Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

IB Biology > 10.3 Gene pools and speciation > Flashcards

10.3 Gene pools and speciation Flashcards

1
Q

What is a gene pool?

A

A gene pool represents the sum total of alleles for all genes present in a sexually reproducing population

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What does a large gene pool indicate?

A

High amounts of genetic diversity and increasing the chances of biological fitness and survival

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What does a small gene pool indicate?

A

Low amounts of genetic diversity and reducing biological fitness and increasing chances of extinction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What can gene pools be used to determine?

A

Allele frequency

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is allele frequency?

A

The proportion of a particular allele within a population

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What does evolution require to happen?

A

That allele frequencies change within the gene pool of the population to reflect the evolve characteristics

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is evolution?

A

The cumulative change in the heritable characteristics of a population across successive generations

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What are the five processes that can cause changes to allele frequency within a gene pool?

A

Mutation
Gene flow
Sexual reproduction
Genetic drift
Natural selection

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

How does mutation result in changes to allele frequency within a gene pool?

A

A random change in the genetic composition of an organism due to changes in the DNA base sequence

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

How does gene flow result in changes to allele frequency within a gene pool?

A

The movement of alleles into or out of a population as a result of immigration or emigration

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

How does sexual reproduction result in changes to allele frequency within a gene pool?

A

Sex can introduce new gene combinations and alter allele frequencies if mating is assortative

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

How does genetic drift result in changes to allele frequency within a gene pool?

A

The change in the composition of a gene pool as a result of a chance or random event

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

How does natural selection result in changes to allele frequency within a gene pool?

A

The change in the composition of a gene pool as a result of differentially selective environmental pressures

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is genetic drift?

A

The change in the composition of a gene pool as a result of chance or random event

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

When will genetic drift happen fastest and be most significant and why?

A

In smaller populations because chance events have a bigger impact on the gene pool

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What will be less affected by random events and maintain more stable allele frequencies with low genetic drift?

A

Larger populations

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

When will allele frequencies change significantly?

A

When a large population is reduced to a small population

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What are the two mechanisms when a large population is reduced to a small population?

A

Population bottlenecks and the founder effect

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

When do population bottlenecks occur?

A

When an event reduces population size by an order of magnitude

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What causes population bottleneck?

A

Natural occurrences or human induced

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What happens to the surviving population of population bottlenecks?

A

They will have less genetic variability than before and will be at a higher level of experiencing genetic drift

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What happens to the surviving species of population bottlenecks when they repopulate?

A

The newly developing gene pool will be divergent to the original

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

When does the founder effect occur?

A

When a small group breaks away from a larger population to colonise a new territory

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

How does the founder effect differ from population bottlenecks?

A

The original population remains largely intact

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Why is a smaller group in the founder effect subject to more genetic drift?
Because it does not have the same degree of diversity as a larger population
26
What happens to the smaller group in the founder effect when it increases in size?
Its gene pool will not be representative of the original gene pool anymore
27
What is the range of allele frequencies?
from 0 - 1.0
28
What can changes in allele frequencies reflect?
Either random processes or differential processes
29
When will the population bottlenecks and the founder effect exacerbate genetic differences?
Between geographically isolated populations
30
How do you compare allele frequencies?
1. go to the allele frequency database 2. type a gene name into the search parameter 3. choose a specific gene loci 4. Select a polymorphism 5. Choose a frequency display format
31
What is natural selection?
The change in the composition of a gene pool in response to a differentially selective environmental pressure
32
What is the frequency of one particular phenotype in relation to another the product of?
The type of selection that is occurring
33
What is a stabilising selection?
When a middle phenotype is favoured at the expense of both phenotypic extremes
34
What does stabilising selection result in?
The removal of extreme phenotypes
35
When does stabilising selection happen?
When environmental conditions are stable and competition is low
36
What is an example of stabilising selection?
Human birth weights
37
What is directional selection?
When one phenotypic extreme is selected at the cost of the other phenotypic extreme
38
What does directional selection result in?
The phenotypic distribution clearly shift in one direction to the beneficial extreme
39
When does directional selection happen?
In response to gradual or sustained changes in environmental conditions
40
What is directional selection typically followed by and when?
Stabilising selection once an optimal phenotype has been normalised
41
What is an example of directional selection?
The development of antibiotic resistance in bacterial populations
42
What is disruptive selection?
When both phenotypic extremes are favoured at the expense of the middle phenotypic ranges
43
What does disruptive selection cause?
The phenotypic distribution to deviate from the centre and results in a bimodal spread
44
When does disruptive selection happen?
When fluctuating environmental conditions favour the presence of two different phenotypes
45
What may happen if there is a continued separation of phenotypic variants in disruptive selection?
The population may split into two distinct sub populations
46
What is an example of disruptive selection?
The proliferation of black or white moths in regions of sharply contrasting colour extremes
47
When does reproductive isolation happen?
When barriers prevent two populations from interbreeding
48
What are the two main categories of reproductive isolation barriers?
Prezygotic isolation and postzygotic isolation
49
What is prezygotic isolation?
Occurs before fertilisation can occur so no offspring are produced
50
What is postzygotic isolation?
Occurs after fertilisation where offspring are either not viable of infertile
51
What are the different types of prezygotic isolation barriers?
Temporal Behavioural Geographical/Ecological Mechanical
52
What are the different types of postzygotic isolation barriers?
Inviability Infertility breakdown of hybrid organisms
53
When does temporal isolation occur?
When two populations differ in their periods of activity or reproductive cycles
54
What is an example of temporal isolation?
Leopard frogs and wood frogs sexually mature at different times in the spring and thus cannot interbreed
55
When does behavioural isolation occur?
When two populations exhibit different specific courtship patterns
56
What is an example of behavioural isolation?
Certain populations of cricket may be physically the same but only respond to specific mating songs
57
When does geographic isolation occur?
When two populations occupy different habitats or separate niches within a common region
58
What is an example of geographic isolation?
Lions and tigers occupy different habitats and do not interbreed
59
What is hybrid inviability?
When hybrids are produced but fail to develop to reproductive maturity
60
What is hybrid infertility?
Hybrids fail to produce functional gametes
61
What is hybrid breakdown?
F1 hybrids are fertile but F2 generation fails to develop properly
62
What is speciation?
An evolutionary process that results in the formation of a new species from a pre existing species
63
When does speciation occur?
When reproductive isolating mechanisms prevent two breeding organisms from producing fertile viable offspring
64
What are the two ways speciation can occur?
Allopatric and sympatric speciation
65
When does allopatric speciation occur?
When a geographical barrier physically isolates populations of an ancestral species
66
What are the reasons two populations begin to evolve in allopatric speciation?
Cumulative mutation Genetic drift Natural selection
67
What eventually happens in allopatric speciation?
The two populations reach a degree of genetic divergence where they can no longer interbreed
68
What is sympatric speciation?
The divergence of species within the same geographical location
69
What can cause sympatric speciation?
The reproductive isolation of two populations as a result of genetic abnormalities
70
What error typically arises during sympatric speciation and what does that cause?
A chromosomal error may arise which prevents successful reproduction with any organism lacking the same error
71
Structurally, what can cause speciation?
A meiotic failure during gamete formation
72
What happens if meiotic cells fail to undergo cytokinesis?
Chromosomal number will double in the gamete
73
What is the result of offspring where the chromosomal number is double in the gamete?
Offspring with additional sets of chromosomes
74
How can polyploid offspring cause speciation?
If the offspring are viable and fertile but cannot interbreed with the original parent population
75
What do fertile polyploid offspring typically require?
Two polyploid parents
76
Why do fertile polyploid offspring need two polyploid parents?
Because reproduction with an the original parent population results in offspring with an uneven number of chromosome sets
77
Where is polyploidy more common and why?
Plant species as they lack separate sexes and can reproduce asexually
78
Can infertile polyploids still reproduce asexually?
Yes via vegetative propagation
79
Why do farmers develop polyploid crops? (two reasons)
Allows for the production of seedless fruits Polyploid crops grow larger and demonstrate improved longevity and disease resistance
80
How can farmers induce polyploidy in certain plant species?
By treating plants with certain drugs
81
What is the genus allium comprised of?
Monocotyledonous flowering plants like onions, garlic, chives and leeks
82
What has happened in the allium species?
Polyploidy resulting in reproductively isolated populations with distinct phenotypes
83
What are the two ways evolution can occur?
Microevolution and macroevolution
84
What is microevolution?
Within a species
85
What is macroevolution?
Across the species barrier
86
What are the two ways evolution via speciation may occur?
Phyletic gradualism or punctuated equilibrium
87
What is the phyletic gradualism model?
Speciation occurs uniformly via the steady and gradual transformation of whole lineages
88
What supports phyletic gradualism?
The fossil record of the horse as many middle forms connect to the modern equivalent
89
In accordance to phyletic gradualism what type of process is speciation viewed as?
A smooth and continuous process
90
What is the punctuated equilibrium model?
Species remain stable for long periods before undergoing abrupt and rapid change
91
What type of process is speciation according to punctuated equilibrium?
A periodic process where big changes happen suddenly followed by long periods of no change
92
What evidence supports the punctuated equilibrium model?
The general lack of transitional fossils for most species
93
Apart from punctuated equilibrium what else can explain the lack of traditional fossils?
The rare and irregular conditions needed for fossilisation

IB Biology (57 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions