This paper is a few years old, but I only heard about it in this morning's class on sexual conflict. It kinda turned my worldview upside down. Allow me to geek out about it a bit
Pischedda A, Chippindale AK (2006) Intralocus Sexual Conflict Diminishes the Benefits of Sexual Selection. PLoS Biol 4(11):e356
Basically, although one would expect that there is a point to sexual selection by mate choice, that may not always be true. Many theories of sexual selection focus on "good genes" in some way. However, in the fruit flies used in this experiment, a match between a very fit male and a very fit female produced the least fit offspring. The best males had the crappiest daughters and the best females had the crappiest sons. Moreover, a father's fitness had no effect whatsoever on the quality of his sons, although a mother's fitness correlated positively with that of her daughters.
This is because of genes that have opposite fitness effects on males and females. That's why mating with a good male guarantees you poor quality daughters: what made their father successful is likely to have the opposite effect on them. Such genes (at least in fruit flies) are concentrated quite heavily on the X chromosome (fruit flies have a similar XY sex determination system to ours, and their X chromosome is quite large), which explains why sons don't inherit their father's fitness (they don't inherit his X chromosome).
The really puzzling thing about this is that female fruit flies are choosy, and males court them quite passionately to get them to mate. Yet choosing the best males is actually counterproductive from females' point of view. Why on earth do they still do it? Do males just manipulate them so cleverly that they don't know what's good for them? Or is it a particularly pointless example of Fisher's runaway process?
There is a hypothesis that females prefer attractive males because they will father attractive sons (who will then give them lots of grandchildren), but that doesn't appear to be the case here.
Another point I found quite interesting is that similar considerations might explain why pronounced sexual dimorphism, with gaudy and extravagant males, is so common in birds and butterflies: in these groups, it's the males who have two X (or, technically, Z) chromosomes, so their sons DO inherit all that fancy stuff.
Anyway, I thought this study was quite cool. It definitely challenged my long-held ideas about sexual selection.
</evolutionary biologist geeking out>
Pischedda A, Chippindale AK (2006) Intralocus Sexual Conflict Diminishes the Benefits of Sexual Selection. PLoS Biol 4(11):e356
Basically, although one would expect that there is a point to sexual selection by mate choice, that may not always be true. Many theories of sexual selection focus on "good genes" in some way. However, in the fruit flies used in this experiment, a match between a very fit male and a very fit female produced the least fit offspring. The best males had the crappiest daughters and the best females had the crappiest sons. Moreover, a father's fitness had no effect whatsoever on the quality of his sons, although a mother's fitness correlated positively with that of her daughters.
This is because of genes that have opposite fitness effects on males and females. That's why mating with a good male guarantees you poor quality daughters: what made their father successful is likely to have the opposite effect on them. Such genes (at least in fruit flies) are concentrated quite heavily on the X chromosome (fruit flies have a similar XY sex determination system to ours, and their X chromosome is quite large), which explains why sons don't inherit their father's fitness (they don't inherit his X chromosome).
The really puzzling thing about this is that female fruit flies are choosy, and males court them quite passionately to get them to mate. Yet choosing the best males is actually counterproductive from females' point of view. Why on earth do they still do it? Do males just manipulate them so cleverly that they don't know what's good for them? Or is it a particularly pointless example of Fisher's runaway process?
There is a hypothesis that females prefer attractive males because they will father attractive sons (who will then give them lots of grandchildren), but that doesn't appear to be the case here.
Another point I found quite interesting is that similar considerations might explain why pronounced sexual dimorphism, with gaudy and extravagant males, is so common in birds and butterflies: in these groups, it's the males who have two X (or, technically, Z) chromosomes, so their sons DO inherit all that fancy stuff.
Anyway, I thought this study was quite cool. It definitely challenged my long-held ideas about sexual selection.
</evolutionary biologist geeking out>