BIO 220 Lecture 1

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8 Apr 2012
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BIO220H1S
Lecture 1
Background reading- pp.113-119, assigned reading: 124-130
Genes, Environment, and Behaviour:
Genes, environment and phenotype
Phenotypic plants and reaction norms
The evolution of behaviours
Two classes of scientific questions
Proximate Causes: How/What?
How can an individual manage to carry out an activity?
How do mechanisms within an animal work to produce a particular behaviour?
Ultimate Causes: Why?
Why an animal has evolved this behaviour?
Tinbergen came up with the notion of Ultimate Causes.
Z (phenotype)= G (genes)+E (environment)
The Rover-Sitter Polymorphism: Variation within a Population
Maggots of fruit flies can be kept in Petri dishes which have 2 substances in them-yeast and
agar. The maggots feed on the yeast and therefore forage on the trails of yeast, but when
there are patches of yeast, some maggots move more and some less.
There are to be 2 types of foraging behaviour in the larvae- Rover and Sitter where the
Rover moves more, but it tends to be food-related because if you replace agar with yeast,
the differences stop.
The sitters tend to stay on their own patch of food while the Rovers will move around even
off of the food patches but they are able to find other food patches
When measuring the amount of movement, you’ll see sitters move less.
If you take a sitter male and a rover female, you’ll find that almost all offspring are
rovers, so there may be dominance in Rovers.
This shows a standard Mendelian relationship.
What do the foraging alleles produce?
PKG- is an enzyme involved in cell signalling
Expression is located in nervous system, gut, and brain which would make sense if it
affects foraging behaviour
Can you turn a sitter into a rover with a single gene?
When measuring the foraging behaviour between rovers, sitters that host the rover gene,
and transgenic which are sitters with this rover gene given, you see that the transgenic is
much closer to the rover itself and has a closer PKG activity to the rover than the sitter
Z=G+E
Z= phenotype; G= genes; E= environment
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