Reptile & Amphibian Forums

Just plain crazy, who wants to try this with their snake clutches to see if they can change the sex ratios?

I might give it a try next year!

The link:
http://www.cell.com/current-biology/abstract/S0960-9822(09)01128-2

The papers abstract:
Current paradigms may substantially underestimate the complexity of reptilian sex determination. In previous work, we have shown that the sex of a hatchling lizard (Bassiana duperreyi, Scincidae) does not depend entirely on its genes (XX versus XY sex chromosomes); instead, low nest temperatures can override genotype to produce XX as well as XY males. Our experimental studies now add a third mechanism to this list: sex determination via yolk allocation to the egg. Within each clutch, the eggs that produce daughters are larger than those that produce sons. If (and only if) eggs are incubated at low temperatures, removing yolk from a newly laid egg turns the offspring into a male. Adding yolk from a larger (but not smaller) egg turns the recipient egg's offspring into a female. Remarkably, then, offspring sex in this species is the end result of an interaction between three mechanisms: sex chromosomes, nest temperatures, and yolk allocation.

If that aint some of the craziest S^&% I ever heard
Vinny
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“There is a grandeur in this view of life, with its several powers, having been originally breathed into a few forms or into one; and that whilst this planet has gone on cycling according to the fixed laws of gravity, from so simple a beginning endless forms most beautiful and most wonderful have been, and are being, evolved.” -C. Darwin, 1859

Natural Selection Reptiles

Where's my utility knife, I'm gonna do some yolk allocation!

Think I'll stick to chance for sex ratios, just easier, lol! Very interesting though.
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Mark

By adding yolk from "big eggs"(females), small eggs become female. How is this not genetic?? If you were to add yolk from another small egg(male) to make a female THAT would be news. I can see guys here sacrificing males all over the place,lol.

Its not genetic because yolk has no cells (no cells, no genome, therefore no genes), just a mass of fats, other lipids, calcium and, most importantly, hormones. All deposited by the mother. So, it looks the maternal deposited hormones (or some other "factor" can override the sex determination of the embryo. Its no so weird since various things can screw up sex determination. The real question is if the feminized males are fertile

Vinny
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“There is a grandeur in this view of life, with its several powers, having been originally breathed into a few forms or into one; and that whilst this planet has gone on cycling according to the fixed laws of gravity, from so simple a beginning endless forms most beautiful and most wonderful have been, and are being, evolved.” -C. Darwin, 1859

Natural Selection Reptiles

If "yolk is yolk" and has no cells, then why doesnt adding yolk from smaller eggs help make the change? Makes no sense.

I obviously didnt do the experiment so can only give an informed guess, but my guess is that females can ID which embryos are female and then give them some extra goodies in the yolk, likely hormones and some extra yolk. The extra yolk makes them bigger. As for the evolutionary origin of this i have no idea

Vinny
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“There is a grandeur in this view of life, with its several powers, having been originally breathed into a few forms or into one; and that whilst this planet has gone on cycling according to the fixed laws of gravity, from so simple a beginning endless forms most beautiful and most wonderful have been, and are being, evolved.” -C. Darwin, 1859

Natural Selection Reptiles

Vinny, that is insane man. I'll let you give it a try and let us know how it goes! LOL

Dave
DNS Reptiles

Ah c'mon. Those Cosala eggs you get are pretty big, why not send some over. I'll treat them well I promise
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“There is a grandeur in this view of life, with its several powers, having been originally breathed into a few forms or into one; and that whilst this planet has gone on cycling according to the fixed laws of gravity, from so simple a beginning endless forms most beautiful and most wonderful have been, and are being, evolved.” -C. Darwin, 1859

Natural Selection Reptiles

it's an interesting observation.

on the one hand, in any group of eggs half will fall into a "larger" (by weight, presumably) category and half into a "smaller" category, thus matching the 50-50 gender division you'd expect from random genetic selection.

However, we've all had clutches with most or all the hatchlings of the same gender. Were the clutches that produced a majority of male offspring comprised of smaller eggs than those in other clutches that produced mostly females? For those of us who are obsessive record-keepers, it might be appropriate in the future to weigh clutches and record average egg weight along with genders. Over time, it's possible a trend might emerge that we simply hadn't seen before.

Plus there's the more obvious point of this research: Might the gender distribution have been equalized with re-distribution of yolk?