Hopefully, Not The Next Species Crossover

[Harold Gough]

Selectivity we don't want to see in a pandemic!

http://www.sciencedaily.com/releases/20 ... 121801.htm

Harold

[Mike B in OKlahoma]

I wonder what advantage their is to the infection agent in targeting males? I wonder if it is truly exclusive to males, or just mostly infects males for some reason?

[rjlittlefield]

Much has been written about Wolbachia. For introduction, see the article in Wikipedia and the first reference listed there.

--Rik

[Mike B in OKlahoma]

I spent some time on this, the place where I was most easily hit over the head with the "answer" was actually in the Wikipedia article on intragenomic conflict....Do I understand that the reason for doing away with males is that males are useless to the Wolbachia infection for reproduction, so Wolbachia tries to introduce effects to reduce the percentage of males in the host population?

[Mike B in OKlahoma]

Selectivity we don't want to see in a pandemic!

I certainly wouldn't care for this, though if you were a male who was somehow resistant, the social life could be fun for awhile!

[rjlittlefield]

Do I understand that the reason for doing away with males is that males are useless to the Wolbachia infection for reproduction, so Wolbachia tries to introduce effects to reduce the percentage of males in the host population?

Sort of, but not quite. The issue raised in the intragenomic conflict article is not just that the males are "useless", but that killing them actually increases the survival and reproduction of females infected with the same strain. "In the case of embryo death, this diverts investment from males to females who can transmit these cytoplasmic elements (for instance, in ladybird beetles, infected female hosts eat their dead male brothers, which is positive from the viewpoint of the bacterium)." Under these conditions, an individual bacterium that mutates to kill males will reproduce more effectively on average than its competitors who do not.

However, it's important to note that these are pretty restricted conditions. A bacterial strain that suicides by killing its male hosts can only benefit if a) those suicides provide more value to their siblings than to other less related bugs, and b) the hidden costs of suiciding in males are sufficiently small to be overcome by the benefits. By "hidden costs", I'm referring to things like erroneous suicides where the bacterium makes a mistake in determining the gender of its host. If the benefit of suiciding in a male host is less than the cost of erroneous suicides and whatever else goes on in females, then a male-killing strain will die out instead of becoming predominant.

The fact that we're surprised to see this sort of selectivity implies that it is uncommon. Compare this to Wikipedia's statement that "One study concludes that more than 16% of neotropical insect species carry this bacterium." It seems that the magic combination of a) and b) is pretty rare.

--Rik

[Mike B in OKlahoma]

The fact that we're surprised to see this sort of selectivity implies that it is uncommon. Compare this to Wikipedia's statement that "One study concludes that more than 16% of neotropical insect species carry this bacterium." It seems that the magic combination of a) and b) is pretty rare.

What?! You mean I can't blindly accept everything in Wikipedia? I'm shocked, shocked!!!

It's also possible that either there's something special about the neotropical environment that makes this a more viable way of life than in the moderate climates that are more familiar to most of us.....Or maybe it is just fairly common in insects, but we just don't know about it--Either science as a whole, or that just the people who aren't specialists in insect parasitology--I consider myself fairly knowledgeable about insects, and I can convince any civilian that I'm a great expert on 'em, but I didn't have a clue about this.

However, I suspect you are right, and the key word is "one study". Individual studies shouldn't be depended on for sweeping statements like that....

[rjlittlefield]

The fact that we're surprised to see this sort of selectivity implies that it is uncommon. Compare this to Wikipedia's statement that "One study concludes that more than 16% of neotropical insect species carry this bacterium." It seems that the magic combination of a) and b) is pretty rare.

What?! You mean I can't blindly accept everything in Wikipedia? I'm shocked, shocked!!!

I think that what you heard is not what I intended to say.

I have no reason to think that Wikipedia's statement is wrong, or that the study was not representative.

My point was rather that Wolbachia in one form or another is quite common, while the selective killing of males at levels sufficient to be seen in population studies is considered noteworthy.

--Rik

[Mike B in OKlahoma]

Ah, okay....Yep, I got entirely the wrong message!