selection and evolutionary change - 8.1

Question 1

artificial selection

Answer 1

occurring in captivity, individuals within a species are selected for breeding based on specific traits
eg. dog breeding

Question 2

natural selection (8.1 selection and evolutionary change)

Answer 2

individuals within a species will be better adapted, or have traits that are advantageous, that will allow them to survive to reproduce and pass on their genes
eg. darwin’s finches

Question 3

sexual selection

Answer 3

individuals within a population choose their mate based on particular traits - certain traits increase reproductive success
- female choosers and male competitors
- often leads to sexual dimorphism

Question 4

sexual dimorphism example

Answer 4

peacocks, males are brightly coloured and attractive while females are not

Question 5

patterns of selection definition

Answer 5

selective pressures, such as food, disease, predation, and climate, can result in changes to allele frequencies

Question 6

3 patterns of selection definition

Answer 6

stabilizing, directional, disruptive

Question 7

stabilizing selection definition

Answer 7

most common phenotype in an environment is favoured, variability decreases

Question 8

2 examples of stabilizing selection

Answer 8

medium bill length in hummingbirds
average birth weight in humans

Question 9

directional selection definition

Answer 9

favours a phenotype at one extreme
very common in artificial breeding

Question 10

directional selection examples

Answer 10

longer bill length in hummingbirds
longer necks in giraffes
colour change in peppered moths

Question 11

disruptive selection definition

Answer 11

favours phenotypes at both extremes
eliminates “average joe”

Question 12

disruptive selection examples

Answer 12

long and short bill length in hummingbirds
coho salmon- large and small are better at breeding

Question 13

3 ways evolutionary change can happen without selection

Answer 13

genetic drift
the founder effect
the bottleneck effect

Question 14

genetic drift definition

Answer 14

changes to allele frequencies that happen by chance and not due to selection
- in small populations, the frequencies of certain alleles can be changed by chance alone
- the new population lacks genetic diversity

Question 15

the founder effect definition

Answer 15

a small number of individuals from a population establish a new population
- a common allele can become uncommon or vice versa

Question 16

the bottleneck effect definition

Answer 16

a reduction in population size (which is sometimes temporary) often leads to a change in allele frequencies and a loss of genetic diversity

Question 17

the hardy-weinberg principle definition

Answer 17

in large populations in which only random chance is at work, allele frequencies are expected to remain constant from generation to generation

Question 18

2 important things to keep in mind about selection and evolutionary change

Answer 18

selection can act only on existing variation
individuals are selected, but populations evolve