Chapter 11 - Evolution

Question 1

Answering natural selection questions.

Answer 1

1. ) Variation - “what is it”
2. ) Selection pressure - “what is it”
3. ) Who selected for/ Who selected against
4. ) Selected for survival + reproduce and pass on gene for
5. )Population is made up of

Question 2

Allopatric Speciation

Answer 2

1. ) population is spread across a geographical range
2. ) Population geographically isolated, resulting in reproductive isolation and the ceasing of gene flow.
3. ) Unique/different selection pressure act on different populations.
4. ) When populations are lated reintroduced to each other they cannot reproduce and create viable, fertile offspring.

Question 3

Species Vs Sub-species

Answer 3

Species: Cannot mate under any circumstances and produce viable, fertile offspring.
Sub-species: Under normal circumstances will not interbreed but have the capacity to do so.

Question 4

Polyploidy role in speciation

Answer 4

A plants gametes mutate so offspring are polyploidy, thus reproductively isolating them from the parent species who posses different number of chromosomes.

Question 5

Stabilising Selection:*

Answer 5

Extreme variations selected against, middle range, common phenotypes elected for.
reduced genetic diversity

Question 6

Directional Selection;

Answer 6

Shifts overall makeup of a population favouring 1 extreme variation.
Does not necessarily impact genetic diversity

Question 7

Disruptive/diversifying selection:

Answer 7

Favours two phenotype extremes at the expense of the intermediate.
Genetic diversity increases

Question 8

Advantage of Heterozygotes:

Answer 8

The combination of both alleles in the (co dominant) phenotype gives the individual the survival advantage when there are two or more selection pressures acting on the gene. Example of balanced polymorphism.
Eg.) Sickle cell anaemia
Sickle cell homo = no malaria, little oxygen
Normal = normal O2, malaria
Hetero = sufficient O2 (bit less), greatly reduced chance of malaria

Question 9

Differential Reproduction:

Answer 9

Organisms better adapted to the environment will tend to live longer and thus have the chance to produce more offspring.

Question 10

Gene Pool:

Answer 10

All genes and alleles present in a population

Question 11

Allele frequency

Answer 11

The rate of occurrence of a particular allele in a population/gene pool

Question 12

Gene Flow

Answer 12

Movement of genes/alleles between populations due to movement of individuals in and out of a population

Question 13

Genetic Drift

Answer 13

The change of allele frequency within a population due to a chance event

Question 14

Sources Of Genetic Variation:

Answer 14

Sexual reproduction; 
- Independent assortment
- Crossing over
- Random mating
Gene & Chromosomal Mutations:
Human Intervention:
- Cloning, genetic engineering ect...

Question 15

Cline variatrion:

Answer 15

A trait which gradually changes across geographic range.

Eg.) West –> East = Caucasian —> asian

Question 16

monomorphic variation:

Answer 16

Population show no variation in regard to a trait.

Eg.) all human bippedal

Question 17

Polymorphic variation:

Discontinuous Vs Continuous:

Answer 17

Polymorphic: Significant variation exists
Discontinuous: Population organised into discrete categories
continuous: Result of polygenic inheritance and is the continuous range of variety in regards to a trait.

Question 18

Evolutionary rate: Gradualism Vs Punctuated equilibrium

Answer 18

Gradualism: Species are slowly and gradually changing in response to different selection pressures and slowly diverge apart
Punctuated equilibrium: Divergent evolution where species stay the same for long periods (statis) and then have short bursts of rapid evolution that produce new species.

Question 19

Adaptive radiation

Answer 19

The proccess whereby a recent common anscestor diversifies rapidly into multiple new forms in response to selection pressures.

Question 20

Bottleneck effect:

Answer 20

Consequence of massive chance event and results in the significant reduction of population to the few who possess the necessary alleles for survival.
Decrease variation of gene pool

Question 21

Founder effect:

Answer 21

The colonisation of an isolated area by a small not genetically diverse population from a parent population.
Results in little genetic variation in isolated population

Question 22

divergent evolution:

Answer 22

Organisms with common ancestor develop different adaptations in response to selection pressures.

Question 23

convergent evolution:

Answer 23

Two unrelated species develop similar features and adaptations which aid survival in similar habitats.

Question 24

co-evolution

Answer 24

Two or more species effect each others evolution, and who continuously evolve at least in part in relation to each other.

Question 25

Parallel Evolution

Answer 25

two unrelated species diverge from a common ancestor and independently acquire similar features not present in the common ancestor.

Question 26

Overproduction concept of darwinism

Answer 26

Species produce more young than will survive to reproduction. Thus ‘unfit’ organisms will most likely die leaving the ‘fit’ to reproduce.

Question 27

Subspecies definition

Answer 27

Animals which possess distinct genetic variation and are reproductively isolated under normal circumstances but have the capacity to interbreed and produce viable, fertile offspring in captivity.