Topic 1 - Lecture 2.1 Phase Change In Locusts ( Introduction)

Question 1

Phenotype

Answer 1

All the traits that link between genes and environment.

Question 2

Two different classes of phenotypes

Answer 2

• Variations with in one particular trait.
• Describing the totality of all traits

Question 3

Gene environment interaction (G x E)

Answer 3

Same set of genes can give a variation of phenotypes depending on the environment of an organism.

Question 4

Phenotypic plasticity

Answer 4

The ability of organisms to change in response to the environment.

Question 5

Context dependant behavioural plasticity

Answer 5

Behaviour changes rapidly in response to the situation of the environment - hence behaviour is a a very plastic aspect of phenotypes.

Question 6

Learning in animals

Answer 6

An experience driven change in behaviour + the phenotypic plasticity.

Question 7

Locusts

Answer 7

• Desert locus species
• Found in northern Africa + Arabian peninsula when there are no outbreaks.
• During outbreak they swarm the north, south and east of these zones + their surroundings
• Undergo huge population number + density changes

Question 8

Density changes

Answer 8

Drive an extreme form of phenotypic plasticity.

Question 9

Two phenotypes of locusts

Answer 9

• Solitarious phase
• Gregarious phase

Question 10

Solitarious phase traits

Answer 10

Occur at very low densities:
- Cryptic camouflaged colouration to hide from predators.
- Slow creeping gait behaviour to avoid conspicuousness
- Crepuscular = predominantly active between dawn and dusk.
- Repel one another

Question 11

Landscape climate changes drive outbreaks

Answer 11

Due to heavy rainfall ( e.g brought by cyclone ) - landscape becomes lush:
- Desert lakes form in sandy ridges + vegetation increases
- Increase in vegetation = locusts concentrated into small condensed areas for food.

Question 12

Phase change

Answer 12

The transformational change driven by changes to the environment.

Question 13

Gregarious phase change traits

Answer 13

Crowding of locusts = transformational changes
- Cryptic to warning bright colours (yellow + black)
- Become active and mobile ( rapid gait movements)
- Diurnal (active during the day)
- Aversion to attraction (therefore crowding is self- maintained)

Question 14

Insect polyphenism

Answer 14

Two or more distinct phenotypes are produced by the same locust genotype

Question 15

Locust phase polyphenism

Answer 15

Evolution in adaptation to extreme unpredictable changes in availability + distribution of resources (food resources + egg laying sites)
- Absence / presence of other locusts is the sole driver of the t phase changes
- Transition initiated at any time in locust’s lifetime.
Changes time scales include:
- behaviour = hrs to days
- colour = days to lifetime
- full morphology = lifetime to generations

Question 16

Egg laying sites

Answer 16

Animals need certain soil + moisture for egg survival.
If all locusts gather together to lay eggs that contributes to crowding.

Question 17

Generation of locust phase changes in lab

Answer 17

To discover how behavioural plasticity comes about by studying proximate mechanism driving the phenotypic plasticity of behaviour.