Flashcards in Animal behaviour-Introduction Deck (9)
What are Tinbergen's 4 questions that help us understand animal behaviour?
What are the mechanisms that cause it?
How does it develop?
What is its adaptive value?
What is its evolutionary history?
The first 2 questions are proximate causes and the last 2 are ultimate causes. What is meant by proximate and ultimate?
A proximate cause is an event which is closest to, or immediately responsible for causing, some observed result. This exists in contrast to a higher-level ultimate cause (or distal cause) which is usually thought of as the "real" reason something occurred (what is driving the evolution of a particular trait)
Using starlings singing, can you answer each of Tinbergen's 4 questions?
Mechanism: Increased daylight triggers hormonal changes. Air flow through the syrinx
Development: Learned songs from neighbours/parents
Adaptation: To attract mates for breeding
Evolution: Complex song evolves from simple ancestral calls
What must happen for selection to be possible?
1) There is inter-individual variation
2) Individual differences are heritable
3) Some behavioural differences increase reproductive success
Are genes involved in behaviours or is it just environment?
Behaviours/traits are polygenic (although some genes may have a v. large effect on a particular behaviour). Behaviours are usually influenced by both genetic and environmental elements
Sometimes, allelic differences in certain genes affect a behaviour. Use fruit flies (Drosophila melanogaster) as an example to explain this.
'Rover' and 'Sitter' alleles dictate how far the fly forages (Rovers move much more than Sitters). This exists due to differences in environments and how much food is accessible- e.g if there is plenty of food, sitting and eating is beneficial
What studies can be used to show/ explore genetic influences on behaviour?
Common garden studies- Guppies shoaling
Innate behaviour and learning- Laughing gulls pecking at parents' beaks, innate (genetic) and learning (environment)
Cross fostering (and twin studies)- testing different environments on genetically identical animals- done in blue tits and great tits songs
Heritability/quantitative genetics – measuring the resemblance between relatives- pedigree needed- Ballooning in wolf spiders
Isolines (isofemale lines)- taking relative-resemblance to the extreme, make “clones” by inbreeding lines for many generations until individuals from that line are pretty much genetically identical
Artificial selection – impose a selection pressure (i.e. pick those individuals that get to mate) and measure how the behaviour changes in subsequent generations
What is a more advanced way of finding out whether a gene affects a behaviour?
Use RNAseq for whole transcriptome or qRT-PCR for single gene regulation helps to find some genes of interest. Then induce mutants by X-ray or chemical mutagenesis. Then look at the change in behaviour- e.g Fruitless and male courtship in fruit flies
RNAinterference (RNAi)- Knock-down gene expression by co-opting the cell’s anti-viral machinery to cleave double stranded RNA. (basically cell chops up its own DNA)
Can be life-stage and tissue specific