Highly stressed marmots are less likely to survive hibernation

Another marmot paper is out!

Wey TW, Lin L*, Patton ML, and Blumstein DT. 2015. Stress hormone metabolites predict overwinter survival in yellow-bellied marmots. acta ethologica, 18:181-185. doi: 10.1007/s10211-014-0204-6.

This has been out online for a while at: http://link.springer.com/article/10.1007/s10211-014-0204-6

But it just got included in a final paginated print volume.

Here's a quick summary:

There’s quite a lot of information in scat, aka animal feces—yes, poop. One kind of data that can be extracted is how stressed out an animal is. Animal’s produce more stress hormones in response to stressors, stimuli which could range from the threat of a predator to exercise. These hormones are eventually broken down and passed out of the body sometime later in feces. A normal stress response helps animals respond to their environment, but chronic stress can have negative health effects. (Sound familiar? It applies to people, too, of course.) For yellow-bellied marmots, getting ready for hibernation is a huge deal, and in a recent study , we found that the marmots that with very high levels of stress hormone by-products in their feces were less likely to survive the winter. This was true independent of their body weight, but the effect was bigger for skinner marmots, which suggests that being skinny and stressed out is an especially bad combination.

Read on for a more detailed description of the work...

 

Chronic stress can have negative health effects in humans and other animals, and methods to measure stress and its health impacts in wildlife are necessary for research and management. In particular, we want to find non-invasive measures that cause as little harm and stress to animals as possible. Glucocorticoid metabolites (the by-products of stress hormones) excreted in feces reflect the amount of stress hormones produced, and by proxy, the amount of stress response that animal had. Collecting feces is easy and, importantly, does not require drawing blood or other procedures that cause further stress to the animals. Measuring stress this way is, thus, a promising tool for wildlife studies, and in several species, higher levels of these fecal glucocorticoid metabolites (FGMs) are linked with reduced survival in populations of wild animals. (But, in other species, there is no evidence for this link.)

Yellow-bellied marmots require a lot of energy to hibernate successfully and survive the winter, and a previous study (Smith et al. 2012) confirmed that stressful stimuli resulted in higher levels of FGMs. Therefore, we hypothesized that marmots with the highest levels of FGM levels might be chronically stressed and the most likely to die during winter hibernation. We found that high FGM levels, both those measured over a long time (several months) or only in a short time (two weeks) right before hibernation, predicted lower chances of surviving the winter, as we expected. We also found that FGM levels were a stronger predictor of survival in skinnier marmots. This supports the idea that marmots with high levels of stress hormones are more likely to die during hibernation and that a combination of higher stress and low body weight is especially bad. Measuring stress hormone by-products this way therefore seems like one useful indicator of potential poor health in marmots, and our study adds to a more general understanding of the links between stress and health in wild animals.

Meet Tiffany

Hi everyone!

I'm Tiffany Armenta, a new-ish graduate student in the Blumstein lab.

I've been at RMBL since mid-April and absolutely love it here. I've done fieldwork in the past but have never been at a field site for such a long time, so this has allowed me to become completely immersed in my work. Plus, the hiking and biking opportunities around here are exceptional :)

In addition to the standard observations and samples we collect when trapping, I am stabilizing RNA from the marmots in order to look at genes expressed in their blood. I aim to compare the expression profiles of different phenotypes in order to see how environmental conditions can affect the genetics of individuals and, in turn, how these profiles may alter an animal's physiology.

For instance, I think it will be interesting to compare marmots that consistently exhibit signs of high vs. low stress (based on behavioral and physiological data). Studies of other (mostly model) organisms show over-expression of anti-inflammatory genes and under-expression of anti-viral genes in stressed individuals so it will be interesting to see if these patterns persist in a natural population.

I am also interested in the underlying mechanisms that occur when an individual prepares to disperse, so I focused on collecting RNA from our yearling marmots this summer. These guys will likely be exposed to new pathogens during this journey and will travel much further than they ever have in their entire life, so I expect dispersers to show a different pattern when it comes to metabolic and immunological genes.

In order to do this, I have to first build the marmot transcriptome, which is basically just the transcribed regions of the species' genome. This may not look like anything special, but it took me months of quality control and program queries to get this figure, which shows RNA sequence data that aligns to the 13-lined ground squirrel genome.

 

The lowest window here represents the squirrel genomic sequence: exons are blue blocks and introns are the lines with arrowheads. The large middle window displays marmot sequence (from one individual) that aligns to the squirrel genome, with each line representing a unique expression of that sequence.

Note that the majority of the marmot sequences (small gray squares) align with the squirrel exons. This was the highlight of my week because RNA should only be exonic sequences, so this means I've done something right! Success!

The next step is to identify the genes being expressed based on homology in other organisms (such as the squirrel and mouse) and then to quantify expression values. So expect to hear more from me once I make another breakthrough...

UCLA Science Poster Day 2012!

Today was poster day, and boy did these posters look great! 

The undergraduates in our lab explained their exciting 

new discoveries to the broader UCLA community.

Rachel Stafford-Lewis: 

Proximate mechanisms mediating life history trade-offs in 

facultatively social yellow-bellied marmots

Kathy Nguyen: 

Yellow-bellied marmot call structure is heritable

Lawrance Chung: 

Ontogeny of social partner choice in free-living yellow-bellied marmots

  

Connie Lin: 

Does serotonin modulate social interactions in hermit crabs?

And, last but not least, the "killer" title,

"The Omnivore's dilemma: diet explains variation in roadkill mortality"

By Taylor Cook

There were also members from Barney Schlinger's lab presenting on their research on hormones and genetics in song birds. 

Lots of good questions were asked and new insights were gained...

 

 

Lawrance's poster provoked a lot of positive (affiliative) 

social interactions within his social group...

 But, alas, all good things must come to an end and the poster's came down. Luckily, the Department of Ecology & Evolutionary Biology will have its own showing of these posters tomorrow, so be sure to stop by the Fifteenth Annual Biology Research Symposium - Wednesday, May 16, 2012, at 1:00 - 4:00PM at the UCLA Faculty Center...See you there!

Scared and Less Noisy

Have you ever heard a marmot's alarm call? I have! It's a distinctive, high-pitched, whistle-like sound that could be clear and piercing, or pretty noisy.

Marmots alarm call when they get scared, be it from predators trying to eat them...

...or from marmoteers trying to bag them (to take their measurements).

The question is - whether the marmot alarm call, this sound of fear, can be a quantitative measurement of just how scared these marmots are. This is what my past year's research is all about. To read the recently published article on this topic by Dan and me, you may have to purchase access to Biology Letters here. For the short, free version, just read on.

Dan and I hypothesized that marmots would produce clearer alarm calls when they are less scared and noisier calls when they are more scared. We used a measure of noise known as Wiener entropy to quantify the noise within the calls. To quantify fear, we measured the glucocorticoid levels found in marmot fecal samples, with higher glucocorticoids indicating greater fear.

We then extracted seven years' worth of data on marmot alarm calls and their associated fecal samples recorded and collected, respectively, in RMBL. These data were compiled by the marmoteers during the summers of 2003 thru 2009; when the marmots called, they recorded them; when the marmots pooped, they picked up after them, and sometimes quite literally, wiped their butts. (Thanks for all the hard work, guys!)

After repeated analyses controlling for all the variables we could think of, including but definitely not limited to sex, mass, age, background noise, and call harmonics, we got the same surprising result - the marmots are generating clearer, less noisy alarm calls when they are more scared.

A couple days' worth of head-scratching later, Dan and I decided that our surprising result makes sense after all. Positive correlations between heightened stress and clearer calls have also been demonstrated in piglets, dwarf goats, and dogs. Of course, formal experiments will have to be conducted to show a causal relationship between fear and the clarity of alarm calls.

In a more intensely fear-induced state, the marmots' vocal folds are pulled more taut, effecting clearer, more piercing calls. The clarity of the call can, in turn, ensure that marmots in the area who hear the call would clearly receive the message. As such, the fear-induced clarity in alarm calls could be selected for within marmot colonies.

Try putting yourself in the situation of a scared marmot. Are your calls likely to be more or less sharp and clear if you experience a heightened state of fear?

Marmot days of summer

July is here and it is officially summer at RMBL.


Most of the snow has melted from the mountains and this water is helping to turn the landscape green.


The vegetation is now growing, waterfalls are rushing, and flowers are blooming.



Marmots enjoy the benefits of this extra cover because it provides them with new opportunities to forage.


They also use tall vegetation, such that shown below, to seek protection when faced with predation risk.


Of course, because this extra food brings multiple marmots out of their burrows to forage at once, marmots are also spending much of their active time socializing with their group-mates.


We paint a unique dye mark on the back of each marmot to keep track of which animal is which. For example, you can see "Y" is the adult female on the rock in the middle of the photo below.


Team marmot is now busy recording social behavior and trapping marmots from our study population. However, not all of the marmots are easily convinced that they should go inside of our traps!


Luckily, for Team Marmot, our days in the mountains are long, so we can take full advantage of this active time to collect data and spend many hours surrounded by beautiful scenery. Yes, the life of a marmoteer is certainly rough these days.

50 Years of Marmot Research!!!

Building upon the pioneering efforts of Ken Armitage and the efforts of numerous marmoteers over the years, Dan Blumstein now oversees the marmot research project. As a result of these collaborative efforts, this project has been going for half of a century now.


Most projects only last for 3-4 years (the duration of a dissertation or granting period), so this is quite an accomplishment. To celebrate our golden anniversary, Dan made T-shirts! Check out the logo below:


And the current crew in the field wearing our shirts with pride!

Here's to another 50 years of new discoveries...and FUN!!!

Individuality in Rodents: Research in the News

Being part of the crowd is what makes you unique. Say what?...

That’s the bottom line of a multi-year study I did with Dan as part of my dissertation research. We looked at eight different species of social ground-dwelling rodents, including marmots and their close cousins prairie dogs and ground squirrels. We found that as social group size increases over evolutionary time, so does the degree of individuality in the animals’ voices. Our study is the cover feature of the latest issue of Current Biology.

Pollard, KA & Blumstein, DT. 2011. Social group size predicts the evolution of individuality. Current Biology 21(5): 413-417. doi 10.1016/j.cub.2011.01.051 Available here.

Our study has been covered in popular press outlets, including:

Discover

NPR

Discovery News

The Daily Mail UK

Ars Technica

Science Daily

The Varsity

EurekAlert!

and more!

Mom and dad: A story of hair

When studying evolution, it is primordial to know the relatedness of the different individuals in a population. All least, we need to know who is the father and the mother of the different offspring we see every summer. Why it is so important? Simply because if you see a difference between the parents and their offspring and if this difference it due to genes then you are looking at evolution.

Marmot pups are really cute when they emerged from their burrow. Every year we asked them who are their mum and dad. However, no pups ever answered our questions. We tried to convince them to give us a nice drawing of their mum and dad, but we badly failed. Most of the time, when we approach they simply alarm-call or ignore us. One good thing for us is that when pups emerge from their burrow, they still hang-out most of the time with their mother and their brothers and sisters. By observing them, we are confident about who their mother is.

Telling who is the father is a totally different story. As in most animals, marmot males do not care about their offspring. After copulation, their main activity is getting big, fat, round, and plump. Males do not provide cares to the offspring. So observations could in no way give us information about paternity. Worth that than during the mating period, females copulate with different males, and in a same litter, pups could have different fathers. So to the different fathers of the pups, we are asking the question directly to the pups. Not truly to the pups, we asked the question to their hairs. Hairs provide all the information we need. Using some hair torturing techniques, also called molecular techniques, involving alcohol,burning and heating, we could extract DNA. With this DNA, we genotype the pups and by comparison with the genotype of the potential fathers, we could determine who is the father of whom. Basically, for a geneticist or a molecular biologist, hairs (or others samples with DNA) are really equivalent to the little paw-written pedigree we could ask to the pups. However, 'reading' the pedigree in hairs is more complex and need a large amount of work in the lab.

Maternity has been determined based on behavioral observations since 1962, and paternity was assigned using molecular techniques since 2000. The entire pedigree in the marmot population have 3500 individuals. We know the mother of 90% of the individuals since 1972 and we know 84% of the fathers since 2000.

This is a graphical representation of the marmot pedigree at RMBL. Each point represent an individual. Red lines stand for maternal link and blue one for paternal ones. To clarify the pedigree, I have made two graphs: one for the mums


and one for the dads




Below is a graphic of one of the longest patriline observed in our population (72 descendants over 5 generations). Squares are males and circles are females.

News Story on Hyenas Greeting their "Friends": Who do Marmots Greet?

Photo by Kay E. Holekamp

You might be wondering what the photo above (of two adult female hyenas greeting each other) is doing on a blog about marmots. Please let me explain...

In my doctoral research, with Dr. Kay Holekamp at Michigan State University, I studied spotted hyenas. Our new paper on the subject is now in press at Animal Behaviour and will be officially published in February.

This research was just covered by reporter Victoria Gill at BBC News Earth in her story entitled, "Hyenas 'greet friends' to ask for their help". Check out this news story, and other news coverage below:

BBC News Story

Daily Nation Story,
"The female hyena calls the shots"

Other coverage:
Sify News
Thaindian News
Newstrack India
MSU Research News
WorldNews
Herald Globe
Leadership
Nigerian Best Forum
Top News

The original paper article, "Greetings promote cooperation and reinforce social bonds among spotted hyaenas" is in press at Animal Behaviour (doi:10.1016/j.anbehav.2010.11.007)

Visit my website to learn more about studies on cooperation and to see videos of hyenas greeting!

Greeting confirm social bonds among "friends", especially among genetic relatives, before hyenas engage in risky cooperative behaviors such as attacking lions (see below).



As part of "Team Marmot", I am now investigating how greetings structure affiliation networks among yellow-bellied marmots. Although marmot greetings take-on quite a different physical form, I am asking how greetings function to structure marmot social networks.

Tina Wey and others from our lab recently showed that marmots, like spotted hyenas, tend to greet their kin in affiliation networks more often than they greet non-kin. My work on maternal effects will extend this finding. It will be interesting to learn whether convergent selection pressures also favor greetings among genetic relatives in marmots.