Month / February 2011

by Roslyn

A case of mistaken celebrity

They all look the same to us. Celebrities, that is. And by us, I mean academics.

The proof starts with peacocks. Last fall, I was working on some measurements I took of the crest ornament in these birds. Peafowl have this funky little fan of feathers on top of their heads, and though it’s not that small in the grand scheme of fancy bird plumage ornaments, the peacock’s five centimetre crest looks a bit ridiculous next to the metre-and-a-half long train.

Why bother having a crest when you also have a big train? And why do females wear crests too? In this species, the crest appears to be the only plumage ornament shared by both sexes. Here are some of my pictures from the field, taken on the cusp of the breeding season:

Crest ornaments of male and female peafowl

Crests of (a) male and (b-c) female peafowl. Scale bars are 10 cm. Photos by Roslyn Dakin.

Over the years, I’ve measured the crests of close to 150 birds. These data lend some support to the idea that the crest is a signal of health in both males and females, although it might work in slightly different ways for the two sexes1. As you can see from the picture above, there is a lot of variation in how the crests look – and it’s mostly on the female side of the equation. Almost all adult males have tidy looking crests like the one shown in (a), but females often have crests with a lot of new feathers growing in (c). It turns out that males in better condition tend to have fuller, wider crests. The healthiest females, on the other hand, have crests that look most like those of males, with all feathers grown out to the top level (b).

The extreme variability among females leads to an additional hypothesis, and it’s one that I can’t rule out at this time. Perhaps the crest is a signal of individual identity that the birds use to sort out who’s who in their social groups – just as faces do for us. A clue that this could potentially work for peahens is that my field assistants and I can do it. Once you spend enough time hanging around with these birds, you find yourself recognizing certain females that haven’t been captured yet (and that therefore lack identifying leg bands). Your first clue? Usually a unique pattern of crest feathers.

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by Roslyn

The winning score

As Hollywood gets dolled up for the Oscars, fans at home might surprised to learn that a field biologist could tell us a thing or two about the winning films. Dan Blumstein, a behavioural ecologist who works, quite fittingly, at UCLA, is an expert on yellow-bellied marmots. He might also be the person to turn to if you want to predict the win in the “Best Original Score” category this weekend.

Although Blumstein does most of his work with wild marmots in the Rocky Mountains of Colorado, studying several facets of their behaviour and evolution, he recently published a paper on the science of movie soundtracks1. With Richard Davitian and Peter Kaye from the School of Music at Kingston University in the UK, Blumstein applied techniques from his research on marmot vocal communication to an entirely new question: why are Hollywood moviemakers so good at manipulating our emotions? The results pick up on a common theme in the way humans and other animals use sound.

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by Roslyn

A royal waste?

Giant pandas are in the news again, this time for their annual date night at the Smithsonian National Zoo in Washington DC. But hardly a day goes by without a report somewhere on the latest captive panda birth, strategic breeding attempt or panda relocation.

A blogger at the London Review of Books compared the bears to members of the British royal family: both are suffering from shrinking ecological niches and in serious danger of extinction, hanging on by virtue of their marketing potential. The similarities don’t end there. Giant pandas, like royals, are expensive to house, with a fee of over $1 million per year for a zoo to lease a pair from China. Naturally, the breeding activities of giant pandas are as intensely scrutinized as those of Prince William.

This entails some surprising efforts when it comes to the pandas. The history of captive breeding for Ailuropoda melanoleuca is no sordid royal affair. It’s long, and for the most part, pretty unfortunate; zoos have been failing to produce heirs to the panda legacy for decades.

For starters, it’s nearly impossible to get the bears to mate in captivity, and it’s not just their deficiency in the looks department, as comedian Mike Birbiglia suggests. Captive pandas can’t seem to figure out a working sexual position1. Females often start things off all wrong by lying down, but the males are just as clueless. This led to panda porn: zoos started making videos of pandas achieving copulatory success, as training tools for the more hapless bears2. Other attempts to use Viagra on pandas were less encouraging, but the porn worked – for females as well as males – leading to a boom in captive births in recent years3.

Giant panda cub

Visitors can pay to see the cubs at the Chengdu giant panda breeding centre. File photo modified from newssc.org.

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by Roslyn

Groupthink

Which animal would use Facebook most, if it could?

My poll in class last week was a popular one – a fact that I couldn’t properly enjoy, since Charlie came up with it for me in a fit of brain-dead incapacity. Charlie’s Facebook question elicited chirps of excitement, compliments and even a few drawings on the response sheets. Here are the results, ranked by favour among the students:

  • Chimpanzees: So they have opposable thumbs, and can “use the spacebar” (is this actually important in Facebook?). A number of students gave bonobos special mention, since they would probably want to keep track of all their casual sexual relationships.
  • Dolphins: Highly intelligent, social, and they might also be interested in monitoring multiple sexual conquests. Dolphins and migratory whales could use Facebook to keep in touch while roaming widely over the oceans – the long-distance relationships of the animal kingdom. For some reason, students in different tutorial groups who chose dolphins were inspired to draw them for me as well. Coincidence?
  • Parrots and other birds: Especially in species that have high levels of extra-pair paternity, birds could use Facebook as a form of mate-guarding to keep tabs on their social partner1,2. There are other reasons to think that songbirds might easily make the transition to internet gossip. Female black-capped chickadees, for instance, eavesdrop on the outcome of song contests between rival males, and use this information when deciding on a mate3.
  • Eusocial animals: Like ants or naked mole rats (the only known eusocial mammal). A couple of students also mentioned highly social meerkats, since living in groups of 10-40 individuals would require them to keep track of a lot of social information.
  • Other yappy follower-types: hyenas, seals, lemmings, and Yorkshire terriers all got a mention.

Charlie and I discussed it over dinner at the Iron Duke. My first thought went to ants, for their extreme group lifestyle. The problem is that ants don’t really care about what other ants do or think about each other. Insect sociality is all about the greater good: worker ants toil away for the colony despite having no hope of reproducing on their own. Ok, so maybe the internet isn’t conducive to real reproduction either, but ants just don’t have the ego required. Plus, as one clever student pointed out, a colony of eusocial animals are all very close genetic relatives of one another – and she tends to block family members from Facebook.

Charlie mentioned peacocks for spending so much time on courtship and preening, but I rejected that one too.

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by Roslyn

Not when cupid strikes

Raphael's The Triumph of Galatea

“Not when cupid strikes.”

That was Christine Drea’s response at the Animal Behavior meeting last summer. She had just given a talk on her latest study, showing the dramatic effects of hormonal contraception on the way lemurs communicate with the opposite sex1. I was asking her what advice she gives to women about birth control. On the 50th anniversary of the Pill, scientists like Drea were adding to the evidence that we might want to think twice about our widespread use of these drugs. The lemur research suggests that hormonal contraception could be replacing one “problem that has no name” – Betty Friedan’s idea of the dissatisfaction felt by modern women – with another2.

Like many primates, ring-tailed lemurs have a complicated system of signaling to one another through scent. Males are able to detect the sex, fertility and even the identity of a particular female by smell alone3. At first glance, the connection to humans might seem far-fetched, since our noses are pretty poor compared to other mammals. But we are relatively well-endowed when it comes to scent production: humans have more scent glands on the surface of our skin than any other primate4.

We also have some surprising olfactory abilities lurking beneath the surface. The classic example is the T-shirt test. In the 1990s, researchers at the University of Bern in Switzerland gave a group of men T-shirts to take home, with instructions to sleep and sweat in them over the next two nights5. When women were later asked to sort the dirty T-shirts based on pleasantness of smell, they did something surprising. Their rankings came down to genes: the more genetically distinct a man was from a female rater, the more she liked his scent.

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by Roslyn

Backpedalling on backwards evolution

In a recent post I wrote about irreversible colour changes in morning glory flowers, and how this was promoted as evidence that evolution does not work in reverse1. This is called Dollo’s Law, after the 19th century Belgian paleontologist Louis Dollo. He spent most of his life digging up and reconstructing Iguanodons, but his name lives on in our concept of evolutionary trees. In linguistics, for example, the “stochastic Dollo” model refers to the scenario where words can only arise once in a family of languages2.

Louis Dollo supervising the reconstruction of an Iguanodon

Louis Dollo supervising the reconstruction of an Iguanodon. From Wikimedia Commons.

And the reason Dollo’s name is forever tied to the idea of history not repeating? He wrote that “an organism is unable to return, even partially, to a previous stage already realized in the ranks of its ancestors.”3

Frogs might prove Dollo wrong. A new study by John Wiens, a herpetologist at Stony Brook University, proves that a South American frog re-evolved the long lost bottom teeth of its ancestors, after going more than 200 million years without them4.

Guenther’s marsupial frog lives in the tropical forests of Colombia and Ecuador. It is the only frog we know of among thousands of species with true teeth in its lower jaw. Nearly all frogs have teeth, but only on the upper mandible. They use their single set for grasping prey items that they swallow whole, rather than chewing. The closest amphibian relatives to frogs, salamanders and worm-like caecilians, have maintained upper and lower teeth. This means that somewhere along the line, early frogs lost their bottom set.

As the odd one out, Guenther’s marsupial frog was originally placed in its own family within the taxonomic order Anura. But early studies of tadpole development and immunological proteins suggested that something was off5. In some ways, the marsupial frog was similar to typical tree frogs in the family Hylidae.

John Wiens’ latest results provide a more comprehensive picture of the early amphibian family tree than ever before. He compiled genetic data from 170 species of frogs, salamanders and caecilians. The new phylogeny firmly places Guenther’s marsupial frog in the family Hemiphractidae, and, by calibrating the new tree with evidence from the fossil record, Wiens can pin down the timing of events in amphibian history. His results show that frogs evolved from a salamander-like ancestor and lost their bottom teeth over 230 million years ago – and Guenther’s marsupial frog regained them quite recently, within the last 17 million years.

Hoatzin chick

The marsupial frog is just the latest in a long line of putative exceptions to Dollo’s Law. Others include fossil ammonites that have lost and regained the coiled form of their shells several times3, and modern slipper limpets that regained the coiled shells of their snail-like ancestors6. Some lizards have re-evolved long lost fingers and toes7. The strange bird known as the hoatzin, which has claws on its wings that are used for climbing until its wings are fully developed for flight, might have re-evolved this feature from its dinosaur ancestry. These examples have led some authors to argue that Dollo’s Law has outlived its usefulness8. Should it go the way of chewing teeth in hens and (most) frogs?

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by Roslyn

Wherefore the mustache?

Ears, palms, toes, neck, and nose. In that order.

These are the grossest places for humans to have hair, according to Queen’s students. Ok, there were a few others that I didn’t mention. The upper lip, however, did not receive a single vote.

Last fall a number of men in the biology department grew competitive mustaches for “Movember” prostate cancer research fundraising. This required mass beard shaving on the first of November. Martin Mallet, known for his thick coat of fur, emphatic hand gestures and all-around intensity, suddenly transformed into a meek imposter. For the first time Martin had no probing questions for the speaker at the EEB seminar. I can’t help but wonder: if he did, would anyone have noticed?

I started to recognize Martin again when the hair on his upper lip attained visibility. Other men of Movember fared less well. It can’t be a good thing when the people who work in the same office as you don’t even notice your new, mustachioed face.

But what, if anything, is it for? My experience suggests that human facial hair serves as a male status signal. Is this why we evolved mustaches in the first place?

Inca Tern

Why do mustaches evolve? Inca tern, from Wikimedia Commons.

In class the other week we discussed Stephen Jay Gould and the trouble with adaptationism. Gould famously criticized the proliferation of sloppy adaptive reasoning in his 1979 paper “The Spandrels of San Marco and the Panglossian Paradigm“1. He took aim at scientists who apply adaptive “story-telling” to nearly anything – from the colour of our skin to the size of our noses – in an unverifiable, unfalsifiable way.

It can be easy to jump on the adaptationist bandwagon, since these stories are often quite plausible. This may have been especially true when “Spandrels” was written, due to the rise of some revolutionary ideas about how to apply evolutionary biology to the study of social behaviour. There was plenty of new research to be done. Of course, many of the people doing this research disagreed with Gould’s characterization2. At its worst, adaptationist thinking might lead to some bad science, especially when it comes to human behaviour (where confounds are especially hard to control). But speculation is a necessary part of the scientific method, and adaptive reasoning can be a good place to start.

It is worth noting that Gould’s paper has been enormously influential. “Spandrels” has been cited well over 3500 times. I’m still waiting on citation number 3 for my Master’s research.

And yet, the response of the research community to the “Spandrels” critique has largely been, “That’s well said, but let’s get back to our field work.”2 In that spirit, consider the mustache. Can we speculate about it in a reasonable way, avoiding the big adaptationist pitfalls?

First of all, is this question worth asking?

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by Roslyn

Super indelible flower colours

How do you fire a pollinator?

That was the question in last week’s Ecology, Evolution and Behaviour departmental seminar. The speaker was James Thomson, an evolutionary ecologist from the University of Toronto who specializes in the interactions between plants and their animal pollinators. His research shows that nectar-addled hummingbirds are like corporate ladder climbers. Bees, on the other hand, are always getting canned.

Pollination syndromes have been a major focus of Thomson’s work1. These are not garden ailments. “Syndrome” here refers to a suite of traits that tend to be found together, in this case because they help a plant attract a certain kind of pollinator.

Bird-pollinated flowers tend to be red and tube-shaped, producing lots of nectar but relatively little scent. Birds have sharp vision, and do not depend much on their sense of smell. Honeysuckle is an example of this type of flower – or anything that looks like a hummingbird feeder. Bee-pollinated flowers come in shades of yellow, blue, and purple, because bees cannot see the colour red. Familiar examples are sunflowers, snapdragons and wild pansies. These often have petals modified into special bee landing platforms. Flowers that specialize on birds and bees are common, but there are many other pollination syndromes. If a flower is orange-brown and smells like rot, it probably depends on carrion flies. Mammal-pollinated flowers often smell fruity, like synthetic grape flavouring.

In his talk, James Thomson reviewed a decade’s worth of work on beardtongue flowers from the genus Penstemon2. In 2007, Thomson and his collaborators used genetic analyses to build the evolutionary tree for close to 200 of the species in this group3. When flower traits were mapped on to the Penstemon family tree, interesting patterns were revealed.

First, the bird and bee pollinated species were distributed broadly throughout, implying frequent transitions between these two syndromes in the history of the Penstemon group. Like an evolutionary magnet, pollination by one type of animal or another exerts a strong pull on multiple flower traits in concert. Evolving species are drawn rapidly towards a new form, so you almost never find intermediates.

This lability or changeable nature of floral traits was not much of a surprise, but the Penstemon tree also suggested something incredible. Floral evolution was directional.

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