Development of behaviour 2 Flashcards
Why is it hard to show the evolution of behaviour
Behaviour does not fossilise.
Reconstructing the evolution of behaviour is problematic.
Evolution requires a genetic basis for a phenotypic trait.
Evidence for genetic basis to behaviour.
Phylogenetic analysis
Genetic determinism.
“Strictly speaking, it is the brain, rather than the behaviour, that is inherited.”
genes are inherited not just brains and these are selected by natural selection because of their effects on the phenotype, in the brain beneficial phenotypes are likely to involve behavioural control and not morphology.
Label the brain
*frontal lobe= motor cortex (control of skeletal muscles)
-Prefrontal cortex=decision making, planning.
-Broca’s area=forming speech
*parietal lobe =somatosensory cortex (sense of touch)
-Sensory association cortex (integration of sensory information
*occipital lobe= visual cortex (processing visual stimuli and pattern recognition
-Visual association cortex combining images and object recognition.
*(cerebellum)
*Temporal lobe=Wernicke’s area (comprehending language)
-Auditory cortex (hearing)
Adaptation
Evolution by natural selection leads to organisms which are well adapted to their environment.
Adaptive characters may be morphological, physiological, behavioural, etc.
But, there must be an underlying genetic basis.
Genes for behaviour
Where’s the evidence?
Innate behaviours
Single gene control
Transgenic experiments
Artificial selection
1) Innate behaviours
E.g. Migration of eels.
Elvers can’t learn the direction of their migration from their parents.
The information must be transferred genetically.
2) Single gene control of behaviour
Mutation in fosB gene in mice affects a suite of maternal behaviours: nest building, pup rearing, etc.
a calcium calmodulin kinase mutant mice show impaired spatial learning.
3) Transgenic experiments
Drosophila typically have a 24-hour circadian rhythm.
Mutant per0 Drosophila are arrhythmic.
Injecting plasmids with the wild-type per+ gene into embryos produces flies that behave normally.
per0 differs from the wild-type by only one base pair out of the 3,500 in the gene and 137,000,000 in the genome.
The period gene also affects the inter-pulse interval in Drosophila song.
Mutant per0 Drosophila are arrhythmic.
D. melanogaster embryos transformed with a melanogaster per+ gene produce normal song.
But those embryos transformed with a D. simulans per+ gene produce wild-type song of D. simulans.
4) Artificial selection
There is a tremendous amount of evidence that artificial selection can drive the evolution of behaviours.
Laboratory experiments demonstrate that there is a heritable basis for many behaviours.
using migration of blackcap we can select to mate male and females that have a tendency to migrate and then we get a line selected for migration and subsequent generation will eventually have 100% of them migrating. If we breed those that don’t have a tendency to migrate, eventually over subsequent generations the tendency to migrate will decrease to 0%.
We can also artificially select for different mating speeds in Drosophila. We can make drosophila less choosy as well as the converse
Both of these show there must be a genetic underlying factor as it’s passed on
Genetic determinism
Genetic determinism is the notion that our genes determine who we are at every level: physical, emotional, and behavioural.
Very few biologists would agree with this.
Phenotypes result from the interaction of genes and the environment.
Nature and nurture not nature vs. nurture.
Genes vs. individuals
Some aspects of evolution are easier to understand from the point of view of the gene.
Others make more sense from the point of view of the individual.
But remember that they are like the two sides of a coin.
Phylogenetic evidence for the evolution of behaviour
Use phylogenetic analysis to reconstruct evolutionary relationships between organisms.
Use this to infer sequences in the evolution of behaviour.
human evidence showing evolution of behaviour
In the genus homo for human the first tool use olduwan was by the homo habilis, then over many years homo ergaster created more advanced tools acheulean (flint objects) lastly homosapiens evolved to create even more complicated useful tools such as a clovis tool
Animal evidence showing evolution of behaviour
The evolution of courtship displays
Gerard van Tets (1965) suggested that complex courtship displays had evolved from flight intention movements.
Phylogeny based on morphology and DNA shows a close match to van Tets’ original hypothesis
