Genetic Determinants of Behaviour Flashcards
Do genes or the environment play more of a role in behaviour?
Both - they interact and both influence variation
What is an example of natural variants?
Drosophila rover and sitter alleles - rovers disperse across food patches and sitters stay in one
Why might the rover-sitter polymorphism persist?
Frequency-dependent selection where fitness changes based on food patch availability
What happens when there is a high abundance of food?
Higher reproductive success of sitters
What happens when there is a low abundance of food?
Higher reproductive success of sitters
Why do population differences cause different behaviours?
Ecologically discrete populations differ in both environment and genetics (allele frequencies)
Give an example where different populations have displayed different behaviours
Shoaling behaviour in guppies - guppies that are more used to being at risk of predation shoal more tightly in lab standardised conditions when alarmed
What are innate behaviours?
Behaviours that are performed from birth - they can be adjusted by learning through life
Give an example of innate behaviours
Laughing gull (Larus atricilla) chicks peck parents beak to be fed from birth but their accuracy improves with age (learned)
Give an example of cross fostering behaviours
Cross fostered blue and great tits (child swap) - song repertoire large with aspects from birth parents and foster parents
How is heritability used to figure out the determinants of resemblance?
Use known relationships and measure resemblance - if variation between full siblings, siblings and unrelated individuals then large genetic component; if variation is similar then large environmental component
Give an example of heritability experiments
Ballooning spiders - fly using webs and wind - enabled by genetics but how often they balloon depends on parents
What are isolines?
Make clones by inbreeding lines for many generations until individuals from that line are pretty much identical
Give an example of when isolines have been used to investigate the determinants for behaviour
200 inbred lines of Drosophila, fully sequenced and then tested for traits and SNPs (increased gene component = same behaviour; increased environment component = different behaviour)
How is artificial selection used to test for determinants of behaviour?
For heritable behaviour, impose a selection pressure (pick the individuals that get to mate) and measure how behaviour changes in subsequent generations
Give an example of when artificial selection has been used to investigate the determinants for behaviour
Flight capacity in beet army worm moths - long fliers breed with long fliers and produce offspring who fly for longer
How does gene expression help uncover the determinants for behaviour?
Measure gene expression using RNAseq (whole transcriptome) or qRT-PCR (single gene): an increase or decrease in gene expression.
Give an example of when gene expression has been used to investigate determinants for behaviour
Burying beetles and parenting - sequence the transcriptome and analyse differences between parental and bi-parental beetles (867 genes differentially expressed)
How do classical mutants help uncover the determinants of behaviour?
Induce mutations by x-ray or chemical mutagenesis
Give an example of when classical mutants have been used to investigate the determinants of behaviour
Fruitless and male courtship in Drosophila - induce males with fruitless gene so that can’t distinguish male and females so flies mate indiscriminately (genetic component).
What is RNAinterference?
Knock down gene expression by co-opting the cell’s antiviral machinery to cleve double stranded DNA
Describe the in vitro process of RNAi
- Selection of target gene for gene silencing
- Designing si/shRNA specific to target gene
- Selecting a plasmid or vector
- Introducing the dsRNA to cells
- Gene expression assay
Give an example of when RNAi has been used to investigate the determinants of behaviour
Trp-A1 gene and heat avoidance in flour beetle - Arena 50% good temperature, 50% too warm; non mutants go to good side; mutants 50/50 don’t recognise the difference - gene associated with temperature recognition
What is phenotypic plasticity?
Where a genotype can make many phenotypes
Give an example of when phenotypic plasticity has been used to investigate the determinants for behaviour
Drosophila learning and memory - short, medium and long term memory and anaesthesia-resistant memory
What are the three mutant or knockdown flies training tests?
- T-maze odour assay
- Visual learning
- Complex courtship assay
What is the T-maze odour assay?
Reward in one arm, shock in the other - in future flies avoid the arm with the shock
Give an example of visual learning in flies
Comfortable cold patch marked with dot, when dot is moved to non cold dot, the flies still go to the dot
What is the complex courtship assay?
Males more attracted to females who haven’t mated, because they have more chance of reproductive success (selective advantage)
What is epigenetics?
Non-coding modifications of DNA could link environmental cues with behaviour, by making genes more or less available for expression
Give two examples of epigenetics
DNA methylation and histone modification
Give an example of when epigenetics has been used to investigate the determinants for behaviour
Maternal care by rats - only parents (mothers) change in methylation of BDNF gene across generations - poor treatment leads to poor treatment of offspring
Describe the epigenetic control of caste differentiation in carpenter ants
Soldier ants vs forager ants - knocking down Rpd3 alters histone acetylation and makes majors more likely to forage
How does behaviour drive or reinforce speciation
Assortative mating of Heliconius - QTL mapping identifies 3 loci which drive male courtship preference
