Topic 1 - Lecture 2.2: Proximate Mechanisms Dr Ott Flashcards
What is quantifying behavioural phase state?
Quantification of how much a gregarious locust resembles a solitarious locust.
- Generate a solitarious and gregarious spectrum to see where the individual locust fits.
S and G locusts differ in multiple behavioural characteristics.
Assay layout + analysis
- Arena ( rectangular box containing locusts
- 2 partitions ( 1 with stimulus group)
- Individual locust placed in a hole within the arena ( either reared in isolation or a crowd).
- Locust = observed for 10 mins
Isolation state - analysis
- Locust makes a beeline away from the stimulus group.
- Sits far away + hides itself
Crowded state - analysis
- Locust moves out and rapidly towards the stimulus group.
- Spends a lot of time near it throughout the 10 mins
Analysis method
In research literature computer tracking is used to tract locust trajectory.
Solitarious locust - movement analysis
Doesn’t interact with other locusts and doesn’t move around much.
- stays at rest
Gregarious locust - movement analysis
Spends more time interacting with other locusts + more likely to jump around the arena.
- Cover more ground due to rapid movements
Logistic regression model
Technique used by researchers to combine the different measures of behaviour.
- Difference between two phases combined with the different traits that distinguish solitarious and gregarious into a single measure of faith state = Pgreg
Pgreg
Probability of being gregarious
- Runs between 0 and 1.
Solitarious Pgreg
Pgreg = close to 0
Gregarious Pgreg
Pgreg = close to 1
What sensory inputs drive behavioural gregarisation?
2 sensory pathways work independently:
1. Smell and sight
2. Touch stimuli of hind leg ( particularly the outer femur)
Smell and sight - sensory pathway
No need for physical contact, combinations of sight and smell of other locusts is enough to cause changes.
Touch stimuli of hind leg ( particularly the outer femur)
Stimulating the hind leg sensation without exposure to other locusts is enough to cause a change.
Role of serotonin in phase state change
Can cause gregarisation without the presence of other locusts.
- levels of serotonin increase in the thoracic tract of locusts
- the levels increase and drop back down
Serotonin is necessary for gregarisation…
The serotonin receptor agonist blocks gregarisation in presence of gregarising sensory input
Serotonin is sufficient for gregarisation…
Serotonin receptor agonist causes gregarisation in the absence of the gregarising sensory inputs.
