selection and speciation

Question 1

describw what is meant by speciation (allopatric)

Answer 1

• geographical isolation
• separate gene pools/no interbreeding
• variation due to mutation
  -different selection pressures
• selection for advantageous allele
• dofferential reproductive success
• change in allelic frequencies

Question 2

describe the process of succession

Answer 2

• colonisation by pioneer species
• pioneers cause change in environmental a/biotic factors
• pioneers make environment less hostile for new species
• new species make conditions less suitable for previous species
• change in biodiversity
  -stability increases
• climax community

Question 3

causes of variation

Answer 3

• mutation
• meiosis
  -random fertilisation of gametes

Question 4

discontinuous variation

Answer 4

caused predominately by genetic factors
- produces categoric data
- single gene
eg: human blood groups

Question 5

climatic conditions

Answer 5

temp
light intensity
humidity

Question 6

continuous variation

Answer 6

• polygene (more than one gene)
  eg: height and mass
• normal distribution curve

Question 7

natural selection

Answer 7

individuals better adapted to environment
more likely to survive and reproduce
increasing allelic frequency of advantageous allele within popultion

Question 8

natural selection

Answer 8

variation due to mutation
differential survival: thoe with beneficial alelles more likely to survive and reproduce
selection pressure introduced
those with advantageous allele more likely to survive and reporduce
differential reproductive success
increase in allelic frequency
over many generations

Question 9

stabilising selection

Answer 9

• occurs when stable environment
  eg: baby birth mass weight
• selection pressure at both ends of distribution
• favours average, eliminates extremes. increases proportion of population that is well adapted to environment
• when SD decrease, mean unaltered
• reduces variability
• reduces opportunity for evolutionary change

Question 10

directional selection

Answer 10

• mean: optimum phenotype for existing conditions
• selection pressure introduced, favours new extreme phenotype
  eg: antibiotuic resistance

Question 11

disruptive selection

Answer 11

• selection pressure favours extreme phenotypes
• least common, most important in selection

Question 12

species

Answer 12

group of individuals with similar characteristics and same genes
capable of interbreeding to produce a fertile offspring
- same gene pool

Question 13

speciation

Answer 13

evolution of a new species from an existing species
must undergo:
- reproductive isolation (prevented period of interbreeding)
this will cause accumulation of mutations and different selection pressures

Question 14

hardy weinberg principle

Answer 14

allelic frequencies in a population will remain constant from one generation to the next, provided there is:
- random fertilisatioon of gametes
- no selection
- no migration
- no mutations
- a large population

Question 15

genetic drift/ bottleneck

Answer 15

random change in allelic frequencies
eg: natural disaster

Question 16

gene flow/ founder effect

Answer 16

change in allelic frequency due to the migration of fetile individuals
eg: migration

Question 17

allopatric speciation

Answer 17

physical barrier dividing a population (eg: river, mountain, road)
- geographically isolated
- different slection pressures
- mutations accumulate
- reproductively isolated (cant interbreed to form a fertile offspring)

Question 18

sympatric speciation

Answer 18

same area
become reproductively isolated for some reason (eg: choice of food/season to mate/active after hybernation)

Question 19

isolating mechanisms list

Answer 19

• allopatric
• sympatric
• temporal
• ecological
• behavioural
• mechanical
• gametic
• hybrid

Question 20

temporal isolation

Answer 20

breed at different times of the year

Question 21

ecological isolation

Answer 21

different habitats in the same area

Question 22

behavioural isolation

Answer 22

different behaviour patterns (ie: different courtship behaviour)

Question 23

mechanical isolation

Answer 23

anatomical differences making it impossible for gametes to come together

Question 24

gametic isolation

Answer 24

incompatibility between gametes prevent hybrid from forming (eg: sperm may be destroyed in vagina for females, too acidic)

Question 25

hybrid

Answer 25

organisms interbreed but offsprings are infertile
(eg: horse and donkey = mule)

Question 26

hybrid

Answer 26

organisms interbreed but offsprings are infertile
(eg: horse and donkey = mule)

Question 27

sympatric speciation process

Answer 27

• occurs within same habitat
• gene pools remain separate/ no gene flow
• different alleles are selected for/ change in frequency of alleles
• disruptive selection
• eventually species can not interbreed to produce a fertile offspring

Question 28

individuals in a populatuion shwo phenotypic variation. give two factors that cuase variation.

Answer 28

genetic crossing over
environmental factors

Question 29

what is allopatric speciation?

Answer 29

population separated into different geographical regions
- formation of new species from geographically isolated populations

Question 30

what is sympatric speciation?

Answer 30

formation of new species from existing species without geographical isolation