The closest to Normal (Illinois) that I've ever been.

Sunday, September 9, 2007

The crickets

The question that I am most frequently asked is: why did you move to Normal? People usually ask this question with this uncomfortable kind of a cautiousness, as if they are expecting me to overshare some tragic personal event that led to my appearance here. When I say that I am here to do research, they perk up a little. However, when I tell them that I do behavioral research on crickets, they generally look at me as if I were crazy. Perhaps they assume that nothing short of research to solve the energy crisis/stop world hunger/cure cancer would justify moving from California to Normal. So what is my research about, anyway? Here's the short version:

It is usually assumed that males benefit more from mating with many females than females benefit from mating with many males. However, we now know that females that mate with different males can gain benefits from doing so, including having offspring that are more genetically diverse. In one part of my PhD research, I found that female field crickets prefer to mate with new males rather than previous partners. Further, females bias sperm use to favor novel males over previous partners.
I am now working at ISU in a lab that uses decorated crickets to address similar questions. Previous work in Scott Sakaluk's lab found that female decorated crickets identify and avoid previous partners by marking the males with their own scent. I will be investigating the female scent cues, as well as whether males use similar scent cues to identify previous female partners. So, no, my research will not save the world (unless the earth is overrun my giant alien cricket overlords), but it will provide info about the evolution of behavior.

Grylllodes sigillatus mating; hypothetical giant alien insect overlords


Jessica Malisch said...

Ohh I do enjoy some cricket sex blogging on a Sunday:)

Susan said...

Don't we all...

JPGoldberg said...

I'm just wondering how big of a maternal investment into off-spring the mommy crickets put in compared to the paternal investment of the daddy crickets. If the difference isn't very large then shouldn't we expect less asymmetry in sexual behavior?

On another topic, there was an essay in the New York Times in the middle of August criticizing reports that human males have more sex partners than human females. The argument was the simple mathematical one that the average number of heterosexual partners must be the same for males and females.

I didn't look at the research the article referred to but my suspicion is that someone confused mean and median. Is that your take on things (if you are familiar with the essay I'm talking about)?

Anonymous said...

That is such a funny picture of cricket lore. Susan your sense of humor is unsurpassable. xo

Susan said...

Hi Jeff,
True that female crickets don't have to do as much for their offsping as some species. However, if you crunch the numbers, a female can lay as many as 1000 eggs in her lifetime. A male, mating once a night for three weeks could potentially mate with 21 females. If the male was unimpeded by other males, he could potentially father 21000 offspring. The difference in male versus female behavior can be due to physiological limitations that make mating with different partners more important to males than females. As a counter-example, in katydids, males make a large nutritive gift for females, which takes males several days to produce, and limits male mating rate. In these species, females compete for access to males, because the number of offspring that can be produced is limited by the number of nutritive gifts that a female can collect.

On the other topic, in crickets (and perhaps people), it is predicted that there will be a higher variance in male mating success than in female mating success: most females can mate as often as they want to, however some males are able to mate with many females and some males not so much. Re: the NYTimes article, it is mathematically possible that the median number of sexual partners for males and females could be different, however, I suspect that there is more to it than that. Although males and females are predicted to have different variances in numbers of partners, there is no reason to predict that the median (and mean) should differ among the sexes. If you are interested, I found this article on estimation of sex partners for some alternative hypotheses: