Evolution and Speciation

Question 1

What is microevolution?

Answer 1

How species change over times

Question 2

What is macroevolution?

Answer 2

How new species arise?

Question 3

What is the biological species concept?

Answer 3

Groups of actually or potentially interbreeding populations which are reproductively isolated from other such groups

Question 4

What are the limitations of the biological species concept?

Answer 4

Is a higher organism targeted theory - only applies to sexually mating organisms

Question 5

What is introgression?

Answer 5

A gene can move from the gene pool of one species to the gene pool of another (usually geographically close)

Question 6

What is the initial event to give rise to a new species?

Answer 6

the generation of barriers to gene flow within a species

Question 7

What is allopatric speciation?

Answer 7

when a population becomes geographically separated

Question 8

What is sympatric speciation?

Answer 8

Barriers arise to gene flow without geographical separation

Question 9

What is parapatric speciation?

Answer 9

When adjacent subpopulations have limited contact

Question 10

What is the problem with the three main models of speciation?

Answer 10

Although the circumstances might exist now, it is hard to tell which factor was actually the causative agent of speciation

Question 11

What are the two reproductively isolating mechanism in a population which has genetically diverged?

Answer 11

Pre Zygotic and Post Zygotic isolation

Question 12

What is the Dobzhansky Muller theory?

Answer 12

That reproductive isolation involves interactions at multiple gene loci

Question 13

What genetic manipulation can be used to prove the Dobzhansky Muller theory?

Answer 13

The use of x linked chromosomes in drosophila

Question 14

What is Haldane’s Rule?

Answer 14

Hybrid sterility or inviability effects are greater in the heterozygotic sex

Question 15

How does a series of inversion in a balancer chromosome prevent recombinants?

Answer 15

The series of inversions prevent synapsis of adjacent chromosomes.
If crossovers were to occur, the recombinants would produce aneuploid gametes which are inviable (from acentric and dicentric chromosomes)

Question 16

How can you identify if progeny contain the balancer chromosome in a screen?

Answer 16

From the dominant visible marker allele

Question 17

How can you ensure a member of the population does not contain two balancer chromosomes?

Answer 17

They carry a recessive lethal mutation

Question 18

What is the mathematical theory behind snowball speciation

Answer 18

Quadratic increases of new allele interactions between species

Question 19

How is chromosomal rearrangement different to balancer chromosomes?

Answer 19

It is a naturally occurring phenomenon unlike balancer chromosomes which are genetically engineered

Question 20

Where are you likely to find chromosome rearrangements?

Answer 20

In closely related species which are growing in different populations

Question 21

What is the difference between intrinsic and extrinsic hybrid sterility?

Answer 21

Intrinsic sterility does not rely on environmental factors whereas extrinsic does

Question 22

What specific category of reproductive isolation does pollination by different insects fall into?

Answer 22

Ecological prezygotic isolation

Question 23

Why might selection favour prezygotic isolation to postzygotic isolation? (assuming no geographical barriers exist)

Answer 23

It would save ‘cost’ for the species to have prezygotic mechanisms in place = REINFORCEMENT

Question 24

What is a heterogenous habitat?

Answer 24

A habitat which is not geographically separated but patches of the habitat offer different selective pressures

Question 25

What is an example of an organism that underwent sympatric speciation (presumed)

Answer 25

The American hawfly

Question 26

What is the idea of group selection in sexual mating?

Answer 26

The idea of viewing the benefit of the potential mate on the whole group rather than the individual

Question 27

What is runaway sexual selection theory?

Answer 27

That female choice of mate drives the evolution of a particular phenotype past the point at which it is increasing their (and potential offspring) chance of survival

Question 28

What is Handicap theory?

Answer 28

Suggests that a particular phenotype can demonstrate a large obvious handicap to an individual - and their survival to adulthood must mean that they have otherwise perfect genotypes