SPECIATION, INTERRUPTION OF GENE FLOW

Question 1

what is a species

Answer 1

a species is a group of organisms which are sufficiently closely related that they can interbreed and produce fertile offspring.
Share a common gene pool.

Question 2

what is evolution dependent on

Answer 2

evolution is dependent upon changes in the gene pool.

• mutation
• natural selection
• gene migration ( new alleles being added to
  population)
• non random mating ( increase homozygotic
  character)
• Genetic drift

Question 3

define speciation

Answer 3

speciation is the name given to a new species.

Question 4

define evolution

Answer 4

evolution is the mechanism how speciation is brought about.

Question 5

Isolating mechanisms

Answer 5

• geographical barrier e.g seas/oceans, mountains, rivers, desert.
• Ecological barriers e.g change in temperature , pH, humidity.
• Reproductive barriers e.g different breeding season, no stimulation from courtship, failure of polluation.

Question 6

process

Answer 6

• when populations are isolated there is no interchange of genes between groups.
• Mutations and natural selection can therefore differ in groups.
• over a long period of time they evolve into into different species that can no longer interbreed and produce fertile offspring.

Question 7

endemic

Answer 7

when a species is only found in certain areas they are called endemic to the region. There are many endemic species of plant & animal found in the Scottish islands.

Question 8

endemic examples

Answer 8

Rowen Tree is endemic all over europe however only one species is found on the isle of arran.

Wren has various sub species that are different from the mainland wren found in st kilda and outer Hebrides.

Question 9

interruption of gene flow

Answer 9

several populations in an area, however can only interbreed with immediate neighbours.
If only one of the population disappear the gene flow would be interrupted.

Question 10

continental drift

Answer 10

worlds land mass can be spilt into 6 distinct regions based on flara & fawna.

1 - Europe
2 - North America
3 - Africa
4 - Asia
5 - South America
6 - Australia

1 & 2 have similar animals
3,4,5 are quite different
6 has very different animals

Question 11

Adaptive radiation

Answer 11

the evolution of a different species from a common ancestor.
Ecological niche which is the ideal environment for a particular species.

Question 12

Darwins finches

Answer 12

Darwin noticed the finches differed greatly in beak size & shape, each one adopted to eat a particular food source.

same has occurred in the species of fish - chichlids buttercups and marsupiels.

Question 13

homology

Answer 13

homologous structures have the same common ancestor.

Question 14

Divergent Evolution

Answer 14

All mammals posses a pentadactyl limb.
- This has become adapted overtime to suit different functions. This is known as divergent evolution.

Question 15

convergent evolution

Answer 15

some animals posses similar structures but have adapted from different evolutionary origins.
This adaption is the coincidence of occupying similar ecological niches.
This is known as convergent evolution.