Tuesday, October 24, 2017

The Smell of Fear

A reposting of an article from October 24, 2012.

Several animals, many of them insects, crustaceans and fish, can smell when their fellow peers are scared. A kind of superpower for superwimps, this is an especially useful ability for prey species. An animal that can smell that its neighbor is scared is more likely to be able to avoid predators it hasn’t detected yet.

Who can smell when you're scared? Photo provided by Freedigitalphotos.net.
“What does fear smell like?” you ask. Pee, of course.

I mean, that has to be the answer, right? It only makes sense that the smell of someone who has had the piss scared out of them is, well… piss. But do animals use that as a cue that a predator may be lurking?

Canadian researchers Grant Brown, Christopher Jackson, Patrick Malka, Élisa Jaques, and Marc-Andre Couturier at Concordia University set out to test whether prey fish species use urea, a component of fish pee, as a warning signal.

A convict cichlid in wide-eyed
terror... Okay, fine. They're
always wide-eyed. Photo by
Dean Pemberton at Wikimedia.
First, the researchers tested the responses of convict cichlids and rainbow trout, two freshwater prey fish species, to water from tanks of fish that had been spooked by a fake predator model and to water from tanks of fish that were calm and relaxed. They found that when these fish were exposed to water from spooked fish, they behaved as if they were spooked too (they stopped feeding and moving). But when they were exposed to water from relaxed fish, they fed and moved around normally. Something in the water that the spooked fish were in was making the new fish act scared!

To find out if the fish may be responding to urea, they put one of three different concentrations of urea or just plain water into the tanks of cichlids and trout. The cichlids responded to all three doses of urea, but not the plain water, with a fear response (they stopped feeding and moving again). The trout acted fearfully when the two highest doses of urea, but not the lowest urea dose or plain water, were put in their tank. Urea seems to send a smelly signal to these prey fish to “Sit tight – Something scary this way comes”. And the more urea in the water, the scarier!

But wait a minute: Does this mean that every time a fish takes a wiz, all his buddies run and hide? That would be ridiculous. Not only do freshwater fish pee a LOT, many are also regularly releasing urea through their gills (I know, gross, right? But not nearly as gross as the fact that many cigarette companies add urea to cigarettes to add flavor).

The researchers figured that background levels of urea in the water are inevitable and should reduce fishes fear responses to urea. They put cichlids and trout in tanks with water that either had a low level of urea, a high level of urea, or no urea at all. Then they waited 30 minutes, which was enough time for the fish to calm down, move around and eat normally. Then they added an additional pulse of water, a medium dose of urea, or a high dose of urea. Generally, the more urea the fish were exposed to for the 30 minute period, the less responsive they were to the pulse of urea. Just like the scientists predicted.

A rainbow trout smells its surroundings.
Photo at Wikimedia taken by Ken Hammond at the USDA.

But we still don’t know exactly what this means. Maybe the initial dose of urea makes the fish hide at first, but later realize that there was no predator and decide to eat. Then the second pulse of urea may be seen by the fish as “crying wolf”. Alternatively, maybe the presence of urea already in the water masks the fishes’ ability to detect the second urea pulse. Or maybe both explanations are true.

Urea, which is only a small component of freshwater fish urine, is not the whole story. Urea and possibly stress hormones make up what scientists refer to as disturbance cues. Steroid hormones that are involved in stress and sexual behaviors play a role in sending smelly signals in a number of species, so it makes sense that stress hormones may be part of this fearful fish smell. But fish also rely on damage-released alarm cues and the odor of their predators to know that a predator may be near. Scientists are just starting to get a whiff of what makes up the smell of fear.

Want to know more? Check these out:

1. Brown, G.E., Jackson, C.D., Malka, P.H., Jacques, É., & Couturier, M-A. (2012). Disturbance cues in freshwater prey fishes: Does urea function as an ‘early warning cue’ in juvenile convict cichlids and rainbow trout? Current Zoology, 58 (2), 250-259

2. Chivers, D.P., Brown, G.E. & Ferrari, M.C.O. (2012). Evolution of fish alarm substances. In: Chemical Ecology in Aquatic Systems. C. Brömark and L.-A. Hansson (eds). pp 127-139. Oxford University Press, Oxford.

3. Brown, G.E., Ferrari, M.C.O. & Chivers, D.P. (2011). Learning about danger: chemical alarm cues and threat-sensitive assessment of predation risk by fishes. In: Fish Cognition and Behaviour, 2nd ed. C. Brown, K.N. Laland and J. Krause (eds). pp. 59-80, Blackwell, London. 3.

Tuesday, October 17, 2017

Caught in My Web: Animals of the California Fires

Image by Luc Viatour at Wikimedia Commons
The current California wildfires have been rapidly destroying livelihoods, lifestyles and lives. The damage is horrific and recovery will take time, effort, and lots of support. When fires of this magnitude happen, what happens with our animal friends? We explore this with this edition of Caught in My Web.

1. Sarah Zielinski from National Geographic wrote a very informative article about how wildfires affect wild animals.

2. But while wild animals often have the freedom and abilities to escape the worst effects of fire, those protected in sanctuaries generally do not and have to evacuate.

3. Domesticated farm animals also need to seek refuge, and meeting the needs for large numbers of large animals can be a challenge.

4. Many people have been forced to flee so quickly that they lost contact with their beloved pets. But here is a heartwarming story of two brothers that returned to find their home destroyed and their beloved dog, Izzy, wagging her tail from the rubble.

5. But life does not pause when disaster strikes. Amid the wildfires, the Santa Rosa Wildlife Preserve welcomed the addition of a new baby Nile lechwe (an endangered species of antelope), who is healthy and strong. Their press release states, "It is easy to focus on the darkness in times of trouble but hopefully, stories like ours of a baby born in the midst of disaster, will remind us to see the light".

Do you want to do something to help the animals affected by the California fires? Here is how.

Tuesday, October 10, 2017

How To Get Into An Animal Behavior Graduate Program: An Outline

Do you dream about a career of studying animals?
Image by freedigitalphotos.net.
A reposting of an article from March 13, 2013.

**NOTE: Although this advice is written for those interested in applying to graduate programs in animal behavior, it applies to most programs in the sciences.**

So you want to go to grad school to study animal behavior… Well join the club! It is a competitive world out there and this is an increasingly competitive field. But if every fiber of your being knows this is the path for you, then there is a way for you to follow that path. With hard work, dedication and persistence, you can join the ranks of today's animal biologists to pursue a career of trekking to wild places to study animals in their native habitats, testing questions about the physiology of behavior in a lab, or exploring the genetics of behavioral adaptation.

This is an outline of advice on how to get into a graduate program in animal behavior. More details on the individual steps will follow, so leave a comment below or e-mail me if you have any particular questions you would like me to address or if you have any advice you would like to share.

  1. Get good grades, particularly in your science and math courses. And make sure you take all the science and math prerequisites for biology graduate programs.
  2. Prepare well for the GREs.
  3. Get research experience. This can come in many forms (such as volunteering in a lab, working as a field technician, or doing an independent project for credit), but as a general rule, the more involved you are in a project, the more it will impress those making acceptance decisions.
  4. Choose the labs you are interested in, not just the schools. As a graduate student, you will spend most of your time working with your advisor and the other members of your advisor’s lab. This means that the right fit is imperative. Figure out what researchers you may want to work with, then see if they are at a school you would like to attend.
  5. Be organized in your application process. There will be a lot of details to keep straight: due dates, recommendation letters, essays, communication with potential advisors… The more organized you are, the less likely you are to miss a deadline or make an embarrassing mistake.
  6. Write compelling essays. Most schools will ask you to write two short essays: a Statement of Purpose and a Personal History. This is your place to set yourself apart. They need to convey your experience with animal behavior research and passion for working with that particular advisor. They also need to be very well written, so expect to write multiple drafts.
  7. Be organized and prepared when you ask for your recommendation letters. The easier you make it for your references to write a thoughtful recommendation letter for you, the better the letters will be.
  8. Apply for funding. This isn’t essential: Most first-year graduate students do not have their own funding. But the ability of a school and a specific researcher to accept a graduate student depends on what funding is available to support them. If you have your own funding, it is more likely you will to be able to write your own ticket.
  9. Be prepared for each interview you are invited to.
  10. If at first you don’t succeed, try and try again. Although heartbraking at the time, it is very common in animal behavior graduate programs to not be accepted anywhere in your first year of applications. If you are rejected, it doesn’t necessarily mean you are not a good candidate. Often it means there is no funding available to support you in the labs you would like to join. Spend the year participating in research and applying for funding so you can reapply next year.
The submission of a successful application takes a lot of planning and preparation. Getting good grades is a continuous effort. Plus, the most successful applicants often have two or more years of research experience. Ideally, you are working on these two things at least by your sophomore year of college. But if you waited too long and you haven’t taken enough science or math prerequisites, your grades are not where they need to be, or you don’t have enough research experience, you can take some extra time after you graduate to take community college courses and volunteer or work in a lab. Persistence and dedication are key to following a challenging path.

Tuesday, October 3, 2017

Mind-Manipulating Slave-Making Ants!

A reposting of an article from October 10, 2012.

An entire colony enslaved by an alien species to care for their young. Slave rebellions quelled by mind manipulation. It sounds like science fiction, right? But it really happens!

Myrmoxenus ravouxi (called M. ravouxi for “short”) is a slave-making ant species in which the queen probably wears a chemical mask, matching the scent of a host species in order to invade their nest without detection. Once inside, she lays her eggs for the host species workers to care for. Armies of M. ravouxi workers then raid these host colonies to steel their brood to become future slave-laborers to serve the needs of the M. ravouxi colony.

A M. ravouxi queen throttling a host queen. Photo by Olivier Delattre.

Enslaved worker ants could rebel: They could destroy the parasite brood or at least not do a good job caring for them. But to selectively harm the parasite brood without harming their own nests’ brood, the host ants would have to be able to tell them apart. Ants learn the smell of their colony in their youth, so any ants born to an already-parasitized colony would likely not be able to tell apart parasite ants from their own species. But what about ants that were born to colonies before they were invaded?

Olivier Delattre, Nicolas Châline, Stéphane Chameron, Emmanuel Lecoutey, and Pierre Jaisson from the Laboratory of Experimental Ethology in France figured that compared to ant species that were never hosts to M. ravouxi colonies, ant species that were commonly hosts of M. ravouxi colonies would be better able to discriminate their own species’ brood from M. ravouxi brood. Host species may even be better at discriminating in general.

The researchers collected ant colonies from near Fontainebleau and Montpellier in France. They collected M. ravouxi colonies and colonies of a species that they commonly parasitize (but were not parasitized at the time): Temnothorax unifasciatus (called T. unifasciatus for “short”). The researchers also collected T. unifasciatus that were parasitized by M. ravouxi at the time. Additionally, they collected colonies of T. nylanderi and T. parvulus, two species that are never parasitized by M. ravouxi. (Sorry guys. All these species go by their scientific names. But really, that just makes them sound all the more mysterious, right?). The researchers took all their ant colonies back to the lab and housed them in specialized plastic boxes (i.e. scientific ant-farms).

On the day of the tests, the scientists removed a single pupa (kind of like an ant-toddler) from one nest and placed it into a different nest of the same species or back in its own nest. They did this for colonies of both non-host species and for colonies of host species T. unifasciatus that were not parasitized at the time. Then they counted how many times the workers bit the pupa (an aggressive behavior) or groomed the pupa (a caring behavior).

Workers from all three species bit the pupa that was not from their colony more than they bit their own colony’s pupa. But the T. unifasciatus (the host species) were even more aggressive to foreign pupa than the other species. And only the T. unifasciatus withheld grooming from the pupa that was not from their colony compared to the one that was from their colony. Although all three species seemed to be able to tell the difference between a pupa from their own nest versus one from another nest, only the species that is regularly enslaved by M. ravouxi decreased care to foreign young. So that is what these ants do when they are not enslaved. How do you think enslaved ants respond to their own species’ young compared to M. ravouxi young?

A 1975 cover of Galaxie/Bis, a French science
fiction magazine, by Philippe Legendre-Kvater.
Image from Wikimedia.
The researchers repeated the study using enslaved T. unifasciatus, placing either a pupa of their own species from a different nest or a M. ravouxi pupa in with their brood. Even though prior to M. ravouxi takeover the T. unifasciatus bit foreign pupa more than their own, after M. ravouxi takeover they didn’t bite foreign pupa of their own species or M. ravouxi pupa very much. Not only that, but they groomed the M. ravouxi pupa more than the pupa of their own species! Ah hah! Mind control!

This, my friends, is the kind of truth that science fiction is made from.

But how might this work? Ants born to an enslaved colony would be exposed to both their own odors and the M. ravouxi odors. Because ants learn the smell of their colony in the first few days after they emerge from their eggs, these enslaved ants would have a broader set of smells that they may perceive as being “within the family”. That would explain why the enslaved T. unifasciatus ants didn’t attack either the foreign-born T. unifasciatus or the M. ravouxi young, but it doesn’t explain why the enslaved ants provided more care to the M. ravouxi than they did to their own species. One possibility is that the M. ravouxi produce more or especially attractive odors to encourage the host workers to take care of them.

There is still more to learn about this system: How exactly may the M. ravouxi be hijacking the pheromonal systems of their host species? How are the host species protecting themselves from exploitation? I guess we’ll have to wait for the sequel.

Want to know more? Check this out:

Delattre, O., Chȃline, N., Chameron, S., Lecoutey, E., & Jaisson, P. (2012). Social parasite pressure affects brood discrimination of host species in Temnothorax ants Animal Behaviour, 84, 445-450 DOI: 10.1016/j.anbehav.2012.05.020