Evolution & Speciation

Question 1

Ageing

Answer 1

Change in individual over time

Question 2

Metabolism

Answer 2

Organism changing the environment

Question 3

Evolution

Answer 3

Permanence change in a population over time, due to external pressures and random genetic mutations. These changes may not be observable from one generation to the next but the process over time will cause visible change to the species.

Question 4

Lamarcks Theory

Answer 4

“Use and disuse, life evolves as environments change” Certain organs and traits can be “developed” as a result of an environmental need (selection pressure) as they are used more often and therefore are more developed. The more developed organs will be inherited by offspring and thus a species will evolve. Individuals therefore lose characteristics they do not require, or use.

Question 5

Giraffe Example (Lamarck)

Answer 5

Giraffes stretch their neck to reach food high in trees - this strengthens and lengthens the neck and is passed on to offspring.

Question 6

Darwins Decent with Modification

Answer 6

Individuals in a population vary in their heritable characteristics - some of which are more suited to the environment and are therefore selected for, and give rise to visible change in the species as a whole.

Question 7

Natural Selection

Answer 7

Environmental pressures give advantage to certain traits - therefore some individuals within the population are more likely to survive and pass on their genes - causing the species to change and evolve over time

Question 8

Four basic principles of evolution by natural selection

Answer 8

1. Individuals are not identical
2. Some of the variation between individuals is heritable
3. All populations are cabale of exponential growth but have limited resources… therefore….
4. Variations that increase survival and reproductive success are more likely to be passed down to others

Therefore…..
The heritable features that define a population will change over time.

Question 9

Speciation

Answer 9

Formation of new and distinct species by splitting a single lineage into two or more genetically seperate ones

Question 10

What drives speciation

Answer 10

• Barrier formed
• New Habitat
• Genetic Change

Question 11

Allopatric Speciation

Answer 11

Formation of species that are geographically isolated from one another ( Selection pressures are slightly different and mutations aren’t being transferred within the two groups, thus speciation occurs. )

Question 12

Peripatric Speciation

Answer 12

small groups of individuals break off from the larger group and form a new species

Question 13

Parapatric Speciation

Answer 13

Species spread out over a large area and individuals only mate with those in their own geographic region - various niches within the same habitat

Question 14

Sympatric Speciation

Answer 14

No physical barriers & close proximity BUT a new species spontaneously develops through genetic change

Question 15

Herbert Spencer described evolution as …

Answer 15

Survival of the fittest

Question 16

Herbert spencer definition of fitness

Answer 16

The contribution made to a population of descendants by an individual relative to the contribution made by others in its present population. (all about relativity)

Question 17

Selection Pressure

Answer 17

Evolutionary force that causes a particular phenotype to be more favourable in certain environmental conditions - considered the driving force of evolution via natural selection

Question 18

How do selection pressures have such an effect over a short period of time?

Answer 18

Their ability to vary and change DNA within a population can happen rapidly due to high reproduction rates and very large population sizes.

Question 19

2 key points of antibiotic resistance

Answer 19

• Natural selection is a process of editing rather than creating
• Natural selection depends on time and place

Question 20

Mutation

Answer 20

Permanent change to the base code of DNA

Question 21

Gametic cell

Answer 21

Gametes - involved in sexual reproduction

Question 22

Somatic cell

Answer 22

Not involved in reproduction - any mutations to these cells CAN NOT be passed fown

Question 23

Effect of mutation

Answer 23

• Some result in no change, others cause a functional change (+/-) and rarely, they are fatal.

Question 24

Rates of mutation (mammals compared to bacteria)

Answer 24

Estimated mutation rate in all species is 1 per 100,000 genes per generation. - therefore rate of reproduction significantly influences rate of mutation. Mammals have much slower rates of mutation compared to bacteria - which mutate fast thereby evolve quickly

Question 25

Is evolution goal oriented

Answer 25

No, evolution does not aim to achieve a specific outcome.

Question 26

Genetic Drift

Answer 26

Unpredictable fluctuations in allele frequency from one generation to the next - smaller populations are more vulnerable_

Question 27

Genetic Drift result

Answer 27

Loss of certain alleles/alter the allele frequency, a small subset of survivors are left to rebuild the entire population therefore their alleles become dominating.

Question 28

Intersexual Selection

Answer 28

Form of natural selection in which individuals of one sex (usually females) are choosy in selecting their mate of the other sex. Also known as mate selection (higher genetic fitness of offspring)

Question 29

Intrasexual Selection

Answer 29

Form of natural selection in which their is competition amongst one group of the same sex (males) for mates of the opposite sex (responsible for the formation for deer horns etc)

Question 30

Coevolution

Answer 30

Changes in at least two species genetic compositions that reciprocally affect each others evolution

Question 31

Light zone in germinal centre

Answer 31

B-Cells proliferate and activate

Question 32

Dark zone in germinal centre

Answer 32

B cells start adding point mutations - small changes

Question 33

Antibiotic resistance

Answer 33

Bacteria's ability to vary and change their DNA within a population can happen rapidly due to high reproduction rates and very large population sizes. When a person is infected with staph, there may be a few bacteria that are drug resistant by chance. Over time, the population can become resistant as those that aren't die off and the drug resistant staph survive, reproduce and descendants inherent drug resistance.

Question 34

Evolution in germinal center

Answer 34

Once b cells add the point mutations, they go into the light zone and compete. Each B-cell has lsightly different antibodies (due to mutation) and those that are stronger survive, and the weaker ones die. = antibodies get better and stronger over time, allowing us to develop a better antibody to fight the infection.

Question 35

Are mutations directed

Answer 35

NO - Mutations are NOT directed. They are simply random but may OR MAY NOT bring advantage when that pressure is there. Without a selection pressure the mutation means nothing.

Question 36

Species

Answer 36

a group of populations who's members have the potential to interbreed and produce viable fertile offspring.