Termite toots causing global warming?

Termites to blame for global warming?

I was, um, in the bathroom at the Denver Zoo listening to the info feed the nice woman with the colonial accent was providing for folks using the facilities. The facts are all about poop and related activities, which I suppose is appropriate to the moment at hand. To add to the excretory atmosphere, the stall doors bear representations of animal hindquarters. Just letting you know that in case you ever want to stare at a close-up view of a baboon’s rear while you’re micturating. At any rate, as I was washing my hands, I heard a little tidbit about termites and greenhouse gases. The pleasant voice informed me that termites contribute a good percentage of the world’s greenhouse gases to the atmosphere, in the form of methane. Tooty little buggers, they must be.

It’s true. More methane than cows

Like most animals that survive on cellulose-based diets, termites have friendly micro-organisms that help them break down normally undigestible macromolecules. In the process, the micro-organisms produce a lot of methane gas. That gas, whether it’s in a cow or a termite, has to go somewhere, and that somewhere is out. Contrary to what some people may think, and according to the pleasant voice at the Denver Zoo, termites expel more of this stuff than cows do.

Should we blame the bacteria instead?

Actually, the helpful gut micro-organisms in termites are not all bacteria. Some are protozoans, depending on the termite species. But they’d be nothing without their hosts, so I guess we can just go ahead and blame them both. And I blame the Denver Zoo and their scatalogically oriented bathroom experience for the existence of this particular blog post.

Should we kill all the termites?

Well, that’s a terrible idea for any number of reasons, but as it turns out, it’s also not gonna help. One of the primary poisons used to knock of the wood-chewing insects happens also to be a “powerful greenhouse gas.” In addition, termites serve as a model for efficient harvesting of energy from biofuels, pulling about 90% from what they take in, compared to humanity’s sadly low success rates. So, yes, they eat our houses and expel about 15% of the methane in the atmosphere, but…they’re still better than we are at efficiently extracting energy from what they take in.

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The mysterious reproductive life of the giant panda

Photo credit: Mehgan Murphy, Smithsonian’s National Zoo

National Zoo’s giant panda had pseudopregnancy

National Zoo officials announced today that Mei Xiang (link has Panda Cam!), who had been monitored for several months for pregnancy, was not pregnant after all. Instead, she was experiencing a common feature of panda endocrinology, the pseudopregnancy.

Panda pseudopregnancy a common event

How could officials not be sure for months about whether or not the pregnancy was real? Panda pseudopregnancy so perfectly mimics an actual pregnancy that even hormone levels follow those of a real gestation. Staff had been monitoring her by ultrasound and blood testing, and even though ultrasound had yet to show a viable fetus, whether the pregnancy was real or pseudo was not confirmed until the hormones wrote the final chapter.

Pseudopregnancy hormones like pregnancy hormones

Late this month, Mei Xiang showed a drop in progesterone hormone. When hormone levels hit baseline in a possibly pregnant panda, one of two things can happen: a birth, or confirmation of pseudopregnancy. The progesterone decline set the clock on a 24-hour watch to see if Mei Xiang would bear a cub. She didn’t.

Ovulation once a year!

Giant pandas ovulate only once a year. Regardless of whether conception occurs, the female panda will appear pregnant, behave as though she is pregnant, and register the hormone patterns of pregnancy. If conception does not occur in that one annual opportunity, a female panda will almost always enter into a pseudopregnant state. Mei Xiang has done that five times. She’s also experienced a genuine pregnancy, bearing a cub in 2005 that now lives in China as part of a panda breeding program.

Panda soon to be back for public viewing

Mei Xiang has been sequestered during her pseudopregnancy, but her habitat at the zoo will now open again for public viewing. During her pseudopregnancy, her behaviors included reduced activity and appetite. These are now both expected to increase.

For your consideration

Pandas have some unusual life history strategies, including being food specialists and often accidentally suffocating their offspring. And, it appears that many ovulations result in pseudopregnancy. What might be an explanation for why pandas are so prone to entering a pseudopregnant state if conception does not occur? Could the behaviors that accompany the pseudopregnancy have anything to do with it?

In pandas, the hormones of a pseudopregnancy are similar to those of a real pregnancy. What pathways underlie the female’s production of these hormones of pseudopregnancy?

Women can also experience pseudopregnancy, sometimes referred to as “hysterical pregnancy.” It can even involve abdominal distention and in some cases, hormonal changes. What are some of the physiological underpinnings of a pseudopregnancy in women?

Finally, dogs and mice are also known for having pseudopregnancies. Do you think the pressures that result in these pseudopregnancies are similar to those that result in a false pregnancy in the panda? Why or why not?

Can rain make buffalos have boys?

African buffalo shift sex ratios with rain

African buffalos (Syncerus caffer) have more males during the rainy season in Kruger National Park, and it’s not just a random accident of fate. Researchers have found that specific sequences on the Y chromosome are correlated with seasonal differences in birth sex ratios in the buffalo population.

X sperm vs. Y sperm

Does that mean that rain somehow makes buffalos have more boys? Not directly. Instead, it may come down to a DNA-level battle royale involving the Y chromosome. Sometimes, sperm carrying the Y win the race to the egg, while at other times, X-carrying sperm are the victors. These times correlate with higher frequencies of certain sequences, or haplotypes, of the Y chromosome occurring in the population, with one sequence being much more common during the rainy season, when more males are born.

Selfish genes gone rogue

The investigation suggested the existence of a suppressor of Y chromosome success acting during the dry season, when females birthed more females, and a distorter in favor of Y chromosome success in the rainy season, when more males are born. The distorter may shift meiosis in favor of the Y-carrying sperm or disrupt survival of X-carrying sperm. Interestingly, distorters are not considered to act for the benefit of the individual carrying them and are considered “selfish genes.” Suppressors…well…suppress the distorters. The authors refer to these apparent Y chromosome suppressor/distorter regions as sex-ratio, or SR,  genes.

Dry season not a good sperm season

They also noted that during the dry season, buffalo didn’t make as much sperm, and the sperm they did make weren’t as frequently normal looking or very good swimmers. They hypothesize that semen quality may interact with the decreased availability of food in the dry season, leading to drop in Y haplotypes associated with a male-biased sex ratio. The investigative team, whose lead author, Pim van Hooft, is based at Wageningen University in The Netherlands, also suggested that the SR genes may be present in other species, adding a new dimension to the increasingly complex mechanisms of sex ratios in mammals.

For your consideration

1. Sex determination in vertebrates happens in a number of different ways. Some mechanisms don’t involve sex chromosomes at all but instead rely on environmental cues. Find an example of a species that uses environmental cues to determine sex. How can an environmental trigger be similar to a chromosomal trigger as a sex determinant? How do they differ?

2. Many species have life history strategies that involve adjusting sex ratios. What are possible explanations can you find to explain how adjusting sex ratio might benefit a species? How might it be a potentially dangerous gamble?

3. Distorters in general appear to be doing their host individual no favors. Given that fact, what is one explanation for the existence and persistence of suppressors of distorters?

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