Topic 4 - Microevolution

Question 1

Microevolution vs. Macroevolution

Answer 1

Micro
- Requires genetic variation
- Evolution of a community or population

Macro
- Evolution of an entire species across long periods of time

Both require genetic variance…
- Genetic drift
- Gene flow
- Natural Selection
- Mutations

Question 2

Random Mating vs. Non Random Mating

Answer 2

Random
- Genotypic variation through allele frequency

Non Random
- Alters homozygosity and heterozygosity through allele frequency

Question 3

What is inbreeding, inbreeding depression with hypothesis’s associated, and inbreeding avoidance common in species

Answer 3

Inbreeding
- mating with related individuals
- less genetic variation
- more homozygotes

Inbreeding depression
- Decreased fitness
- Can impact health
- Dominance hypothesis; recessive alleles decrease fitness, effects are usually masked in heterozygotes, and increase in homozygosity will increase phenotypic expression therefore decreasing fitness
- Heterozygote advantage; increase in fitness, decrease in breeding

Inbreeding avoidance
- kin recognition
- dispersal
- delayed maturation

Question 4

Different types of mutations, their relative frequencies, and their effects on fitness

Answer 4

Types of Mutations
- Point mutations; substitution, deletion
- Large scale; chromosomal structure altering

Frequency
- Rare and when they do occur are usually more destructive then beneficial

Effects
- Most have no effect on fitness

Question 5

Gene Flow and its effects

Answer 5

What is it
- The migration of genes from one population to another

Effects
- Gene flow rates > mutations hence more noticeable
- Can impede local adaptation which could reduce fitness

Question 6

Genetic Drift and its differences when population size varies

Answer 6

What is it
- Random changes in allele frequency across generations

In different populations…
- Smaller; Stronger and causes larger changes in next generation
- Larger; Weaker, diluted, less changes in allele frequency

Question 7

Bottlenecks / Founder event and their effects

Answer 7

What is a bottleneck event
- An event that quickly eliminates a large portion of a population causing less variation in genes between surviving organisms and in the next generation

What is a founder event
- When a group colonizes a new area isolated from others

Effects
- Enhances genetic drift
- Consequences will arise with population persistence and future adaptation

Question 8

Criteria needed for natural selection

Answer 8

Criteria
- Population varies in a trait
- Association with trait and reproductive success
- Trait is heritable

Natural selection acts on phenotypes

Question 9

Fitness and its advantages

Answer 9

What is it
- Contribution of an individual to the next generation

Advantages
- Survivorship
- Fecundity (Lonely and emotionally stable asf)
- Mating success (No relationship with no game)

Question 10

Other forms of selection (condition based)

Answer 10

Positive frequency dependance
- Selection for phenotype strengthens as phenotype becomes more common, eg. predators avoid poisonous butterflies

Negative frequency dependance
- The more rare the phenotype the greater the fitness, eg. some fish have mouths on left, some have it on right, prey adapt to common trait so it’s better to have the rarer trait, until it becomes common