Genetics, Selfishness and Altruism

Question 1

What is heritability?

Answer 1

Heritability is the proportion of phenotypic variance in a population that can be attributed to genotypic variance. It varies between 0 and 1, with 0 being completely environmentally determined and 1 being completely genetically determined.

Question 2

How can heritability be measured?

Answer 2

1) Breeding experiments
2) Comparisons of natural genotypes
3) Measurements of mutants

Question 3

Describe the experiment that looked at mating speeds in Drosophila flies

Answer 3

In Drosophila, there are lots of behavioural mating phenotypes.
Mating behaviour and copulation time is a very complex behaviour.
Under normal circumstances, flies mate for around 6 minutes.
This can be controlled by genetics if flies are chosen to mate for longer/shorter periods of time.

Question 4

Give an example of heritability in wild populations

Answer 4

Blackcap (Sylvia atricapilla) migration behaviour.
Main breeding population in Germany, migrate SE to Greece, SW to Spain or NW to Britain.
Measured using emblem funnels - birds see the sky, inkpad at the bottom, restlessness and direction can be measured.
Easy to select individuals who are more likely to migrate.
When breeding hybrids, they show intermediate migration.

Question 5

Describe the genetic control of behaviour

Answer 5

Most heritable behaviour is polygenic
Most behaviour is also learnt and dependent on interactions with the environment
There are some rare monogenic examples e.g. smell in dunce flies

Question 6

Give a timeline of the evolution of behaviour

Answer 6

3.6 billion years ago - Earliest known evidence of life
2 billion years ago - First eukaryotes
1.5 billion years ago - First eukaryote animals
800 million years ago - First multicellular organisms evolved
570 million years ago - First vertebrate organisms evolved
Behavioural evolution has occurred for the last 500-800 million years

Question 7

What is altruism?

Answer 7

The behaviour that increases another individual’s fitness at a cost to one’s own fitness.

Question 8

What is the problem with ‘for the good of the species’ argument?

Answer 8

Selection occurs on individuals and genes
Group selection would be inefficient
Selection for selfishness in individuals overcomes group co-operation
Few/no empirical examples of group selection

Question 9

What are the two types of altruism and how did they evolve?

Answer 9

Kin selection - Evolved through inclusive fitness.
Reciprocal - Evolved through expecting the benefit given to the receiver to be reciprocated to the donor at a later date.