Animal behaviour-Introduction

Question 1

What are Tinbergen’s 4 questions that help us understand animal behaviour?

Answer 1

What are the mechanisms that cause it?
How does it develop?
What is its adaptive value?
What is its evolutionary history?

Question 2

The first 2 questions are proximate causes and the last 2 are ultimate causes. What is meant by proximate and ultimate?

Answer 2

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)

Question 3

Using starlings singing, can you answer each of Tinbergen’s 4 questions?

Answer 3

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

Question 4

What must happen for selection to be possible?

Answer 4

1) There is inter-individual variation
2) Individual differences are heritable
3) Some behavioural differences increase reproductive success

Question 5

Are genes involved in behaviours or is it just environment?

Answer 5

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

Question 6

Sometimes, allelic differences in certain genes affect a behaviour. Use fruit flies (Drosophila melanogaster) as an example to explain this.

Answer 6

‘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

Question 7

What studies can be used to show/ explore genetic influences on behaviour?

Answer 7

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

Question 8

What is a more advanced way of finding out whether a gene affects a behaviour?

Answer 8

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

OR

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

Question 9

What is phenotypic plasticity?

Answer 9

When a genotype makes many phenotypes due to its environment. This can be achieved by epigenetics- e.g methylation or acetylation to change gene expression