GELLERMAN: Coming up, lovebirds, an unusual pairing. But first, love role reversal in this Note on Emerging Science from Alexandra Gutierrez.

GUTIERREZ: Female topi antelope don't like playing hard to get. They're not into prolonged courtship rituals, and they don't really like monogamy, either. In the battle of the sexes, these antelope essentially reverse the rules of engagement.

The standard assumption in sexual selection theory is that a male will aggressively pursue a female. But Finnish scientists observed that Topi behavior goes counter to that assumption. Researchers have noticed that female topis persistently – and sometimes violently – attempt to attract the best mate.

Because these females are only fertile for one day, they do not have the luxury of waiting for the best male to choose them, say the scientists. They must instead compete for the attention of the strongest males in order to improve their chances of getting pregnant. The fact that the males' sperm supply is limited further puts pressure on the females to find one good partner, or sometimes even a few.

While it could be argued that the topi males are in an enviable position, being such an object of desire can be tiring and even dangerous. Males will sometimes collapse from exhaustion as a result of this attention, and they must occasionally fight off females who can be a bit too domineering. So it seems that in the Topi world, love can hurt.

That's this week's note on Emerging Science. I'm Alexandra Gutierrez.