source or a characteristic that spontaneously develops. When looking at the bird simulation that we did in class, this could happen through mutations.
Deletehttps://www.nationalgeographic.org/encyclopedia/speciation/#:~:text=Sympatric%20speciation%20occurs%20when%20there,characteristic%2C%20seems%20to%20develop%20spontaneously.
For your first question, I believe it is a mutation. "The mutation will change the DNA sequence of the two populations enough that the salamander populations can no longer successfully breed between each other making the populations of salamander become classified as different species". https://en.wikipedia.org/wiki/Reproductive_isolation#:~:text=Temporal%20or%20habitat%20isolation,-The%20Central%20Valley&text=The%20mutation%20will%20change%20the,become%20classified%20as%20different%20species.
Delete1. Would temporal reproductive isolation be a product of genetic mutation itself or selective pressures?
ReplyDelete2. Why does punctuated equilibrium and evolution occur? Does the environment cause a sudden change in pace of selective pressure and evolution?
3. What are the main causes of sympatric speciation?
To answer your third question, Sympatric speciation occurs when populations of a species that share the same habitat become reproductively isolated from each other. Scientists think that geographic isolation is a common way for the process of speciation to begin: rivers change course, mountains rise, continents drift, organisms migrate, and what was once a continuous population is divided into two or more smaller populations.
DeleteTo answer your first question,
DeleteI think it could be a result of both. In a source I found it said that it can happen through "mutation-ordered speciation" and that the organisms who have these genetic mutation could have the same selective pressures.
Here is the source I used: https://www.sciencedirect.com/topics/biochemistry-genetics-and-molecular-biology/reproductive-isolation
Who came up with the biological species concept and why was it accepted?
ReplyDeleteIs there any species that shows no evidence that it evolved?
What is an example of a random event affecting allele frequency?
To answer your first question, The development of what became known as the biological species concept began with a paper by Theodosius Dobzhansky in 1935, and was amplified by a mutualistic interaction between Dobzhansky, Alfred Emerson and Ernst Mayr after the second world war. I couldnt find anything however about why it was accepted.
DeleteTo answer your 2nd question,
DeleteCrocodylians are believed to have not gone through evolutionary processes.
https://www.smithsonianmag.com/science-nature/the-top-10-greatest-survivors-of-evolution-118143319/
To answer your third question, a random event that can affect allele frequency I found is called, "genetic drifting" and it is where alleles are just lost from the gene pool and it is does not have to do with selection.
DeleteHere is the source I used:
https://www.slideshare.net/tammi-1990/factors-affecting-allele-frequencies#:~:text=Genetic%20Drift%EF%82%9A%20Is%20the%20change%20in%20allele%20frequency,likely%20to%20have%20an%20effect%20in%20small%20populations.
1. What is an example of genetic equilibrium seen in the world? What is an example of populations that don't have genetic equilibrium?
ReplyDelete2. Is there speciation between humans?
3. Which one is correct: gradualism or punctuated equilibrium?
To answer your second question between humans as a whole I don't think there is speciation since we are still the same specie. However, there is genetic evidence supporting the argument of complex speciation between humans and chimpanzees. The study that I looked at suggests that human–chimpanzee speciation occurred less than 6.3 million years ago.
Deletehttps://www.nature.com/articles/nature04789#:~:text=Abstract,timing%20and%20process%20of%20speciation.&text=Human%E2%80%93chimpanzee%20genetic%20divergence%20varies,more%20than%204%20million%20years.
For your third question,
DeleteNeither theory is technically correct. It is still a big controversy between scientists and they are trying to find other forms of evidence that doesn't rely on the fossil record in order to better prove which theory is most likely correct.
https://www.thoughtco.com/gradualism-vs-punctuated-equilibrium-1224811
For the first question,
DeleteAn example of this in humans would be a heterozygote for brown eye color. The person would carry both a dominant brown allele “B” and a recessive blue allele “b” yet have brown eyes. I personally cant find a population that doesnt have genetic equilibrium.
1) What are the stages of speciation? and What are some examples of sympatric speciation?
ReplyDelete2) Are humans polyploidy?
3) What is the phylogenetic species concept?
To answer your second question, no humans are not polypoidy. However, recent studies show that humans might have had polypoidy ancestors.
Deletehttps://www.nature.com/scitable/topicpage/polyploidy-1552814/
To answer your 2nd question,
DeleteHumans are not, on average, polyploidy. "Polyploidy occurs in humans in the form of triploidy (69,XXX) and tetraploidy (92,XXXX). Triploidy occurs in about two to three percent of all human pregnancies and around 15 percent of miscarriages. The vast majority of triploid conceptions end as miscarriage and those that do survive to term typically die shortly after birth. In some cases, survival past birth may occur longer if there is mixoploidy, with both a diploid and a triploid cell population present. Triploidy may be the result of either diandry (the extra haploid set is from the father) or digyny (the extra haploid set is from the mother). Diandry is almost always caused by the fertilization of an egg by two sperm (dispermy). Digyny is most commonly caused by either failure of one meiotic division during oogenesis leading to a diploid oocyte or failure to extrude one polar body from the oocyte.
Diandry appears to predominate among early miscarriages, while digyny predominates among triploidy that survives into the fetal period. However, among early miscarriages, digyny is also more common in those cases under 8.5 weeks gestational age or those in which an embryo is present."
https://www.newworldencyclopedia.org/entry/Polyploidy#Polyploidy_in_humans
For your third question,
DeleteEncyclopedia.com defines the phlyogenetic species concept as "a species as an irreducible group whose members are descended from a common ancestor and who all possess a combination of certain defining, or derived, traits". The main focus here is that their evolutionary history is "shared" and that there is no problem of different species were to breed.
https://www.encyclopedia.com/plants-and-animals/zoology-and-veterinary-medicine/zoology-general/phylogenetic-species-concept#:~:text=phylogenetic%20species%20concept%20(PSC)%20The,%2C%20traits%20(see%20apomorphy).
For the first question,
DeleteThere are three stages of speciation. Isolation of populations.
Divergence in traits of separated populations and Reproductive isolation of populations that maintains isolation when populations come into contact again.
An example of Speciation is in Midas cichlid fish. One species lives in lake Apoyo and the other lives in a volcanic crater lake in Nicaragua.
https://biologydictionary.net/sympatric-speciation/
1. What is a more detailed explanation of directional selection? How is it different from the other two types?
ReplyDelete2. What are some examples of organisms that were affected by punctuated equilibrium?
3. Which of the two theories regarding the pace of evolution (gradualism and punctuated equilibrium) holds more compelling evidence?
For your third question,
DeleteInterestingly enough neither theory holds more evidence as they both depend on the fossil record and how its missing gaps are interpreted by different scientists.
https://www.thoughtco.com/gradualism-vs-punctuated-equilibrium-1224811
To answer the first question.
DeleteThe directional selection theory says that an extreme phenotype is favored over other phenotypes and this causes the allele frequency (how often the variant of a gene shows up in a population) to shift over time in favor of the extreme phenotype. Stabilizing selection means a non-extreme trait is favored instead of one of the two extreme traits. while Disruptive selection favors both extreme traits in a population.
For your second question, punctuated equilibrium is a theory that evolution happens in spurts of time periodically in response to environmental changes. An example would be this: "A species of sea animals lives, breeds, and dies for thousands of years. Suddenly, the sea level changes and the animals must adapt. Their bodies develop in order to accommodate the environmental change, and from then on are evolutionarily different from their ancestors." This source has more examples:)
Deletehttps://examples.yourdictionary.com/punctuated-equilibrium-examples.html
1. What are some examples of polyploidy animals?
ReplyDelete2. Could their be speciation within humans?
3. What are the differences and similarities of Directional Selection, Stabilizing Selection and Disruptive Selection?
To answer your second question, scientist have said there has been speciation between homo sapiens in the past. When they thought that we evolved from monkeys but there are still monkeys.
DeleteHere is the source I used: http://rafonda.com/interbreeding_between_species.html#:~:text=Some%20genetic%20data%20from%20humans%2C%20chimps%2C%20and%20orangutans,with%20their%20ancestors%2C%20but%20not%20many%20nor%20recently.
I am not sure If I am completely correct so if anybody has anything to add please do.
In regards to your first question, polyploidy is found in some fish, insects, some reptiles, and some amphibians.
DeleteThe differences between the types of natural selection:
Deletein directional selection, only one extreme trait is favored over the other extreme trait.
in disruptive selection, both extreme traits are favored over the intermediate trait.
in stabilizing selection, the average traits are favored over the extreme traits.
The similar types of natural selection are disruptive and directional because the extreme traits are favored over intermediate traits
1. What is an example of a species that follows the Hardy-Weinberg equilibrium?
ReplyDelete2. Can someone explain gradualism?
3. Can someone explain punctuated equilibrium?
For your third question,
DeletePunctuated equilibrium is the theory which fills in the gaps of the gradualist theory. Punctuated equilibrium theorizes that evolution occurs overtime, but in short fragments with dramatic change. This could be due to changes in environment, sudden population isolation, etc. This is followed by long static periods of no evolutionary change.
For your second question,
DeleteGradualism is the slow and progressive evolutionary change in a species overtime. Gradualism is the idea that changes in an organism do not happen spontaneously, but rather selective pressures slowly leads to change. However, there are some issues with this theory since intermediate fossil records have not been located for many notable species.
In regards to your first question, I could not find examples of this because it is a theoretical equilibrium. It does not really exist in nature but helps scientists conceptualize, theoretically, intermediate or extreme characteristics.
DeleteThis comment has been removed by the author.
ReplyDelete1. Is temporal isolation considered an evolutionary change?
ReplyDelete2. How can punctuated equilibrium exist without gradualism?
This comment has been removed by the author.
Delete1. Yes temporal isolation is an evolutionary change because the same species diverges into 2 species over time because they only have a population of their species to populate with (since they have different mating periods). So if once population experiences a selective pressure then they populate with the same population, resulting in a different species.
Delete1. Does the first population of natural selection happen by random mutation, then those randomly mutated organisms are favored in the environment?
ReplyDelete2. Does punctuated equilibrium change when their environment or food source availability changes?
3. Does punctuated equilibrium result in a smaller population of a species?