Forum – Questions

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39 thoughts on “Forum – Questions

  1. Dr. Hickerson,
    question # 29 0n the practice exam is confusing me a little. It seems like the appropriate answers are gamma diversity and extinction, but I cant find the data to back it up 100%.
    Thanks

    1. # 28 and 29 cover material we haven’t gotten to yet (and will therefore not be on the exam). In case you are curious, the answers are “meta-population” and extinction.
      mike

  2. I have a question about species evenness? Specifically about which population would be more diverse; a population containing the same amount species per hectare or a six different species of different proportions? I am thinking a species with the same amount of species in a hactare is the answer but I am not sure.

    1. Even if the two samples (1. same amount species per hectare or 2. six different species of different proportions) might both have the same species richness (6 species), the first sample will have a higher amount of evenness and hence have higher diversity.

      Shannon’s Index can show this exactly (formula is in the lecture)

      Sample 1 –
      Proportions of 6 species are all 1/6 (0.1666667)

      (0.1666667*ln(0.1666667))+(0.1666667*ln(0.1666667))+(0.1666667*ln(0.1666667))+(0.1666667*ln(0.1666667))+(0.1666667*ln(0.1666667))+(0.1666667*ln(0.1666667))
      H’ = -1.79176

      Sample 2 –
      Proportions of 6 species 0.8, 0.15, 0.1, 0.05, 0.07, 0.03

      (0.7*ln(0.8))+(0.15*ln(0.15))+(0.1*ln(0.1))+(0.05*ln(0.05))+(0.1*ln(0.07))+(0.05*ln(0.03))
      H’ = -1.262068

      -1.79176 < -1.262068, and so therefore sample 1 is more diverse than sample 2.

  3. I have a question about the slide number 40 from lecture 4

    What is the prediction after a
    cargo ship accidentally brings in
    43 populations from 43 species of
    arthropods and ?

    S = Sˆ + 43

    on the next slide, there is a green vertical line showing s^+ 43

    so the dynamic quilibrium shifted to a new position?

    i thought the dynamic equilibrium doesnt change

    thank you

  4. Good day Professor,

    For question 24, indirect interaction is a way plants protect themselves. However, is myrmecophily a form of indirect interaction or do they mean completely different thing?

    1. Question #22 is poorly worded and should have a “none of the above option”. At the June solstice, the latitude at the Tropic of Cancer will receive perpendicular sunlight. This occurs in places such as Mexico, the Sahara desert, and India. Florida comes close, but not quite.

      thank you for pointing this mistake out.

    2. Question #22 is poorly worded and should have a “none of the above option”. At the June solstice, the latitude at the Tropic of Cancer will receive perpendicular sunlight. This occurs in places such as Mexico, the Sahara desert, and India. Florida comes close, but not quite.

      thank you for pointing this mistake out.

    3. Question #22 is poorly worded and should have a “none of the above option”. At the June solstice, the latitude at the Tropic of Cancer will receive perpendicular sunlight. This occurs in places such as Mexico, the Sahara desert, and India. Florida comes close, but not quite.

      thank you for pointing this mistake out.

  5. I am not understanding this question on your review for the lecture, If a butterfly species flys from continental US to Hawaii, can it create a new population there? I am confused on how to answer it.

    1. The review question was “If a single butterfly flies from the US mainland to Hawaii,
can it start a new population of that species?”

      If the single butterfly individual was a gravid female (fertilized eggs), it i might be possible to form a new hawaiian population. However, this would certainly be a rare event.

  6. I’m a little confused about the last question, #49. If the species richness and diversity are equal, then the eveness of the different species must also be equal so how can the biodiversity be totally different? If the eveness was different, I could understand a difference in biodiversity. Under the given parameters, however, don’t they have to be pretty much identical communities?

      1. Can we answer this question in this way: even thou 2 communities have the same species diversity and richness, there could be different types of individual species in each community therefore it influences the biodiversity at a large scale.

        Hickerson: No, that is not sufficient. There are always different types of individual species in different communities. How different? You must refer specifically to PD in this case.

      2. Mistyt: Can we answer this question in this way: even thou 2 communities have the same species diversity and richness, there could be different types of individual species in each community therefore it influences the biodiversity at a large scale.

        Hickerson: No, that is not sufficient. There are always different types of individual species in different communities. How different? You must refer specifically to PD in this case.

    1. #15 the best answer would be D. They can not co-exist (Fig C from #14) if there is inter-specific competition.

      #42 – true

      #38 – false, there is no set age for species nor for families

  7. I also have a question on question 27 and 30. I was wondering if the graph for Q#27 is a J curve that fits the concept saying ” few common species and many rare species.”
    And for Q#30, the graph would be a direct relationship, as the island size gets bigger, the bird species richness also increase.

  8. Im having this confusion in regards to questions 46. I dont know how to differentiate between species diversity and species richness?

  9. Hey Professor,
    What should the answers be for questions 10 and 11? Also, should number 6 be rare, because pandas are geographically isolated? Another question should number 13 be Mordor, cause its near the mainland and its a big island? Thanks!!!

    1. #10 rarefaction
      #11 competition
      #6 secondary endemic, but really, the current distribution is disjunct as well as being a secondary endemic. Thank you for pointing this error out
      #13 Mordor

    1. thank you for pointing this out. Although you can calculate the missing survival rate (0.5) and survivorship (0.004), there is no way you can calculate fecundity from the information you are given. Instead, this must be measured or estimated from a population sample. However, one could use fecundity to estimate population growth over multiple generations.

  10. hello professor quick question on chapter 6, it say that ” biological evolution is change in heritable characteristics in populations over time” doesn’t that mean that there must have been a mutation within an individual’s gene that was favored by natural selection hence, this favored gene was passed on from generation to generation from that one individual? Since the slide also says that “individuals do not evolve” then what name would you give this phenomenon?

    1. Hi Ebony,
      good question. First, natural selection is just one force in evolution (for example, genetic drift and gene-flow are other forces). Second, in your example, the individual didn’t evolve but instead the allele frequencies changed in the population over time and hence the population evolved. That individual may have had a high fitness, but the individual did not evolve.
      mike

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