Block 1 Flashcards
Phenotypic plasticity
– Animals can change in response to changes in their environment.
– Behaviour is one (very plastic) aspect of the phenotype.
Learning = experience-driven change in behaviour,
= phenotypic plasticity
Solitarious phase of locus
Behavior: Shy, avoid other locusts, slow movement, dispersed.
Morphology: Dull-colored, smaller body size.
Physiology: Low metabolic and reproductive rates.
Ecology: Minimal impact on crops.
Gregarious phase
Behavior: Highly social, form large swarms, increased activity.
Morphology: Brightly colored, larger body size, strong wings.
Physiology: High metabolic and reproductive rates.
Ecology: Devastates crops, major agricultural threat.
Trigger: Population density and tactile stimulation (e.g., crowded conditions).
Why does locus phase Polyphemus occur
-evolved in adaptation to extreme and unpredictable changes
in the availability and distribution of resources.
-sole direct driver is the presence / absence of other locusts.
-can be initiated at any time during the life of a locust.
-changes unfold over very different time scales e.g. changes in behaviour can occur from hours to days etc.
How to quantify the Behavioural phase state
Solitarious and gregarious locusts differ in multiple behavioural characters.
It’s a behavioural syndrome so there’s difference ranges e.g. autism high functioning and ,ow functioning
- we can see the behaviour in the behaviour arena .
- can have extreemly solitarious and low its a range between the two extremes
What are the sensory inputs drive behavioural gregarisation? ( make little locus go from solitarious phase to gregarious phase)
- crowding
-sight and smell
-hind leg touch
Can measure
Serotonin in thoracic ganglia
- freshly crowded solitarious locus show a 9-fold increase in the amount of serotonin in the CNS.
- only in the thoracic ganglia not the brain
-there is a correlation . Go into more detail
Serotonin in thoracic ganglia
- freshly crowded solitarious locus show a 9-fold increase in the amount of serotonin in the CNS.
- only in the thoracic ganglia not the brain
-there is a correlation .
-has behavioural effects e.g. increases social interactions
Metaplasticity
It means an animal’s ability to change can itself change based on experience or environment.
Is plasticity itself plastic? → Yes, it can increase or decrease over time.
Are some animals more plastic? → Yes, those in changing environments adapt more.
Associative learning in locusts:odour-food conditioning
Experiment Overview
Locusts are trained to associate an unfamiliar odor with food. After training, their response to the odor (without food) is tested to see if they have learned the association.
Training Process
Odor Presentation – A neutral smell is introduced.
Food Reward – The odor is paired with a palatable artificial food paste.
Repetition – The pairing is repeated multiple times to reinforce learning.
Testing (Learned Response)
If the locust moves toward the odor or shows feeding behavior, it has learned the association.
Key Findings: Behavioral Phase Differences in Learning
Locust Type Learning Response Why?
Solitarious Locusts Fast aversive learning (avoid bad food quickly) Learn from taste immediately to avoid toxic food.
Gregarious Locusts Slow aversive learning (delayed avoidance) Learn from post-ingestive feedback (realizing food is bad later).
Newly Gregarized No aversive memory (forget previous food learning) Likely to match the swarm’s feeding behavior.
Using the conditioning methods can solitarious locusts Learn about toxics
-they can be conditioned with toxins like nicotine to avoid them
-In solitarious locusts, this learning is fast and taste-mediated, helping them quickly avoid toxins. Gregarious locusts learn more slowly, relying on post-ingestive feedback after ingesting the food. Newly gregarized locusts initially show no aversive learning due to suppressed mechanisms.
Proximate explanations,
ultimate explanations.
In locusts, solitarious phase involves fast aversive learning to avoid toxins, relying on taste to quickly detect harmful food, which aids survival. In the gregarious phase, learning is slower, with locusts depending on post-ingestive feedback after consuming food, allowing them to take in more food despite potential toxins. Newly gregarized locusts show no immediate aversive learning, as both taste and feedback mechanisms are suppressed, reflecting their focus on group dynamics rather than individual toxin avoidance. These differences help balance costs and benefits related to food intake and survival.
Method of quantifying the behavioural phase state in locusts
Behavioral Tracking (500 s):
The behavior of 100 solitarious and 100 gregarious locusts is tracked over a period of 500 seconds.
Behavioral metrics such as movement speed, direction changes, and proximity to other locusts are recorded.
Logistic Regression Model:
A logistic regression model is used to analyze the behavioral data.
This model provides a single quantitative measure called P
greg for each locust.
Pgreg -represents the probability that an individual locust is behaving in a gregarious phase.
Values range between 0 and 1:
P(_{\text{greg}} = 0:** purely solitarious behavior.
P(_{\text{greg}} = 1: fully gregarious behavior**.
