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:
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.
My recent MSc student’s first paper is in press and published!
Wang, SYS, Tattersall, GJ, and Koprivnikar, J. 2019. Trematode parasite infection affects temperature selection in aquatic host snails. Physiological and Biochemical Zoology, 92(1):71–79.
Susan examined whether naturally occurring trematode parasite loads influenced snail (host) thermal preference and found that there was an approximately 2°C higher preferred temperature in parasitised snails compared to non-parasitised individuals.
But, one of the challenges with laboratory thermal preference experiments is that slow moving ectotherms can become “thermally trapped” in colder temperatures, and thus their null (in the absence of a preference) distribution needs to be assessed to compared to the observed distributions. So we employed some mathematical modelling to assist in determining the null distributions.
The code and explanation for the code can be found here on github:
Just returned from an interesting day of thermal imaging on topics ranging from birds to asphalt and with no particular connection other than the technological one. It was quite an interesting contrast, but the engineers, technicians, electricians, and thermographers seemed reasonably interested in our work. I am very grateful to the FLIR folk (Paul Frisk and Rob Milner) for inviting us to speak and especially grateful to Joshua Robertson and Erich Eberts, my “extended” family of research student collaborators for talking about our work.
Joshua spoke about his new results on stress physiology and the use of infrared thermal imaging and Erich spoke about his crowd-funded hummingbird research. They did an excellent job! Certainly well prepared for any upcoming conferences!
In a narcissistic age, it is not uncommon to think of situations in which spending too long focussed on ourselves can lead to harm. But what about fish, you might ask?
Today our paper entitled “Social cues can push amphibious fish to their thermal limits” was published in Biology Letters.
This manuscript represents an experimental field study performed in Belize this past spring examining how social information can delay the behavioural thresholds that an amphibious fish exhibits to escape from a thermally stressful environment. As natural environments are complex systems including abiotic and biotic stressors that may act synergistically, it is important to understand how these interactions operate and impact an animal’s thermal limits.
The mangrove rivulus (Kryptolebias marmoratus), in particular, is an intriguing fish since it routinely leaves the water (emerge) to avoid stressful conditions and in some instances can survive for weeks out of water. If the water gets too hot or too hypoxic, rivulus will simply jump out and chill out on land.
K. marmoratus contemplating life on land. Not quite sure yet. Photo courtesy Keri Martin, Mount Allison University.
K. marmoratus out of water – Image courtesy of Keri Martin, Mount Allison University.
In the present study, we demonstrate that the decision to emerge from water onto land is also socially sensitive.
So, what does this have to do with self-image? Studying social cues from conspecifics can be a challenge if the conspecifics jump out of water first, so we designed an experiment to provide continuous social cues, using a simple mirror placed underwater.
Supplementary Figure from manuscript
Key Finding: The presence of cues from a conspecific (produced from a mirror) caused the rivulus to delay leaving water until they reach a higher temperature. This delay is clearly a behavioural decision and not due to enhanced tolerance of warmer temperatures, since their CTmax was not sensitive to the presence of social cuing from the mirror.
This discovery is important since it demonstrates that critical behavioural decisions may affect survival in an animal living in a thermally stressful environment. Much research into thermal stress to date has focussed on individual responses but social cues are likely just as important to animals in the wild. We have only addressed what simple visual cues produced by a mirror do to their emersion behaviour. Extrapolating to how multiple cues will work is, of course, open for future investigation.
Full Citation:
Currie, S and Tattersall, GJ. 2018. Social cues can push amphibious fish to their thermal limits. Biology Letters. Link here
Further Information
K. marmoratus inhabit stress aquatic habitats and can be found often inside crab burrows.
See Dr. Andy Turko’s video from 2012. It is fascinating to watch:
On this year’s trip we took more images attempting to visualise the thermal environments inhabited by the various fish living in the Long Caye. Here is a thermal image of a crab burrow:
Thermal image of a crab burrow (central triangular region) capturing a crab leaving the burrow (bottom centre of image). Rivulus can be found cohabiting with crabs or each other. Image taken in April 2018 with a FLIR T1030K thermal imaging camera.
Ever hopeful to observe rivulus emerging spontaneously in the field we set up various camera traps and go pros and time lapse images.
The following video depicts a time lapse video (each frame 10 apart) captured with a simple IR webcam of a outdoor, artificial burrow with water, following 3 rivulus over time. You can see one emerging in the bottom part of the screen and staying out of water.
We want to acknowledge Team Rivulus and Fellow Scientists:
Seriously, though, I’ve just been invited by Professor Heldmaier to be a member of the Journal of Comparative Physiology B editorial board. I am honoured! More especially as one my earliest memories of an influential paper was Heldmaier and Ruf’s 1992 paper on “Body temperature and metabolic rate during natural hypothermia in endotherms” published in J Comp Physiol B. Their paper really helped to spark my interest in hibernation and thermoregulation as it so elegantly explained concepts that can trip up any novice student of physiology. Anyhow, it is an honour to be part of Dr. Heldmaier’s team.
So, now, I put out a call to anyone reading this post to consider submitting their comparative physiology research to J Comp Physiol B for consideration.
One of the pleasures of academia is the “seminar invite”. I just returned from a visit to the University of Pittsburgh Pyamunting Laboratory of Ecology. Only a 3 hour drive from my house:
Many thanks to Dr. Corinne Zawacki for the invitation and for hosting me and showing me around the field station. This truly is an impressive place for doing field research. Hopefully we can collaborate in the future.
Thanks also to my supportive grad students (who put up with disappearances) and the unwitting co-authors (Ray Danner, Jaime Chaves, Danielle Levesque). I was speaking about our research on Darwin’s finches….
I’ve often thought that I wait too long to post anything about research until it has been completed. However, in this case I make an exception. We were able to get our flight mill working today with a male carpenter bee! Video evidence below:
Full credit to the two fantastic high school mentorship students (Hailin Wang and Sam Langdon) who built the flight mill with the assistance of Brock University’s Electronic’s Shop and Machine Shop, and to Miriam Richards, my colleague in all matters related to bees.
Now, we simply have to put the final touches and hopefully Lyndon Duff (Miriam’s PhD student) will be flying bees this summer.
