W1 - Animal Behaviour (NS & Adaptation) [Dr. Madikiza] Flashcards
(38 cards)
Types of selection? (2)
- Artificial selection (AS).
- Natural selection (NS).
Artificial selection?
= process by which heritable traits (genetic basis) favoured by human actions become more common in successive generations.
How do traits become common in successive generations through Artificial selection?
Humans “select” certain varieties of an organism over others, by implementing breeding programmes that cause one or more varieties to increase in frequency.
AS attributes? (3)
- Happens at microevolutionary scales (microevolution).
- Has an endpoint in mind (as it is done by humans).
- Doesn’t care about increasing survival & reproductive success but focuses on what is desired by humans (eg, to see if a behaviour has a genetic basis).
Eg of AS?
Dog breeder with poodles.
Explain poodle eg?
If you want to produce a teacup poodles (Generation N), select individuals with similar traits to what you want from Generation 1 & Generation 2 breeds.
NS?
=
NS attributes according to Darwin? (5)
- Individuals differ in their morphology, physiology and behaviour (variation).
- Some of this variation is heritable.
- There is competition between individuals for scarce resources (food, mating partners, space).
- The best competitors will leave more offspring than others. These offspring will inherit their parents’ characteristics & through NS over generations will come to be adapted to their environment.
- If environment changes, then new variants will appear & so NS can lead to evolutionary change.
NS attributes in general? (2)
- Has no endpoint in mind (as it is done by nature).
- Nature selects a trait/phenotype that is frequent, as long as the trait (good or bad) increases the survival & reproductive success of an organism at that period of time.
NS summary? (4)
1) If one variety of a trait helps individuals to survive & reproduce better in their environment than another variety of the same trait,
AND
2) If the trait in question can be passed across generations,
THEN
3) NS is occurring!
4) Therefore, nature “selects” those traits that enhance reproductive success.
Behaviour?
= a response to a stimulus that often has a genetic influence (via pathways, etc).
NS criteria/prerequisites (How NS operates)? (3)
- Variation.
- Fitness consequences/Fitness benefits.
- Modes of inheritance.
Variation?
= must be in the trait observed.
Types of variation? (2)
- Genetic variation.
- Environmental variation.
Genetic variation?
= variation that is caused by genetic differences in the trait.
What causes those genetic differences in the trait? (3)
- Mutation.
- Genetic recombination.
- Gene flow/Migration.
Mutation?
= any change in genetic structure/DNA sequence.
Genetic recombination?
= process during cell division where pairs of chromosomes line up & “cross-over”.
Gene flow/Migration?
= when genetic variants of a trait can also enter a population, whereby individuals migrate in from other populations.
Environmental variation?
= variation that is caused by rapid changes in the environment.
What causes those rapid changes in the environment? (2)
- Humans (perhaps by deforestation, poaching, etc).
- Global warming.
Fitness consequences?
= when the observed variations in a trait must have fitness consequences.
Fitness?
= the expected “contribution” of an individual to the next generation, relative to other individuals.
Contribution?
= mean number of reproductively viable offspring that an individual produces.
