Speciation - other

Question 1

what is the founder effect?

Answer 1

smaller population has a reduced frequency of alleles compared to the original population; reduced genetic diversity.

Question 2

what is the bottleneck effect?

Answer 2

disaster such as a fire or flood etc, or a human destruction such as destroying habitats causing death and reduction in the frequency of alleles

Question 3

what is sympatric speciation?

Answer 3

come from the same geographical area, gene flow is prevented through genetic mutations which do not allow interbreeding between the two species

Question 4

what is allopatric speciation?

Answer 4

come from different geographical areas, gene flow is prevented due to physical barriers such as mountains, rivers etc

Question 5

what is polyploidy?

Answer 5

it is instant speciation

Question 6

is polyploidy rare or common?

Answer 6

rare in animals but common in plants

Question 7

what ability do polyploids have?

Answer 7

often have the ability to survive extreme conditions

Question 8

what form of speciation is polyploidy?

Answer 8

it is a form of sympatric speciation as it doesn’t involve a geographical barrier or form of isolation

Question 9

how does polyploidy occur?

Answer 9

sometimes during meiosis spindles cause the incorrect number of chromosomes to be pulled to the wrong end, resulting in gametes which have more or less chromosomes than normal. this process is called non-disjunction and may result in gametes which have 2n (not n).

Question 10

can polyploids reproduce?

Answer 10

under normal circumstances, any offspring of these gametes would be infertile, But if two 2n gametes fuse, a 4n (or tetraploid) is produced, which may be fertile.

Question 11

what are the two forms of polyploidy called?

Answer 11

autopolploidy and allopolyploidy

Question 12

what is autopolyploidy?

Answer 12

when all sets of chromosomes come form the same ancestral species. it occurs when sets of chromosomes fail to separate during meiosis

Question 13

what is allopolyploidy?

Answer 13

when the sets of chromosomes originate form two or more ancestral species

Question 14

what are the six types of pre-zygotic RIM’s?

Answer 14

1) geographical isolation
2) structural isolation
3) ecological isolation
4) temporal isolation
5) behavioural isolation
6) gametic isolation

Question 15

what is geographical isolation?

Answer 15

physical barriers such as mountains rivers and oceans. this causes the gene pool to become less varied.

Question 16

what is structural isolation?

Answer 16

differences in structure of the external reproductive organs not allowing for the transfer of sperm between the sexes

Question 17

what is ecological isolation?

Answer 17

differences in niches within the same geographical area. this means the species never come into contact with each other because they are not active at the same time, or they have different mating seasons, e.g. nocturnal, diurnal

Question 18

what is behavioural isolation?

Answer 18

differences in behaviour, typically mating behaviour such as courtship

Question 19

what is gametic isolation?

Answer 19

incompatibility of gametes due to biochemical differences preventing the zygote forming as the sperm/pollen is not attracted to chemicals produced by the egg

Question 20

despite the prezygotic rims, sperm may fertilise eggs of different species to form a ______

Answer 20

hybrid

Question 21

hybrids are usually prevented from doing what?

Answer 21

producing viable offspring

Question 22

what are the three types of postzygotic rims?

Answer 22

1) hybrid inviability
2) hybrid breakdown
3) hybrid sterility

Question 23

what is hybrid inviabilty?

Answer 23

the fertilised egg does not develop as the chromosomal incompatibility leads to developmental problems, resulting in a very low chance of the offspring surviving

Question 24

what is hybrid breakdown?

Answer 24

occurs when the hybrid reaches maturity and is able to breed but any generations after that are sterile

Question 25

what is hybrid sterility ?

Answer 25

where the hybrid reaches maturity, but is sterile so cannot breed

Question 26

what is convergent evolution?

Answer 26

occurs when two or more unrelated species evolve to develop similar adaptations as a result of being subject to similar selection pressures (factors which may reduce reproductive success)

Question 27

what type of structures does convergent evolution result in and what are they?

Answer 27

analogous structures. these are structures with different origins but have evolved to appear similar or have similar functions

Question 28

what is divergent evolution?

Answer 28

occurs when two or more speices arises from a common ancestor due to different ecological niches, usually by way of allopatric speciation.

Question 29

what type of structures does divergent evolution result in and what are they?

Answer 29

homologous structures. structures with same origins but have evolved different functions.

Question 30

what is adaptive radiation?

Answer 30

a type of divergent evolution in which organisms change rapidly from an ancestral species into an abundance of new forms.

Question 31

what is co-evolution and how does it occur?

Answer 31

where two species influence each other’s evolution. this is because each species exerts a selective pressure on the other species. Both of these species have a close ecological relationship.

Question 32

what is parallel evolution and why does it happen?

Answer 32

occurs when species share a common ancestor and evolve in similar ways independent of other species. this happens because of the two different species experiencing similar kinds of environmental pressures and survive only by undergoing similar adaptations.

Question 33

what is gradualism?

Answer 33

evolutionary process that proceeds slowly but continuously, and eventually the accumulation of changes result in speciation occuring

Question 34

what is punctuated equilibrium?

Answer 34

long periods of very little evolutionary change (stasis), interrupted by short, rapid bursts of rapid speciation, which may be triggered by environmental changes such as a bush fire or a rise in sea level.