Hot-headed squirrels use eye fat!

Our paper has just been published, this one a collaboration led by Amanda MacCannell from Dr. James Staples lab at Western University.

Here’s a summary (cribbed from the abstract):

We discovered an orbital lipid depot in the 13-lined ground squirrel during the first ever magnetic resonance image (MRI) of this common experimental model of mammalian hibernation. The volume of this depot increased in the autumn and decreased in the spring, suggesting an endogenous circannual pattern. Water-fat MRI revealed that throughout the year this depot is composed of ∼40% lipid, similar to brown adipose tissue (BAT). During arousal from torpor, thermal images showed higher surface temperatures near this depot before the rest of the head warmed, suggesting a thermoregulatory function. This depot, however, does not contain uncoupling protein 1, a BAT biomarker, or uncoupling protein 3. Histology shows blood vessels in close proximity to each other, suggesting it may serve as a vascular rete, perhaps to preferentially warm the eye and brain during arousals.

And a link to the paper:

http://jeb.biologists.org/content/early/2019/01/23/jeb.195750

Thermal video time lapse of a 13-Lined ground squirrel arousing from hibernation. Note the warm region behind the eye (1990 s) corresponding to the orbital lipid depot. Warm surface temperatures provide hints toward changes in relative blood flow and metabolism in the underlying tissue during the rapid rise in body temperature from 5 to 37C.

Reprint requests can be sent to umamac@leeds.ac.uk.

Citation:

MacCannell, ADV,  Sinclair, KJ, Tattersall, GJ, McKenzie, CA, and Staples, JF. 2019. Identification of a lipid-rich depot in the orbital cavity of the thirteen-lined ground squirrel. Journal of Experimental Biology, 222: jeb195750 doi: 10.1242/jeb.195750

One thing I found really interesting about this was the fact that brain temperatures are kept warmer than body temperature, something I noticed back in 2009 studying Columbian ground squirrels (something also noted by Heller in his seminal work in the 1970s). At the time, I assumed this was related to higher metabolic heat production of the brain, and yet we observed rapid transient changes in hypothalamic temperature during hypoxic transitions that might readily have been explained by changes in blood flow. Further study in other hibernators seems to be required to corroborate Amanda’s neat findings!

From Tattersall and Milsom, 2009 J Physiol 587: 5259–5274

For a nice JEB write-up that succinctly summarises the study better than I can, please see Kathryn Knight’s article here:

http://jeb.biologists.org/content/222/4/jeb201228

 

Lizard Chapter Published

A book on the “Behavior of Lizards: Evolutionary and Mechanistic Perspectives” (Eds. Vincent Bels and Anthony Russell) has just been published with a chapter from my lab!

https://www.crcpress.com/Behavior-of-Lizards-Evolutionary-and-Mechanistic-Perspectives/Bels-Russell/p/book/9781498782722

Chapter 1: Behavioral thermoregulation in lizards: Strategies for achieving preferred temperature – Ian R.G. Black, Jacob M. Berman, Viviana Cadena, and Glenn J. Tattersall

This work was primarily the result of collaborative work of my former graduate students, Ian Black, Jacob Berman and Viviana Cadena. I am very grateful to have great graduate students willing to work on these projects.

If you are interested in accessing this chapter, contact me by email or on researchgate.

Poetry of Cassowary Casques

So, we published a paper on Cassowary Casques the other day, and then we heard from a Science Communications person that he had written a poem inspired by our research!

http://thepoetryofscience.scienceblog.com/760/the-curious-case-of-the-cassowary-casque

How cool is that!?

The study itself was conducted by Danielle Eastick of La Trobe University (Dr. Kylie Robert and Dr. John Lesku), and published in Scientific Reports recently. Here is a link to the paper.

I won’t link to all the overhyped media reports since they tend to misinterpret (e.g., no, we have not discovered the secret to the casque) the science just like they misinterpreted our toucan bill study.

But here are the main results:

One of the most beautiful and dangerous animals around!

Abney Defends MSc

Congratulations to Curtis Abney, MSc for his successful defence today! His thesis on “Thermal ecology of eastern garter snakes in a southern Ontario peatland” was a joy to supervise, namely because Curtis did all the hard work. Always enthusiastic and willing to wade through tick-infested field sites, Curtis studied whether garter snakes make use of thermal cues to inform site selection in the field.

Thanks of course to Curtis’ committee members: Dr. Cheryl McCormick, Dr. Miriam Richards, Dr. Liette Vasseur and Dr. Njall Rollinson (External examiner from U of Toronto).

Curtis will be missed by all members of the lab as he moves back to BC aand takes the next big step in his scientific life.

Learning from Tortoises

Our paper on red-footed tortoise reversal learning is now in press! This study represents the efforts of Justin Bridgeman during his honours thesis examining behaviour flexibility and cognition in tortoises. Here is a link to the paper:

https://rdcu.be/bjHU7

Bridgeman, JM and Tattersall, GJ. 2019. Tortoises develop and overcome position biases in a reversal learning task. Animal Cognition. (): 1-11. 10.1007/s10071-019-01243-8

Many thanks to Dr. Miriam Richards, TAs, Tom Eles, and all the students from our animal behaviour course (2013 – 2015) who helped with all the pre-training and Y-maze familiarisation trials that pre-dated Justin’s honours research. And many thanks to all the tortoises who participated.

Tortoise approaching the stimulus (mock experiment with cell phone video)

Tortoise receiving a reward for approaching the correct stimulus.

Here are some sample videos from the supplementary material:

Tortoise in the Y-maze examines both stimuli and slowly approaches the rewarded stimulus on the left.

Tortoise late in the training approaches the rewarded stimulus without pause.

Tortoise moves according to its developed position bias, almost makes an error but corrects itself, and approaches the positive stimulus receiving the reward.