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Flashcards in rodents and behavioural light aversion Deck (9)
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1
Q

What are Tinbergen’s 4 questions on behavioural research?

and how does it apply to rodents?

A

1. Function - What is it’s survival value?

Why do rodents need to detect differences in light levels?

2. Evolution - How did this behaviour evolve?

What caused the evolution of irradiance detection?

3. Ontogeny - When does this behaviour develop?

4. Causation - What are the mechanisms that cause this behaviour?

How do rodents detect changes in light?

2
Q

Why do rodents need to detect differences in light levels?

A

Predation pressure has generated anti-predator defences

  • physiological
  • morphological
  • behavioural

prey species are most at risk of predation during foraging - creates a trade off eating and vigilance

-> detecting differences in light levels allow rodents to make better decisions on when and where to forage

3
Q

Why do rodents need to detect differences in light levels?

A

Perceiving risk and predicting when it is safe uses direct and indirect predation cues.

-direct cues

visual

tactile

auditory

olfactory

-indirect cues

habitat structure

illumination

4
Q

Why do rodents need to detect differences in light levels?

A
  • Illumination
    (a) helps predators to see better
    (b) makes prey movement much more noticeable
5
Q

What caused the evolution of irradiance detection?

A

Nocturnal bottleneck hypothesis

  • early mammals competed with reptiles (e.g. dinosaurs)
  • reptiles are ectothermic -> active during the day
  • predation pressure/competition from reptiles drove endothermy in mammals
  • endothermy gave the ability to occupy other niches, including splitting temporal niches into day vs night activity

_______

-> successful nocturnal lifestyle requires:

a) detection of the onset of dusk

b) detection of changes in ambient light during darkness

6
Q

How do rodents detect changes in light?

A

1. Biological clock

-synchronises physiological and behavioural events around the 24 hr day

2. Changes in lighting at dawn/dusk

-most reliable indicator of what stage of the day it is

3. Light information

-interpreted by the master circadian pacemaker (suprachiasmatic nuclei)

7
Q

How do rodents detect changes in light?

A

whit a subset of cells on their retina that are intrinsically sensitive to the light

Photoreceptors

-Rods (image forming vision)

sensitive to light: therefore can operate in dim lighting

support right vision

-Cones (image forming vision)

less sensitive to light; require well lit environment to operate

allow colour vision

four types of cones (humans =3; birds =4; rodents =2)

-third/new receptor (non-image forming vision)

keeping circadian rhythm

pupillary light reflex

melanopsin (found in retinal ganglion cells) = photopigment in the new receptor that absorbs light (not present in rods/cones)

8
Q

why is research to study rodents and behavioural light aversion important?

A

“…research aims to improve
conservation outcomes in New Zealand by
testing new methods of preventing
reinvasion by rodents at sanctuaries…”

9
Q

How is rodents and behavioural light aversion research applied in the field in NZ?

A