why are Ligers bigger than Lions and Tigers?

[gustavolacerda]

from Wikipedia: Liger
It is believed that this is because female lions transmit a growth-inhibiting gene to their descendants to balance the growth-promoting gene transmitted by male lions. (This gene is due to competitive mating strategies in lions.) A male lion needs to be large to successfully defend the pride from other roaming male lions and

Comments

[altamira16]

I think his explanation was confusing as well. I have no references, but I am going to give you an explanation that is slightly different that I like better

[gustavolacerda]

Oh, yeah. This seems plausible at first sight. It would be interesting to look at the actual Sexual Dimorphism Indices for both Lions and Tigers.

But what about male Ligers? Are they then huge for the same reason as the female Ligers, namely because they miss the "smallening" Lion X?

If this is correct, it's interesting how work the Lions' genes work against each other: it seems unnecessary to have both a "biggening" Y a "smallening" X, since any one of them should be enough.

Against this theory, though, seems to be the observation that Tigons are not significantly smaller than their parents. (or am I wrong?)

[altamira16]

If Tigons are not significantly smaller than their parents, it could be that the tempering effect of the female lion works on some "biggening" in Y that is specific to the male lion but missing in the male tiger.

[darius]

That Wikipedia passage sounds kind of garbled, but that kind of conflict is common. It's not the case that the mother and father's reproductive interests are identical.

[gustavolacerda]

It's not the case that the mother and father's reproductive interests are identical.

Can you make this more precise?

AFAICT, the only difference are the future opportunity costs, which tend to be much greater for the mother (because she sacrifices future breeding opportunities). The success of a child affects both parents' Darwinian scores equally.

[darius]

Right -- if the benefits are the same but the costs are not, the net benefits are different. There's still the question of how a gene could know if it's inherited from the mother or the father; there are at least two ways: sex-linked genes and imprinting. I've read in a few places about imprinting leading to conflicts between human fetuses and their mothers, though I'm not sure how firmly established that is yet.

[iole200]

I think the discussion of cost to the lion pride is confusing the issue

[gustavolacerda]

All evolutionary fitness in measured in ONE WAY: how many times does an individual manage to produce offspring that are going to produce offspring as well:

Exactly. What I call "Darwinian score" is exactly this recursive notion.

This is a big investment and a female has a limited supply

Do females ever run out of eggs?

This mystery is where male bravado and showy manes come from... If you can maintain a big stupid tuft of mane then maybe your genes are OK.

Right. This "handicap" idea and sexual selection in general seems to make our world a lot more interesting: deer antlers, peacock tails, music, etc. High testosterone levels are also a handicap, since it weakens the immune system.

A female doesn't want to invest too much in this offspring, to save her strength and have more later she silences genes that tend to make the offspring gigantic.Are you suggesting that a mother can choose in which kids to silence those genes

[anonymous]

wow!!!!!!!!!!!! you have intristing facts

[anonymous]

bad english earnest williams

[gustavolacerda]

is this your name?