Yes! For the individual, it does not make sense to adjust the sex ratio with changes in climate, but for the species overall it’s not that bad or even positive. Sex chromosomes do a much better job for the individual here (And would be selected for if temperature changes were happening too often). I do think I had confused thinking at the time, because I also had just read about a theory in humans that high status females supposedly produce more males (so payoff could be different between low and high status, but that doesn’t apply in this case, and it’s not born out well empirically anyway).
What I do think is true: It might not be that much of a coincidence that climate change would lead to more females. If it was the other way around, there is a higher likelihood the species would have gone extinct from a meteor, and we wouldn’t observe it today. Having 1% females and 99% males is going to lead to a really bad population bottleneck, but having 1% males and 99% females just means the remaining males have little competition (the effective population is still reduced to some extent). The fact that turtles don’t fit this pattern and look like they should have gone extinct with the last meteor tells you how weak and slow selection between species is.
I was thinking of this when I saw these articles complaining how sex ratios are supposedly endangering sea turtles. It doesn’t seem obvious to me that the sex ratios alone should be a problem (although 1⁄99 is probably bad).
Yes! For the individual, it does not make sense to adjust the sex ratio with changes in climate, but for the species overall it’s not that bad or even positive. Sex chromosomes do a much better job for the individual here (And would be selected for if temperature changes were happening too often). I do think I had confused thinking at the time, because I also had just read about a theory in humans that high status females supposedly produce more males (so payoff could be different between low and high status, but that doesn’t apply in this case, and it’s not born out well empirically anyway).
What I do think is true: It might not be that much of a coincidence that climate change would lead to more females. If it was the other way around, there is a higher likelihood the species would have gone extinct from a meteor, and we wouldn’t observe it today. Having 1% females and 99% males is going to lead to a really bad population bottleneck, but having 1% males and 99% females just means the remaining males have little competition (the effective population is still reduced to some extent). The fact that turtles don’t fit this pattern and look like they should have gone extinct with the last meteor tells you how weak and slow selection between species is.
I was thinking of this when I saw these articles complaining how sex ratios are supposedly endangering sea turtles. It doesn’t seem obvious to me that the sex ratios alone should be a problem (although 1⁄99 is probably bad).