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Evolutionary biology has long emphasized that males can increase their reproductive fitness by mating with many females. Females, conversely, have been thought to benefit by remaining more demure. But now, a new study from the University of Western Australia on mice suggests that females, too, may reap the rewards of so-called promiscuity. In an “elegant experiment“, as described by Faculty Member Gabriele Sorci, researchers Renée C. Firman and Leigh W. Simmons show that females who sow their wild mouse pellets, so to speak, produce more viable offspring than their monogamous counterparts.

To reach this conclusion, the researchers bred 14 generations of mice in two lines: one monogamous, and one polyandrous. They then crossbred descendent mice in the following pairings: 1) maternal polygamy and paternal monogamy; 2) maternal monogamy and paternal polygamy; 3) maternal and paternal polygamy; and 4) maternal and paternal monogamy.

The results of these crosses showed that the polygamous lines produced greater litter size (6.65 ± 0.24) than their monogamous counterparts (4.94 ± 0.27), providing “the first transgenerational, empirical demonstration that post-copulatory sexual selection drives increased embryo viability in a vertebrate.” The authors’ previous studies also show that males from polyandrous lines have greater sperm quality and competitive edge than males from monogamous lines, results that dovetail with the “good sperm hypothesis.”

Firman and Simmons’ showed in the evaluated study that polyandrous reproductive success resulted from the mothers passing on supersperm genes to their sons, with no apparent effect on female offspring. In other words, these daughters of polyandry hit the reproductive glass ceiling, while the sons of promiscuity scaled the heights of reproductive superiority, ennobled by their genetically superior sperm.

Typical.

But girl-mice need not lament, as the authors declare, “We have provided one of the first empirical demonstrations in a mammal that polyandry can generate evolutionary increases in female fitness across successive generations.”

So what’s a modern female reproductively minded vertebrate to do with this knowledge? What she should not do, according to the recent and fantastically titled study, “Sexually extravagant males age more rapidly,” is shackle herself to the flashiest guy in the room.

The authors of the study examined reproductive decline in the Houbara bustard. They found that male bustards that invest the most in their trademark showy mating displays experience a more rapid decline in their spermatogenic function as they age, when compared with their less flamboyant peers. In his evaluation of the paper, F1000 Faculty Member Daniel Promislow writes,

This work demonstrates the important connection between sexual selection and aging, and suggests that female bustards need to consider more than just outward display when choosing mates.

Okay, so he sounds a little defensive. But he may have a point, at least for female bustards going for quality, not quantity. But if we are to believe Firman and Simmons’ studies, quality may follow quantity.

So keep dancing, bustards; the ladies are watching, and you’re looking good.