18.5- Isolation and speciation

?
  • Created by: Megan2413
  • Created on: 13-03-18 21:24
What is allelic frequency?
The number of times an allele occurs within the gene pool
1 of 19
As allelic frequency is affected by selection, what is it ultimately affected by?
Changes in envronmental conditions
2 of 19
What is evolution by natural selection?
A change in the allelic frequency within a population
3 of 19
What is speciation?
The evolution of a new species from an existing species
4 of 19
What three things make several individuals belong to the same species?
- common ancestry - sharing the same genes but not necessarily the same alleles - can interbreed to produce fertile offspring
5 of 19
How does adaptive radiation occur?
- when a population becomes separated, the environmental conditions in each area may vary causing different selection pressures, leading to natural selection - this changes allelic frequencies as each population becomes adapted to its new -->
6 of 19
conditions - the populations are now unable to interbreed
-->
7 of 19
Explain what genetic drift is
When there is not an equal chance of each allele being passed on due to a small population having a smaller variety of alleles hence lower diersity- those that are passed on will affect the population quickly
8 of 19
What is the difference between allopatric and sympatric speciation?
Allopatric speciation occurs due to a population becoming geologically separated whereas in sympatric speciation a population becomes ecologically separated
9 of 19
What is geographical separation?
When populations become isolated due to a physical barrier (e.g. oceans, mountain ranges, rivers..)
10 of 19
Could an ocean serve as geographical separation for any species?
No
11 of 19
How does allopatric speciation occur?
- A population becomes geographically separated forming two populations - environmental conditions may be different either side of the barrier - each population may have different selection pressures - each population will evolve to its local -->
12 of 19
conditions - ultimately may lead to reproductive separation and the formation of a separate species
-->
13 of 19
What is ecological separation?
When populations inhabit different habitats within tthe same area and so individuals rarely meet
14 of 19
What is temporal variation?
When the breeding seasons of each population don't coincide so they don't interbreed
15 of 19
What is behavioural variation?
When a mutation may affect the sequence or recognition of courtship behaviour which may prevent mating
16 of 19
What is mechanical variation?
Anatomical differences which may prevent mating to be physcially possible between two populations
17 of 19
What is gametic variation?
When gametes may be prevented from meeting due to genetic or biochemical incompatibility
18 of 19
When hybrids formed from the fusion of gametes from different species are sterile because they cannot produce viable gametes- what type of variation is this?
Hybrid sterility variation
19 of 19

Other cards in this set

Card 2

Front

As allelic frequency is affected by selection, what is it ultimately affected by?

Back

Changes in envronmental conditions

Card 3

Front

What is evolution by natural selection?

Back

Preview of the front of card 3

Card 4

Front

What is speciation?

Back

Preview of the front of card 4

Card 5

Front

What three things make several individuals belong to the same species?

Back

Preview of the front of card 5
View more cards

Comments

No comments have yet been made

Similar Biology resources:

See all Biology resources »See all Populations and evolution resources »