Topic 1 - Lecture 2.2: Proximate Mechanisms Dr Ott

Question 1

What is quantifying behavioural phase state?

Answer 1

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.

Question 2

Assay layout + analysis

Answer 2

• 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

Question 3

Isolation state - analysis

Answer 3

• Locust makes a beeline away from the stimulus group.
• Sits far away + hides itself

Question 4

Crowded state - analysis

Answer 4

• Locust moves out and rapidly towards the stimulus group.
• Spends a lot of time near it throughout the 10 mins

Question 5

Analysis method

Answer 5

In research literature computer tracking is used to tract locust trajectory.

Question 6

Solitarious locust - movement analysis

Answer 6

Doesn’t interact with other locusts and doesn’t move around much.
- stays at rest

Question 7

Gregarious locust - movement analysis

Answer 7

Spends more time interacting with other locusts + more likely to jump around the arena.
- Cover more ground due to rapid movements

Question 8

Logistic regression model

Answer 8

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

Question 9

Pgreg

Answer 9

Probability of being gregarious
- Runs between 0 and 1.

Question 10

Solitarious Pgreg

Answer 10

Pgreg = close to 0

Question 11

Gregarious Pgreg

Answer 11

Pgreg = close to 1

Question 12

What sensory inputs drive behavioural gregarisation?

Answer 12

2 sensory pathways work independently:
1. Smell and sight
2. Touch stimuli of hind leg ( particularly the outer femur)

Question 13

Smell and sight - sensory pathway

Answer 13

No need for physical contact, combinations of sight and smell of other locusts is enough to cause changes.

Question 14

Touch stimuli of hind leg ( particularly the outer femur)

Answer 14

Stimulating the hind leg sensation without exposure to other locusts is enough to cause a change.

Question 15

Role of serotonin in phase state change

Answer 15

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

Question 16

Serotonin is necessary for gregarisation…

Answer 16

The serotonin receptor agonist blocks gregarisation in presence of gregarising sensory input

Question 17

Serotonin is sufficient for gregarisation…

Answer 17

Serotonin receptor agonist causes gregarisation in the absence of the gregarising sensory inputs.