The experiment has begun, and so the time has come to explain what it is exactly that I am attempting to accomplish over the course of the next two semesters. I have already stated my three hypotheses in a previous blog post, but here they are again… just in case they’ve slipped your mind!
Hypothesis 1: I Hypothesize that the visual modality is involved in conspecific interactions between pairs of red-backed salamanders and that it interacts with the olfactory modality.
Hypothesis 2: I hypothesize that olfactory cues or the visual cues contain information about the sexual identity of the competitor.
Hypothesis 3: I hypothesize that colour vision plays a role in salamander conspecific interactions.
In order to support or disprove my hypotheses, I have come up with three experiments. This week, I started the first experiment, which addresses my first hypothesis. It is a cue isolation experiment, in which 40 salamanders (20 mature males and 20 juveniles) will undergo 4 separate treatments:
Treatment 1 (OV): In this treatment the salamander will be confronted with a male olfactory cue (O), in the form of the moist paper towel lining the cage of another male salamander, and a male visual cue (V) in the form of a video I made of a male salamander.
Treatment 2 (OC):This treatment will subject the salamander to the moist paper towel of another male salamander and a control visual cue (c). The control visual cue is a video depicting the same background present in the other visual cue, only this time there will be no salamander in the clip.
Treatment 3 (CV): This treatment is made of a control olfactory cue (C) consisting of a moist paper towel that will have spent 5 days in a salamander cage devoid of a salamander. The visual cue is a video of a salamander this time.
Treatment 4 (CC): This is the complete control treatment. Both the visual and the olfactory cues are controls; this treatment has no salamander smell or image in it.
As the “cue isolation” name suggest, I will attempt to isolate the treatment that solicits the strongest behavioural response in the salamanders. For obvious reasons, I expect the OV treatment to elicit the strongest response. I am also very interested in finding out how the OC and CV treatments compare to a treatment where both sensory modalities (OV) are stimulated.
Each treatment will last 15 minutes unless the salamander escapes the testing area. This is not necessarily a bad thing, mind you, as I am also recording “latency to escape”, meaning how long it takes for the salamander to escape. This information could be valuable because this demonstrates a certain level of distress. One could predict, for instance, that salamanders undergoing the OC, CV and OV treatments will be much more likely to escape then the ones undergoing the CC. As you can imagine, I have to be very vigilant when running this experiment – I don’t want to lose any of my little guys!
How does a salamander behave anyways?
The red-backed salamander is territorial. This means that it does not take kindly to intruders. A face-off between two salamanders will usually determine which one is dominant and which is submissive. A salamander that looks directly at an intruding salamander or that lifts its trunk off the ground when confronted with an intruder, often arching its back like a cat, is displaying dominant behaviours meant to intimidate. These behaviours can sometimes lead to biting although they never bite to kill.
On the other hand, a salamander that looks away from an intruder or that lays its entire body, including its head, flat against the substrate is being submissive and might very well lose its highly prized territory. Finally, behaviours like running away, climbing the walls or hiding underneath the substrate are all called “escape” behaviours and, once again, these do not bode well as to the salamander’s chances of maintaining its territory.
During each treatment, I will record the behaviours I observe, their length as well as their location. A statistical analysis will help me interpret the data I collect and determine if there is a significant difference in behaviour between each treatment.
In the grand scheme of things, this is a rather simple experiment. I can’t imagine what minutiae chemists, bacteriologists or physicists have to demonstrate when planning and performing the experiments that make them great. One must analyze every little aspect and anticipate any problems one might encounter. For instance, previous studies have shown that it takes five days for the salamanders to establish a territory by laying down chemical cues onto the substrate at the bottom of their cages. That means that I can only perform my experiment three nights a week, given that I feed the salamanders on Thursdays and that I clean their cages and replace their paper towels on Fridays. I have to wait until Tuesday to experiment with proper male olfactory cues because otherwise my cues won’t be valid. I can run certain trials, the ones that use control olfactory cues, on Mondays however. This will allow me to complete experiment 1 and 2 before the end of the semester.
Truly, it is of the utmost importance that I stay on top of things so that everything goes smoothly. Despite having realized that I do not want to pursue zoology as a career anymore, I am as emotionally invested in this experiment as ever. It is my belief that this experiment is worth doing well. With a little bit of luck and some careful planning, I might just make a decent contribution to neurobiology and the science of animal behaviour. Here’s hoping!