Lecture 12: Behaviour and Genetics Flashcards
What was “The Origin of Species”?
-Adaptation to environment and origin of new species as closely related processes
-Darwmin dent use word “evolution” in 1st ‘The Origin of Species’ instead he used ‘Descent with modification’
-Descent: Existence of traits bc they were passed down from a previous ancestor
-Modification: Variation in such traits shaped by seclection
What 2 questions of Tinbergen are we talking about?
-Functional- modification
-Evolution- descent
What was Mendel’s law of inheritance?
-Discovery of ‘inheritance factors’ (later ‘factors’ called genes)
-Identified consistent patterns based on dominance and recessive alleles 3:1 colour
What is the genetics of behaviour?
-Inheritance of behaviour is complex
-“it has been found repeatedly that no one genetic mechanism accounts exclusively for a particular kind of behaviour” which is what makes it so difficult
-Traits can be influences by many genes (polygenic)
What is simple vs complex inheritance?
Simple: Simple genetic basis: Distinct different colours and no intermediate (ex green or yellow)
Intermediate: Complex genetics: have intermediates ex can have mixture pattern so anything in-between
-Can be result of controlling multiple allies
What is an example of changes in gene expression over time?
-Worker bees live 4-7w and change roles to nursing and foraging
-Accelerate, delay or even reverse their behavioural maturation to serve the needs of their colony
-Changes in brain genes, so complex
What is the simple equation for the genetics of behaviour?
Phenotype=genotype+Environment
P= Traits we can observe/measure
G= Genetic make up
E= Environmental (non-genetic) influence
-Nature vs nurture
can get more difficult by adding Genotype*Environment onto end
-If out into different environment they will behave differently/not perform the same
What is heritability of traits?
Heritability: Extent to which variation in a trait is due to genetic
-Always pos, range 00-1 (or 0-100%)
-The higher the number the more heritable
-Not fixed! varies between populations or environments (ex breeds can have different heritabilities for same traits)
ex milking temperament differs from cow in CA vs Brazil
What does evolution mean?
-Derived from latin ‘evolutio”–> ‘an unrolling’
-Originally used to describe changes in the developing embryo
-Later used to describe changes in species’ characteristics across generations
-Darwin compared species as “higher” or “lower” where now we just say animal ascended from this animal
What were the 3 broad observations Darwin explained? And what is the modern synthesis- alternative?
-Unity of life
-The diversity of life
-The match between organisms and their environment
Modern:
-Principle of variation
-Principle of genetic inheritance
-Principle of natural selection
Some additions
-Behaviour of the animal itself can modify its environment which can change the secretive pressure
-He did see role for development (epigenetic) ex stressor applied to drosophila by 13th generation effects appeared before stressor traced to genetic changes not random adaptation to the stressor
What is natural selection?
-Principle of variation
-Members of a population often vary in their inherited traits ex lady bug spots and colours affect survival-Causal?
-Individuals inherited traits gave a higher probability of surviving and reproducing tend to leave more offspring
-All species can produce more offspring that environment can support and many die
-The unequal ability of individuals to survive and reported will lead to accumulation of favourable traits in population over generations
-Survival of the fittest (genes)
-Fitness: ability to pass on genes to next generations
-Adaptation to environment
-Increase the frequency of individuals with theses traits
-Match n/w organisms and their environment may give rise to new species
How does the study with tail length relate to natural selection?
-Manipulated tail length in widow birds
-Females preferentially mated with males with elongated tails
Sexual selection: form of natural selection
-Reproduction of the fittest
-Differential fitness based on individual’s ability to pass on genes (to mate)
2 Forms:
1. Intrasexual selection: Direst competition between members of ones sex for makes (male aggression)
2. Intersexual selection: driven by mate choice (indirect competition) females decide one in this example
What does it mean when ‘animals can become locked in an arms race’?
-Athletic capabilities of predators and prey closely matched
-ex cheetah and impala are similarly athletic
-Another ex with humans is coming up with ways to close your garbage bins bc the animals (raccoons/squirrels) will open and make mess
-Overtime more ppl had protection so they were changing and making their contraptions more complex to keep up
What is artificial selection?
-Humans modify species by selecting and breeding individuals with desired traits
2 SIDES: both can occur simultaneously
- Methodical selection: Guided by predefined standards; what is ‘best’ has a goal associated with it
2.Unconscious selection: no wish or expectation to alter anything, consequences didn’t foresee
What is domestication?
-‘Process’ (takes time) whereby populations of animals change genetically and phenotypically in response to selection pressure associated with life under human supervision (evolutionary process)
3 pathways:
1. Relaxation of specific natural selection pressures (predation, starvation) chicken ex wild wanted to forage slightly domesticated just wanted food given
2.Intensified human selection for preferred traits (growth, appearance) artificial section for boy size, colour, coat
- Development of traits that are genetically correlated to ones selected (potentially unwanted consequences) ex PSS selected for muscle growth has introduced mutation for gene so heterozygous more susceptible
