News — Picture it: One jerk in a bar spends the night delivering bad come-ons to women. By the end of the evening, the women aren鈥檛 receptive to even the nicest guys around. It鈥檚 a scenario with a basis in evolutionary theory. Males increase their fitness by acquiring more mates; however, this is often not the case for females 鈥� and therein lies the conflict.
Researchers at Binghamton University and the University of Arizona studied sexual conflict in water striders, an insect that鈥檚 a common model system. They found that, given a choice, females will group themselves around the gentlemen.
The results of the groundbreaking experiment 鈥� in which the insects had a freedom of movement not possible in most studies of sexual conflict 鈥� appear in the Nov. 6 edition of the prestigious journal Science.
鈥淭he original title of the paper was 鈥楴ice Guys Don't Always Finish Last,鈥欌�� lead author Omar Tonsi Eldakar said. 鈥淚 find that statement to be quite descriptive of the project.鈥�
Previous studies of sexual conflict generally have limited individual movement, emphasizing local competition, noted Eldakar, a 2008 PhD graduate of Binghamton University and a post-doctoral fellow with the Center for Insect Science at the University of Arizona.
Eldakar said he perceives sexual conflict as an example of the 鈥渢ragedy of the commons,鈥� a situation in which the most exploitive strategy benefits the individual at the expense of the group. (The classic example is of a shepherd who adds another animal to his herd even though the shared pasture is overgrazed.) Few researchers have framed sexual conflict in these terms; however, Eldakar sees a parallel between that shared pasture and the availability of females.
鈥淲hen you pit exploitation against prudence in direct competition over a shared resource, you鈥檙e putting them into a scenario that favors the short-term, exploitative strategy, making it difficult to observe the advantage of prudence,鈥� he said. 鈥淭his does not accurately reflect what occurs in natural populations. But given a choice, females look for a way to get away from persistent males. If you allow individuals to self-organize, females find these nice guys and group around them, changing the landscape of competition.鈥�
Eldakar and his colleagues have shown through previous studies that groups in which a more gentlemanly approach to mating prevails do better on the whole, even though jerks generally outperform the nice guys when they have to compete one-on-one.
Eldakar thought of the insects as 鈥渘ice guys鈥� vs. 鈥渏erks;鈥� his adviser, David Sloan Wilson, a co-author of the paper and a distinguished professor of biological sciences at Binghamton, termed them 鈥済entlemen鈥� vs. 鈥減sychopaths.鈥�
鈥淭he presence of psychopaths dramatically reduced the productivity of the population,鈥� Wilson said. 鈥淲hen all the males were gentlemen, the females laid about three times more eggs than they did when all the males were psychopaths. And yet within each group the psychopaths were doing better than the gentlemen. How do the gentlemen persist if they鈥檙e disadvantaged within the group?鈥�
Once the females could move between groups, the researchers had their answer. Eldakar and Michael J. Dlugos, then also a Binghamton graduate student, devised a wading pool equipped with special doors that could restrict movement between groups or allow the insects to move freely.
鈥淲hen they opened the doors, the females would leave whenever a psychopath came around,鈥� Wilson said. 鈥淭he whole thing resulted in a heterogeneity in which the females were clustered with the gentlemen. It鈥檚 the movement of individuals that creates these differences between groups that favor nonaggressive males.鈥�
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