Sex determination based on food availability

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Discussion Overview

The discussion revolves around the relationship between food availability and sex determination in various animal species. Participants explore how environmental factors, such as resource scarcity and predator presence, may influence sex ratios and reproductive strategies. The conversation includes examples from specific species and raises questions about the underlying biological mechanisms.

Discussion Character

  • Exploratory
  • Debate/contested
  • Conceptual clarification

Main Points Raised

  • Some participants inquire about animals where sex determination is influenced by food availability, citing examples like the Common reed frog and the Desert Greenland Whiptail lizard.
  • There is a mention of a claim that, in certain animals, mothers give birth to fewer males during times of resource scarcity, suggesting a biological mechanism that adjusts sex ratios based on environmental conditions.
  • Questions are raised about how the presence of predators might affect sex determination and internal biological processes in various species.
  • One participant references Trivers' work and its connection to Dawkins, indicating a broader theoretical context for the discussion.
  • Another participant introduces the idea that in turtles, sex determination is influenced by egg temperature rather than external factors like diet.
  • Some participants express skepticism about whether sex determination is influenced by external factors, suggesting it may be genetic instead.

Areas of Agreement / Disagreement

The discussion features multiple competing views regarding the influence of external environmental factors on sex determination. There is no consensus on whether these factors play a significant role or if genetic factors are more determinative.

Contextual Notes

Participants express uncertainty about the mechanisms behind sex determination and the extent to which environmental factors influence biological outcomes. The discussion includes references to specific studies and examples, but these are not universally accepted as conclusive.

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[Mentor Note -- Merged accidental double-thread-start]

In which animals is sex determination based on either food availability.

Females of the Common reed frog have shown to exhibit a sex change, which is thought to occur due to low male density in the environment, so that's not quite what I mean.

other animals, when resources are scarce, mothers give birth to fewer males than normal.

Then there's the Desert Greenland Whiptail lizard, who displays parthenogenesis, but when does it do that? How does the environment affect internal biology, such as the presence of predators?
 
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In which animals is sex determination based on food availability?
And as a side question: In which animals is sex determination based on the presence of predators?

Let me elaborate on both questions.
Females of the common reed frog have shown to exhibit a sex change, which is thought to occur due to low male density in the environment, so that's not quite what I mean.
Then there's the Desert Greenland Whiptail lizard, who displays parthenogenesis. But why/how/when does it do that? How does the environment affect internal biology, such as the presence of predators? Does such presence affect anything to any animal?

In this movie, it says that: "In certain animals, when resources are scarce, mothers give birth to fewer males than normal. Somehow, female biology suppresses boy survival in the womb during tough times, and boost it when times are good.".
Why would that be so? What does food availability have to do with sex determination?

So yes, I'm asking 2 question, but taken together, I'm actually after 1 question: what does sex determination have to do with any threat external to the womb?
 
mark! said:
In which animals is sex determination based on food availability?
And as a side question: In which animals is sex determination based on the presence of predators?

Let me elaborate on both questions.
Females of the common reed frog have shown to exhibit a sex change, which is thought to occur due to low male density in the environment, so that's not quite what I mean.
Then there's the Desert Greenland Whiptail lizard, who displays parthenogenesis. But why/how/when does it do that? How does the environment affect internal biology, such as the presence of predators? Does such presence affect anything to any animal?

In this movie, it says that: "In certain animals, when resources are scarce, mothers give birth to fewer males than normal. Somehow, female biology suppresses boy survival in the womb during tough times, and boost it when times are good.".
Why would that be so? What does food availability have to do with sex determination?

So yes, I'm asking 2 question, but taken together, I'm actually after 1 question: what does sex determination have to do with any threat external to the womb?

This is interesting. Trivers work features in Dawkins books.

Diet.

https://academic.oup.com/biolreprod/article/71/4/1063/2666975

I would look at Turtles too not diet, egg Temperature determines sex.

These creatures are fascinating, I don't think you can mention sex and organisms without mentioning these.
One Jim has mentioned.

https://en.m.wikipedia.org/wiki/Rotifer
 
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pinball1970 said:
Diet.
Sex determination NOT due to external/environmental factors, then?
 
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mark! said:
Sex determination NOT due to external/environmental factors, then?
If it is not external then it is genetic
 

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