Transcript Neurobiology/ Behavior

Neurobiology/
Behavior
By: Anam Saeed
Sandya Kumar
Kendra Wang
E.1.1. Define these terms in the context of
animal behavior.
• Stimulus
• Response
• Reflex
Stimulus
● Stimulus (pl. stimuli) - Change in the environment (internal or
external) detected by a receptor.
○ E.g. sunrise, a sound, increase in blood sugar.
● External stimuli refers to touch, pressure, heat. Internal
stimuli refers to the stimuli being produced by body
components.
● Stimulus is capable of evoking response in an organism
Response
•
Response - Change in organism due to the stimuli; it is an
action or movement that occurs due to stimuli
● Instincts are automatic behavioral responses to stimuli. This is
known as FAPs (Fixed Actions Patterns)
○ FAPs and Instincts are the results of natural selection. The
most effective automatic responses to stimuli give the
individual a survival and/or reproductive advantage, and so
they are passed on.
Reflex
● Reflex - A type of response that is rapid and unconscious e.g. the
response to pain
● Stimulus is a detectable change in the internal and external
environment, and when applied to sensory receptors (e.g. sensory
neurons) it is what causes your reflex.
● Reflexes are the product of natural selection. Rapid and unconscious
responses allow for danger avoidance with minimal harm to the
organism (Pain is a good thing!)
○ The pain reflex is moderated by the spinal cord rather than the
brain -- shorter paths, faster responses and no conscious
decisions needed.
E.1.4. Explain how animal responses can
be affected by natural selection.
Natural selection requires:
● a change in the environment
● various phenotypes
● a genetic basis to this variation
If the organism is evolving then we might expect to observe a
change in the frequency of heritable characteristics
Example 1: European Blackcap (Sylvia atricapilla)
migration patterns
Phenotypic variations is in the direction
of migration (behavior)
Normal/Original FAP:
● Chicks hatch and fly Southwest to
Spain for the winter (migration to
avoid harsh winters)
Alternate behavior:
● Some flew Northwest to the UK
where birdfeeders provide easy
sources of food
Example 1 cont.
Advantage:
● Shorter flight distances and easy supply of food from bird enthusiasts
allow blackcaps to return to German breeding sites ahead of Spanish
migrants and be more reproductively successful
Natural Selection:
● Genes for Northwest migration passed on and proliferate in population
Example 1 cont.
Experimental Evidence:
● Eggs are taken from both populations of Blackcap. Northwest
hatchlings flew Northwest, even though there were no parents to follow
- likewise with the chicks of Southwest migrators - strong suggestion of
genetic basis for direction in migration
Conclusion:
● Genetic and morphological differences are now apparent between the
two populations.
Example 2: Prey preference in the Garter Snake
(Thamnophis elegans) of California
Normal/Original FAP:
•
Coastal snakes diet includes
amphibians and the Banana
slug (Ariolimus californicus)
Alternate behavior:
•
Inland snakes diet main
component frog, leach and fish
(slug is absent)
Example 2 cont.
Natural Selection:
The difference between the coastal and inland Garter snake is genetic,
the gene allows the snake to detect the molecule that is the slugs
‘smell’. In other words the sense of smell of the snakes is different.
The evolution of ‘slug smelling’ in coastal species is an adaptation
made in those regions. Those individuals with the ‘slug smelling’ gene
found more or better food than ‘non smellers’ , through better more
successful reproduction this gene become more frequent in the
population.
•
•
Example 2 cont.
Experiment Evidence:
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●
●
In an experiment pregnant snakes from the two regions have been collected.
Inland and Coastal animals are isolated from each other.
The hatchlings are offered Banana slug food over a 10 day period
Offsprings of Coastal ate 60% of the Banana Slugs while the Inland ate 20% of
the Banana Slugs.
Conclusion:
●
●
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Coastal Garter Snake eat more Banana slugs than Inland Garter snakes
Behaviour differences are genetically based
Two populations have diverged due to a difference in behaviour (not speciation,
yet).
E.6.5. Explain how mate selection can lead to
exaggerated traits.
Success of an organism can be measured by:
Quality of the offspring
Capacity to breed (Reproductive fitness)
•
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Through natural selection, the features improving a male's
chances of successfully competing with other males for
the best mate (mate selection) will become more
dominant.
E.6.5.
Exaggerated traits, called “ornaments”,
Likely to attract female attention
Promote successful reproduction
These traits will be selected for, although they may increase
predator attention and diminish the survival prospects of the
individual.
•
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- The evolution of these traits in a particular gender has led to
the marked sexual dimorphism of certain species.
Example of mate selection leading to exaggerated
traits
Feathers of the peacock
Male peacock displays and on the
basis of a ‘good’ display, he will be chosen
by the rather dull female peacock for
reproduction.
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This feather ‘display’ is regarded as
an ‘exaggerated trait’, where such traits are
believed to have evolved by sexual selection.
E.6.6. State that animals show rhythmical
variations in activity.
Animals show behaviours that follow rhythmical
variation, for instance,
Diurnal (daily) cycles
Lunar cycles (monthly)
Seasonal changes
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E.6.7. Outline 2 examples illustrating the adaptive
value of rhythmical behavior patterns.
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Grizzly Bears
o
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Grizzly bears tend to hibernate during the winter.
They undergo a period of inactivity due to metabolic depression.
Hibernation conserves energy and is therefore of value during winter months when
food availability is low and cost of hunting is high.
Corals
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In many species of coral, males and females release their gametes at the exact same
time of the year (mass spawning).
The advantage of such behaviour is that it increases the chances of the male and
female gametes undergoing successful fertilisation.
Spawning may be triggered by a number of factors, including temperature (seasonal)
and moonlight (lunar).
ACTIVITIES
Activity #1:
Imagine touching the hot surface of a stove or the metal part of the seatbelt
in a car during the middle of June. Now explain each step of how you
reflexively took your hand away. Include words such as stimulus,
response, and reflex.
Activity # 2:
JeOpArDy
Activity # 3 (if there is time):
and BINGO was his name O!