Peacocks’ tails and fireflies’ bums: Resolving the lek paradox

This week’s post is a guest contribution by Tom Houslay, a doctoral student at the University of Stirling in Scotland who studies sexual selection. Tom blogs about insects, sex, and evolution at his personal website, which would be totally NSFW if you were a sage grouse. If you have an idea for a post, and you’d like to contribute to Nothing in Biology Makes Sense, e-mail Jeremy to inquire.

Firefly

Male fireflies emit species-specific patterns of light flashes as they fly – these patterns are answered by receptive females, enabling the males to find them. Image courtesy Rick Lieder

Whenever I read the Dobzhansky quote from which this blog takes its name, it puts me in mind of another famous phrase:

“The sight of a feather in a peacock’s tail, whenever I gaze at it, makes me sick!”

Such were the words of Charles Darwin in correspondence with botanist Asa Gray in 1860, a year after the publication of On the Origin of Species. Taken at face value, it is easy to see why Darwin felt such discomfort when gazing upon a peacock’s feathers—if animals adapt to their environment, surely a cumbersome train of colourful feathers would be counterproductive? Not only should it attract the attention of predators, but it would surely impede any attempts to evade them.

ResearchBlogging.orgWhile peacocks are the posterboys for such traits, they are far from the only offenders. Time and again in the animal kingdom, we see exaggerated ornaments, vibrant colours, and fantastic acoustic and visual displays. Frogs and crickets advertise their whereabouts with loud calls, fireflies flash patterns with bioluminescence; greater sage grouse strut brazenly in open pastures. While they undoubtedly brighten up the world around us, these behaviours and morphologies can seem not only unnecessary, but downright detrimental to the survival of an individual. How, then, can their existence be resolved with our knowledge of evolution? Furthermore, why are these characters generally seen only in the males of a species?

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Friday coffee break

Coffee flasks

Siphoned coffee.

Every Friday at Nothing in Biology Makes Sense! our contributors pass around links to new scientific results, or science-y news, or videos of adorable wildlife, that they’re most likely to bring up while waiting in line for a latte.

From Sarah: Psychological studies suggest thankfulness is good for your mental well-being.

Research by McCullough and others finds that giving thanks is a potent emotion that feeds on itself, almost the equivalent of being victorious. It could be called a vicious circle, but it’s anything but vicious.

From Devin: An alternative to the academic tenure-track could be research institutes, with shorter-term contracts.

Remove the security blanket of tenure, says [Sean] Eddy, and he is driven to work harder, and to assess his research programme more frequently to make sure that it is still on the right track. Furthermore, he says, tenure, which is especially coveted in the United States, brings its own job-related anxieties. “If I’m tenured at Washington University or anywhere, they can’t fire me, but they can put me in a closet and take away my space,” he says. “I prefer it this way — I think it’s appropriate to have a little fire under you.”

From Jeremy: Turns out The Lord of the Rings is about getting a Ph.D.

After Frodo has completed his first project, Gandalf (along with head of department Elrond) proposes that the work should be extended. He assembles a large research group, including visiting students Gimli and Legolas, the foreign postdoc Boromir, and several of Frodo’s own friends from his undergraduate days. Frodo agrees to tackle this larger project, though he has mixed feelings about it. (“‘I will take the Ring’, he said, ‘although I do not know the way.'”)

My gut microbiota made me do it!

Our bodies are teeming with bacteria: for every one human cell in your body, there are at least 10 microbial cells. That’s about 100,000,000,000,000 microbes – what are they all doing?

The communities of microorganisms that live on or in a particular host are called the microbiota, and are responsible for a lot of physiological and biochemical functions. It’s probably no surprise that the gut microbiota digest complex molecules we’ve eaten and they keep pathogens from colonizing our bodies (most of the time). They synthesize vitamins and amino acids that we can’t make ourselves. Recent studies have shown that variation in gut microbiota are associated with obesity, diabetes, normal brain development and insulin signaling (which has a downstream affects on body size and developmental rate). But there’s one effect that variation in microbiota can have on their host that is particularly fascinating to me: they can influence host mate choice.

In 1989, Diane Dodd reared fruit flies (Drosophila pseudoobscura) from a common stock on two different food sources: starch and maltose. She found that after multiple generations of isolation on their separate substrates, starch-flies preferred to mate with starch-flies and maltose-flies preferred to mate with maltose-flies. The result was robust and repeatable, but the reason why and its mechanism were unknown.

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Friday coffee break

Musical coffee

Every Friday at Nothing in Biology Makes Sense! our contributors pass around links to new scientific results, or science-y news, or videos of adorable wildlife, that they’re most likely to bring up while waiting in line for a latte.

From CJ: The New Yorker covers recent work on genetic evidence that ancient humans knocked boots with Neanderthals. So to speak.

Once the Neanderthal genome is complete, scientists will be able to lay it gene by gene—indeed, base by base—against the human, and see where they diverge. At that point, Pääbo believes, an answer to the age-old question will finally be at hand. Neanderthals were very closely related to modern humans—so closely that we shared our prehistoric beds with them—and yet clearly they were nothumans. Somewhere among the genetic disparities must lie the mutation or, more probably, mutations that define us. Pääbo already has a team scanning the two genomes, drawing up lists of likely candidates.

From Devin: A new study analyzes cross-cultural variation in musical styles using a method analogous to the way biologists analyze genetic variation among and within populations.

We attempt here for the first time to quantify both components of cultural diversity by applying the AMOVA [Analysis of MOlecular VAriance] model to music. By employing this approach with 421 traditional songs from 16 Austronesian-speaking populations, we show that the vast majority of musical variability is due to differences within populations rather than differences between. This demonstrates a striking parallel to the structure of genetic diversity in humans. A neighbour-net analysis of pairwise population musical divergence shows a large amount of reticulation, indicating the pervasive occurrence of borrowing and/or convergent evolution of musical features across populations.

(Devin also notes that this sounds rather like Ishkur’s Guide to Electronic Music.)

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Tell Congress to increase NIH funding

For your consideration: a Change.org petition asking the U.S. Congress to increase funding to the National Institutes of Health by 3% in next year’s Federal budget. NIH is one of the biggest sources of public research funds in the U.S., and its support goes well beyond things immediately connected to human health and medicine—I did many analyses for my dissertation research on Joshua trees and yucca moths on a supercomputing cluster supported, in large part, by NIH funds.

Some would argue that the private sector should take over some of the lost funding for academic, basic research. The sad fact is that the private sector does not support the type of basic research that the NIH does; they take the results NIH-funded research and apply it to drug development. In addition, many entities in the private sector are currently slashing their Research & Development (R&D) budgets! For example, Pfizer recently cut its R & D budget by 1.5 billion.

Consider the following numbers. For 2011 budget, U.S. spending on:
Social security was $2564 per citizen (20.8% of the budget)
Defense was $2203 per citizen (18% of the budget)
Medicare was $1569 per citizen (12.8% of the budget)
Medicaid was $1172 per citizen (7.8% of the budget)
NIH was $99 per citizen (0.8% of the budget)

The original idea, as I understand it, is for this to be an “open letter” to Congress from working scientists across the nation, but supportive non-scientists should definitely sign on, too.

A post on one of biology’s most confounding riddles: the latitudinal gradient in biodiversity.

A beautiful, but comparatively species poor forest in eastern Oregon

Explaining global patterns of biodiversity is a fundamental goal in biology. Understanding how the tens of millions of species on earth have arranged themselves into populations, communities, and ecosystems, is critical for conserving them in the face of a rapidly growing human population and global climate change.

ResearchBlogging.orgThe latitudinal gradient in species diversity is perhaps the most famous such pattern, and it has confounded biologists for decades. Almost invariably across taxonomic groups, hemispheres and continents, as one moves from polar regions towards the equator, species diversity increases (see the figure for a depiction of global bird diversity). The concept of diversity here can be broken down into three parts: “alpha diversity” or the diversity of species in a single location; “beta diversity”, or the turnover of species observed when moving among locations; and “gamma diversity” or the diversity of species found in an entire region. The latitudinal diversity gradient holds true for all three elements.
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Friday coffee break

Coffee flasks

Siphoned coffee.

Every Friday at Nothing in Biology Makes Sense! our contributors pass around links to new scientific results, or science-y news, or videos of adorable wildlife, that they’re most likely to bring up while waiting in line for a latte.

Welcome to the blogosphere: evolvevit! by Amy Dapper, and Simon’s Science by Simon Boardman.

From Sarah: The New York Times has a slideshow from Carl Zimmer’s new collection of science-y tattoo images.

From Luke: People with natural resistance to HIV infection have white blood cells that are more vulnerable to the virus—but they don’t produce many viruses once infected.

Using multiple methods of infection and both single-cycle and replication-competent virus, we show that unmanipulated CD4(+) T-cell populations from ES [resistant patients] are actually more susceptible to HIV-1 infection than those populations from CP [nonresistant patients]. Depletion of highly susceptible cells in CP may contribute to this difference. Using 7AAD and AnnexinV staining, we show that infected cells die more rapidly than uninfected cells, but the increased death of infected cells from CP and ES is proportional. Finally, using an assay for measuring virus production, we show that virus production by cells from CP is high compared with virus production by cells from ES or uninfected donors.

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What to do for patients who don’t feel like themselves?


As a third year medical student, I am required to prepare various evidence-based medicine projects related to patients that I see during a given rotation.  Rotations are where I get the opportunity to see patients in the hospital in various specialty settings and apply the knowledge that I have acquired during the first two years of my medical education.  My first rotation was psychiatry, where I met an adolescent girl with a very interesting diagnosis.  The diagnosis was depersonalization disorder (DPD).  This diagnosis and its potential treatment are the focus of my post this week.  I investigated the current pathophysiologic theories along with current pharmacologic ideas for treatment.

ResearchBlogging.orgDPD is characterized by an altered perception of self in which an individual experiences detachment from his or her body and personal memories, emotional and physical numbing, and a sense of living in a dream-like state.  DPD patients often feel as though they are watching things happen to them. They do, however, remain aware of this unreality and feel like something is wrong with them (1).  They can have a tendency to resort to extreme measures, such as cutting, in an attempt to “feel” and overcome the sensation of numbness.

There are currently no definitive treatments that have been developed regarding DPD.   This is due largely to the fact that there is no well-defined pathology regarding its onset.  Given its estimated prevalence of 0.8-2.0% in the general population, it is about as widespread as schizophrenia.   Yet little research has been done to understand its root cause and treatment (1).  Despite the epidemiologic studies that have shown this prevalence rate, it is still assumed to be rare and associated with other anxiety or psychotic disorders instead of being a primary condition on its own.

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Friday coffee break

Cane toad

A cane toad would probably like its coffee with a side order of cane toad.

Every Friday at Nothing in Biology Makes Sense! our contributors pass around links to new scientific results, or science-y news, or videos of adorable wildlife, that they’re most likely to bring up while waiting in line for a latte.

From Sarah, a great New York Times article on cannibalism in the animal world:

Life after metamorphosis brought scant relief from fraternal threats. The scientists also demonstrated that midsize cane toads wriggle digits on their hind feet to lure younger cane toads, which the bigger toads then swallow whole. “A cane toad’s biggest enemy is another cane toad,” Dr. Shine said. “It’s a toad-eat-toad world out there.”

From Devin, a study that shows how epidemiologists can predict the spread of diseases through human social networks by tracking three properties of those networks:

For networks of intermediate density, different structural attributes have a profound impact on disease behaviour. By including the clustering coefficient and mean path length along with the mean degree of the contact network, we can reduce the uncertainty of our model predictions of disease performance (by nearly 14%).

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Eek! The notion of outgoing sex-a-thon specimens living blithely!

Biologist Jon Wilkins, author of Lost in Transcription and the webcomic Darwin Eats Cake, gives us a nice welcome to the blogosphere, and reminded me that the gang at Darwin Eats Cake took on the Dobzhansky quote behind our name …

Nothing in biology makes senseJon also addressed the origins of the epigram in some detail, which is an interesting read.