21 October 09, PM edition

Late day at work…

Are spiders really that different from humans? 🙂

Male spiders that saunter onto a female’s web after a rival has spent hours wooing her can quickly copulate without being prematurely eaten by the female. This tactic could lead to small spider suitors seeking out competition with larger rival spiders rather than avoiding it, Canadian researchers say.

The Australian redback spider (Latrodectus hasselti), a member of the black widow family, has a particularly deadly mating ritual. It is one of only a handful of spider species in which the males willingly and actively assist the females with sexual cannibalism — in which the female consumes the male after copulation. In the process of mating, the tiny redback male, whose 4-millimetre body is dwarfed by that of the centimetre-long female, inserts one of his two penis-like organs into one of the female’s two sperm-storage sacs. The male then somersaults to place his abdomen over the female’s mouthparts, and the female starts eating him as they mate.

The male is eventually completely consumed, but first, the female makes one of two choices. Either she lets the male inseminate her other sperm-storage sac, enabling him to father all her offspring before polishing him off; or, in an act of premature cannibalism, she gobbles him up then and there and waits for another mate. This decision, show Jeff Stoltz and Maydianne Andrade of the University of Toronto Scarborough in Ontario, Canada, depends on the length of time that the male spends courting the female before copulation commences.

Oh my, it looks grim for the male, right?

The researchers then staged competitions in which they allowed solitary males to get past the first phase of courtship and make contact, then introduced intruder males (see video). These latecomers, Stoltz and Andrade report in the journal Proceedings of the Royal Society B, could then mate after only 20-50 minutes of wooing without being prematurely eaten, thereby allowing less-fit males to get one up on their stronger rivals.

“It’s a very sneaky tactic that males are employing here to get around having to expend any energy in courting these females,” says Stoltz. “Females are unable or unwilling to discriminate the source of the courtship, and that provides the opportunity for other males to circumvent female choice.”

In other words, sex for less effort. Hey, the males are still eaten, but not prematurely.

Academia: if you write letters of recommendation, please avoid this pitfal:

In a standard letter of recommendation at the postdoc/faculty level, there is frequently a comparison to other successful scientists. The letter usually reads something like “reminds me of person X, Y, or Z at a similar level of their career” or “shows the same persistence and insight as person Q, and stronger big picture thinking than person P”. These comparisons are almost always favorable, saying that the applicant is in the same league as other people who are recognized as having had a significant scientific impact.

But, for some reason, some fraction of letter writers insist upon doing these comparisons only within a single gender, when the applicant is a woman. In other words, “(woman) X shows a similar level of insight as (woman) Y and (woman) Z”. I’m not saying that these comparisons are not favorable — they’re usually comparing a strong female applicant favorably with other successful female scientists. Their praise is genuine and well meant. However, one can’t but help perceive that they see women as somehow swimming in a different pool than the rest of the guys.


October 21, 2009 - Posted by | education, nature, science

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