speciation and artificial selection

Question 1

define artificial selection

Answer 1

selection of plants or animals with desirable characteristics for breeding - aka selective breeding

Question 2

what creates selection pressure in natural selection

Answer 2

nature

Question 3

what creates selection pressure in artificial selection

Answer 3

humans breeding the organisms

Question 4

describe selection

Answer 4

choosing 2 of the same species which show desirable traits
- eg. milk yield

Question 5

describe interbreeding

Answer 5

choosing the organisms that show the best/desirable traits and breeding them together

Question 6

what is speciation

Answer 6

formation of a new species through evolution

Question 7

state the 5 steps of artificial selection

Answer 7

• selection
• interbreed
• inbreed
• repeat
• change in frequency

Question 8

describe some of the problems caused by inbreeding (3)

Answer 8

• limiting gene pool and genetic diversity reduces the ability of inbred organisms to adapt to environmental change
• closely related organisms are likely to have same recessive alleles so offspring are more likely to be homozygous for recessive traits for genetic disorders
• reduces ability to survive and reproduce so are less biologically fit

Question 9

what is allopatric speciation

Answer 9

when some individuals are separated from the rest of a population by physical barriers
- eg. sea, desert, mountain range

Question 10

why are there different physical adaptations for organisms in allopatric speciation

Answer 10

• environments are different
• so selection pressures different
• so physical adaptations different

Question 11

what is sympatric speciation

Answer 11

when members of two different species interbreed and form fertile offspring - new hybrid is formed

Question 12

what do prezygotic reproductive barriers do

Answer 12

prevent fertilisation and zygote formation

Question 13

what do postzygotic reproductive barriers do

Answer 13

reduce viability of reproductive offspring potential

Question 14

what is a gene bank

Answer 14

stores biological samples
- eg. sperm and eggs or seeds

Question 15

what is outbreeding

Answer 15

breeding unrelated or distantly related varieties

Question 16

define isolating mechanisms

Answer 16

ways in which organisms become isolated from each other with no gene flow, in order to form new species

Question 17

define isolation

Answer 17

separation of members of a species so there is no gene flow

Question 18

why can an isolated species no longer produce fertile offspring?

Answer 18

• as phenotypes have been changing, DNA has been changing
• new alleles/genes/chromosomes
• cannot produce viable gametes through meiosis

Question 19

define total reproductive isolation

Answer 19

reproducing isolated species together but they will no produce fertile offspring

Question 20

define temporal isolating mechanism

Question 21

define ecological isolating mechanism

Question 22

define behavioural isolating mechanism

Question 23

define mechanical isolating mechanism

Question 24

define genetic drift

Answer 24

changes in allele frequency within a population between generations

Question 25

the ….. a population, the ….. the impact allele frequency changes have

Answer 25

smaller
bigger

Question 26

evolution occurs more … in …. populations

Answer 26

rapidly
smaller

Question 27

define genetic bottleneck

Answer 27

caused by events that kill almost all of a population - results in small gene pool

Question 28

what is the result of genetic bottleneck

Answer 28

lack of genetic diversity + genetic diseases that exist are more likely to be passed on

Question 29

define founder effect

Answer 29

when a few individuals from an existing population relocate to an isolated area

Question 30

what is the result of the founder effect?

Answer 30

small population breeding together and therefore smaller gene pool

Question 31

define natural selection

Answer 31

where individuals with advantageous traits are more likely to survive and reproduce, passing on those traits to their offspring