Aggressive females get the mate: study
CHICAGO (AFP) — Aggressive female antelopes are more likely to get a mate even when they go so far as to charge at the male to stop him from having sex with a rival, a study released Thursday found.
But while the males may be turned on by this behavior the first few times, they eventually get angry and will even lock horns with the females to make them to stop pestering them, according to the study published in Current Biology.
The discovery shows that the common understanding of sexual behavior -- that females are docile and choosey and males are aggressive and eager to mate with anyone -- is too simple for the real world.
"When biologists talk about the 'Battle of the Sexes,' they often tacitly assume that the battle is between persistent males who always want to mate and females who don't," said Jakob Bro-Jorgensen, a Danish biologist based at the Zoological Society of London.
This is not the case among the topi antelopes of Kenya, Bro-Jorgensen found after careful observation.
That's because the females mate repeatedly with an average of four males in order to ensure impregnation during a daylong ovulation period.
They prefer to mate with the larger, stronger males who win the coveted territory in the center of the mating areas.
These males are so popular that they mate as often as 22 times per 30 minute period during the height of the month and a half long rutting season.
And, perhaps unsurprisingly, conflicts break out when two females entered the high-rent territory these males occupy.
"It's like watching a soap opera," he said in a telephone interview from his London office.
If both females arrive at the same time, a fight will often ensue until one asserts her dominance and forces the other female out.
But if a dominant female arrives while the high-status male is in the midst of copulating, she will often interrupt him rather than wait for him to be done in order to ensure better access to his depleting sperm supplies, Bro-Jorgensen concluded.
"Typically, the female will lower her horns and run at the male," he said.
"Often the male will jump out of the way but occasionally she'll clip him and sometimes the male will get angry and turn on her."
While this is risky behavior, it often works out in her favor.
"It doesn't happen that he immediately turns around and mates with her, but it makes it more difficult for him to mate (with others) and more likely that he'll say 'oh what the hell' and mate with her."
Interestingly, the males were more likely to spurn the aggressive females if they had already mated repeatedly with them.
While this aggression should signal that the dominant females were more likely to produce viable offspring, it was not enough to offset the male desire to spread his genes as widely as possible, Bro-Jorgensen concluded.
The majority of the females were also willing to mate with the lower-status males either because they have been harassed or wanted to cast a wider net.
But they copulate more frequently with the males in the center, probably in order to give the high-status sperm a better shot at fertilizing their egg, Bro-Jorgensen concluded.
He laughed when asked if the behavior was similar to that of a pub at closing time and said that while it may be an apt comparison, human behavior was more complex.
"One of the key factors that causes this reverse sexual conflict is that females mate many times and that is not normal in humans," Bro-Jorgensen said.
"But what is common is the strong female preference for a few males that creates competition among females."
