> In big cats a tigon, a lion-tiger cross, is bigger than either
I don't think this is right. The hybrid with a lion father and tiger mother is the huge one, but the father comes first in the name of the hybrid; tigons (male tiger / female lion) aren't so large.
The reason for the difference is that male lions brand their offspring's DNA with the urge to grow large, while female lions counter with the opposite urge. For a lion/lion pairing, this balances out, but tigers don't have the same war between the sexes going on, and the maternal tiger genetic contribution is defenseless against the paternal lion one.
Humans, by the way, do something similar: the same genetic defect causes "Prader-Willi syndrome" if it came from the father, and "Angelman syndrome" if it came from the mother.
I don't think this is right. The hybrid with a lion father and tiger mother is the huge one, but the father comes first in the name of the hybrid; tigons (male tiger / female lion) aren't so large.
The reason for the difference is that male lions brand their offspring's DNA with the urge to grow large, while female lions counter with the opposite urge. For a lion/lion pairing, this balances out, but tigers don't have the same war between the sexes going on, and the maternal tiger genetic contribution is defenseless against the paternal lion one.
Humans, by the way, do something similar: the same genetic defect causes "Prader-Willi syndrome" if it came from the father, and "Angelman syndrome" if it came from the mother.