mechanisms of evolution - Week 15

Question 1

Microevolution is what:

Macroevolutions is what:

Answer 1

natural selection, change under species level

common descent, change occurs above species level

Question 2

What are some of darwins observations - part 1

Answer 2

• Members of a pop show variation in their traits
• traits inherited by offspring from parents
• populations support more offspring than the environment can support?
• inherited variations affect survival and reproduction

Question 3

What are some of darwins observations - part 2

Answer 3

• Inherited traits that increase survival and reproduction likely to leave more offspring than others
• Over generations this will lead to the accumulation of favorable characteristics

Question 4

Darwinian giraffes example?

Answer 4

Prerequisite: the neck length is a variable and inheritable trait

Question 5

Does natural selection select phenotypes or genotypes?

Answer 5

Phenotypes

Question 6

3 mechanisms act on variability

Answer 6

• Natural selection
• Genetic drift
• Gene flow (migration)

Question 7

Examples of selection

Answer 7

Antibiotic resistance, sickle cell anmea, virus mutations, dog breeds

Question 8

What is genetic drift?

Answer 8

Change in frequency of alleles, reduction in genetic variation.
Could be caused by bottleneck effect, like natural disaster
Or founder effect, many become isolated from main population, like Amish

Question 9

Effects of genetic drift?

Answer 9

• significant in small populations
• allele frequency change at random
• individual selection not based off phenotypes
• can lead to loss of genetic variation

Question 10

What is the ring of species effect

Answer 10

gene flow through species/ pop that cannot reproduce, geo isolation

Question 11

what is Introgression

Answer 11

Insertion of allele in one species, specific to another

Question 12

How is population defined?

Answer 12

Localised group of individuals that are capable of interbreeding and producing fertile offspring

Question 13

What is a genepool?

Answer 13

total aggregate of genes in a population at any 1 time

- consists of all loci in all individuals

Question 14

What is the hardy - weinberg theorem?

Answer 14

allels and genotype frequency in a pop will remain consistent from gen to gen in the absence of other evolutionary forces

Question 15

5 conditions for non- evolving pop

Answer 15

Large pop size, no genetic drift
No gene flow, no migration 
no mutations
random mating, no sexual selection 
no natural selection