Paper 2 Discussion Questions

Please comment with a 2-3 sentence response to each pf the questions below:

Question 1: It seems from the article that S. ocellatus males don’t transform into a different morph once they’ve “reached” the nesting morph. Do you think that if we manipulated a nesting male’s hormone levels (for example increase the cortisol and decrease the 11-kt), they would transform into a satelite/sneaker, which are better suited for these hormone levels, or still remain in the seemingly solid nesting morph?

Question 2: In this paper, they described the hormonal pattern of different alternative reproduction tactics from transcriptomic level to behaviour in Symphodus oscellatus. There are still no information about what causes the transitions between the reproductive morphs. Based on this study, how would you start to investigate the hormonal background of the transition to nesting male? (What would be your general methods and/or which hormone and/or which receptor etc. would you start your investigation with?)

9 thoughts on “Paper 2 Discussion Questions

  1. Q2 (second try): I would observe fish and measure hormone levels over time / while directly manipulating levels of cortisol and 11-kt (better to do both – in case of manipulating 11kt and cortisol we’d need to have a control group), because only measuring hormone levels of different fish will not be able to answer how and why the transition happens.

  2. Q1: I think that with manipulating the hormone levels we could turn a nesting male into sneaker/satellite at least in behavior. I also think the colorization would change as it’s very strongly linked to hormonal activity in fish.
    Although the differences in hormone levels between nesting and satellite males were not significant, it was described previously and also very visible here (so I would say more research on these differences is necessary)

  3. I. I think if we manipulate with hormone levels, as some of the authors did in their studies, we must be sure to manipulate on specific regions to understand the mechanism of the actions.


  4. 2. I would get some males that are as jung as possible. I would keep them in groups and also separated (one male and one female). I would have one control one treated with 11 kt and 1 with cortisol. Check them for ostrogen glucocorticoid and mineralocorticoid receptors.

  5. 1. I think that there is a possibility they would transform, as 11kt is associated with certain behaviours . So maybe nesting males and satelites could transform to sneakers. But We have to take into account that there are other environmental factors and also there can be other hormonal factors as well. Also the already learned behavioural patterns might not change instantly.

  6. 1. The behavioral morphs are not only determined by hormones, but also have differences in hormone receptors. The paper suggests that they change from one morph to another with development, but there is plasticity in this timing of the changes in life history. If this is the case, I do not think that changing hormone levels should be able to reverse changes in life history.

    2. I would start by increasing the 11-kt levels in sneaker males to see whether this alone would initiate the transition to nesting males. I would do this because I think it would be less complicated than trying decrease cortisol levels or change the hormone receptors. I would start with the simplest experiment, and use the results from this to make decisions on future studies.

    • we are not saying that we are going to change life history, the idea that we can make nesting male be like stellite male by affecting hormones which is very feasible, for example 11-kt levels which is higher in nesting male comparing with satellite male and that have been associated with paternal care and enhanced aggression which the nesting male showed, imagine if we blocked this hormone this behaviors are going to reduce or stopped which is logical cuz we stopped the source of the patterns and beside that increase the cortisol level will make us transform the nesting male to satellite male especially that nesting male have high abundance of Glucocorticoid receptors (GR).

      • 2. commenting your second Reply:
        I am partial agree with you in your experiment, first of all increasing 11-kt is important for sneaker male in order to get paternal care and enhanced aggression patterns but according to the article nesting male have the highest 11-kt level and lower cortisol comparing with the sneaker, thus if you want to initiate the transition is better to control all the parameters because I think the transition will not happen because we are going to have like antagonist between the cortisol effect and 11-kt effect.

  7. Reply for the first question:
    I believe that we can make nesting male transform into satellite by manipulating hormone levels, according to the article Glucorticoid receptor (GR) expressed at higher levels in satellites and nesting males which means that if we decrease the 11-ketotestosterone and increase cortisol level, the hormone will bind to the receptor then moves across the nuclear membrane into the nucleus of the cell, where it binds to specific DNA sequences, regulating the expression of certain genes, and thereby increasing the levels of the proteins encoded by these genes so with that we can transform nesting to satellite male but is not the case for sneaker male because cortisol receptors expressed in small abundance.

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