1. Genetics

2. Genetics and Behaviour
For behaviour to be affected by natural selection, some variation in behaviour must be inherited
If not, the characteristics could not be passed on right?
Otherwise, could contribute to fitness, but could NOT evolve
Remember, only heritable, genetically transmitted variation can be affected by selection

3. Introduction
‘Trying to determine how much of a behaviour is due to genetics and how much is due to the environment is like trying to determine how much the area of a field is caused by its length and how much by its width’
Donald Hebb
Nature v. Nurture is a stupid argument

4. Key Terms Gene Genotype Phenotype Chromosome Locus Allele Diploid
Haploid
Gamete
Zygote
Recessive
Dominant
Homozygous
Heterozygous

6. Note that it is not the case that the chromosomes just pair off, there is also recombination
So, each sex cell is a little bit different

7. Mutation is the ONLY source of new genetic material
This Recombination is the source of much genetic variation, and it occurs in all but the simplest organisms
Mutation is the ONLY source of new genetic material
Most mutations are bad, usually lethal
Some are neutral
Some (very few) confer an advantage

8. How DNA works Base pairs Adenine Thymine Cytosine Guanine C -> G
A -> T

9. DNA and genes Genes encode proteins DNA -> RNA RNA -> Proteins
Proteins -> phenotype
Environment -> genes
Though some genes are less responsive than others

10. An Example Human Ocular cutaneous albinism
I wonder where that example came from…..
Single gene for the production of melanin
A – normal
a - bad
Dominance / Recessive relationship
AA, aA, Aa all lead to normal, aa leads to me

11. Phenotypically normal
Rick and Leslie
Aa and Aa
Or some variation
aA and Aa
Aa and aA
aA and aA
Phenotypically normal

12. 1 in 4 chance of having a kid with aa
They did, on June 23, 1965
My genotype MUST be aa because there is no dominance

13. Their kids could carry the allele, assuming they do
They got the looks, but I got the brains……..
Danny and Stephanie may be carriers, or they may not be, they are phenotypically normal
Their kids could carry the allele, assuming they do

14. My kids MUST carry the allele, as they had an a from me, and, an A from Isabelle
We know they got an A from Isabelle by looking at their phenotype

15. Behavioural Effects I don’t spend much time in the sun
I have very poor vision (20/200, melanin guides the growth of the visual system)
No binocular vision
Can’t drive a car
Not very good at baseball
Huge IQ…….

16. Partial Dominance Telleogryllus oceanicus and T. commodus
Males call to attract mates (function)
Song is species specific
Male hybrids produce hybrid song
Female hybrids prefer hybrid song.

17. Another cool example Mutant hamsters Martin Ralph Tau gene
TT normal 24 hr cycle
tt 20 hr cycle
Tt or tT gives 22 hr cycle

18. Teenage Mutant Ninja Hamsters
Single Gene effect
Affects brain development
SCN specifically
May be cognitive effects

19. Learning Mutants in Drosophila
The white rat of genetics
Dunce
Amnesia
Stuck
Coitus interruptus
Bang sensitive
Per
This one is cool…

20. So why are there different alleles?
On the surface, if some allele is better than some other, why does it not replace all other alleles?
Neutral alleles?
Environmental fluctuation
Heterozygote superiority
Frequency dependent selection
And, of course, mutation

21. So, What Does it All Mean? What does ‘a gene for behaviour’ mean?
Behavioural difference caused by genetic difference
Does not mean that a complex behavioural sequence is caused by a single gene
Many other genes contribute to behaviour
Some difference must be caused by genetic differences
Just because something has a genetic basis does not make in unchangeable!!!!

22. Remember, Genotype is NOT Phenotype