30. Processes of evolution

Question 1

Which evolutionary processes generate evolution and which are sorting?

Answer 1

Generating: mutation, gene flow
Sorting: genetic drift, natural selection

Question 2

What are the multiple forms of mutations?

Answer 2

• point mutations (single nucleotide change)
• insertions / deletions (intels - don’t know if inserted or deleted)
• sequence (gene) duplication / amplifications
• translocations (movement of sequences)
• inversions (sequences flipped around in replication)

Question 3

Does crossing over lead to mutations?

Answer 3

Crossing over may or may not lead to mutations - always leads to variation but not necessarily mutations

Question 4

Explain mutations wider

Answer 4

Question 5

Explain gene flow wider

Answer 5

Gene flow occurs when new individuals with different genetic makeup are introduced into a certain population

Question 6

How can genetic variation arise without evolutionary change

Answer 6

1. ex: one houseplant is watered more than other → grows larger - variation without genetic change due to phenotypic plasticity (not evolution)
2. Meiosis and sex

Question 7

Explain genetic drift wider

Answer 7

Genetic drift occurs when not the whole population reproduces (not all in the “breeding pool”) → changes in genetic composition (allele frequencies drift)

The breeding pool can be representitive - less drift or less representative - more drift from the original gene pool (the larger the breeding pool - the larger the chance of a representative sample)

Genetic drift not ubiquitous (found everywhere) in large populations

Genetic drift can happen due:

• “Founder effect”: first organisms to arrive at habitat unlikely to be adabted to that habitat - founders are a random sample of the original population
• “Bottleneck effect”: population size decreases - random sampling of genes from the original population

Genetic drift cannot explain adaptation (unless well-adapted invader), usually changes in genes are invisible - synonymous

Ex: which sperm fertlises which egg

Question 8

How can the rate between synonymous and non-synonymous mutations be compared?

Answer 8

Question 9

Explain natural selection wider

Answer 9

Natural selection - process in which genetic change arises by non-random association between reproductive success and characteristics of an organism

Darwinian syllogism:

1. Indviduals vary in traits that are partly heritable
2. Some of these traits may be associated with successful reproduction
3. 1+2 together lead to genetic change from one generation to next - evolution

Evolutionary fitness - number of copies of genes that get passed on to the next generation (high fitness - lots of copies, low fitness - little copies)

Two ways of evolutionary fitness:

• Direct fitness: your own offspring
• Indirect fitness: genes carried by offspring of relatives
• Direct + indirect = inclusive fitness (evolution by natural selection is all about inclusive fitness)

Different components of evolutionary fitness:

• Survival (viability selection)
• Number of offspring (fecundity selection)
• Number fo quality mating partners (sexual selection - try to males attract and persuade females)

The components trade off: lots of E into survival → less E into number of offspring / finding quality of partner

Traits may be positively / negatively correlated with fitness components

Question 10

What is neede for evolution not to occur?

Answer 10

• No heritable variations in traits
• No associations between traits and reproduction

Question 11

Summary fo the lecture

Answer 11