Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Biology 101 > Genetic Variation (PP17) > Flashcards

Genetic Variation (PP17) Flashcards

You may prefer our related Brainscape-certified flashcards:
Biology 101 flashcards Physics 101 flashcards Psychology 101 flashcards Chemistry 101 flashcards AP® Biology flashcards Organic Chemistry 101 flashcards Sociology 101 flashcards
1
Q

explain Quantitative characters:

A

vary along a continuum / spectrum within a population

Usually due to polygenic inheritance (additive effects of 2 or more genes influence single phenotypic character)

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

explain Discrete characters:

A

generally an either-or

Usually determined by a single locus with different alleles with distinct impacts on the phenotype

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

explain polymorphism

A

When 2 or more discrete characters are present & noticeable within a population

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

polymorphism applies to what characters?

A

Applies only to discrete characters, not quantitative characters

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

what are contrasting forms called?`

A

morphs

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

give an example of morphs

A

Red-flowered & white-flowered morphs in a wildflower population, or butterflies

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

are humans polymorphic

A

YES
Human populations are polymorphic for a variety of physical (e.g. freckles) & biochemical (e.g. blood types) characters

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

what does gene diversity measure

A

Gene diversity: measures average % of gene loci that are heterozygous

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

what does nucleotide diversity measure

A

Nucleotide diversity: measures the level of difference in nucleotide sequences (base pair differences) among individuals in a population

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

what do population genecists measure

A

Population geneticists measure genetic variation both at the level of whole genes & at the molecular level of DNA

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

do Humans have relatively little or a lot genetic variation compared to many other organisms

A

a little

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

What equation shows Evolution of a population can be explained as changes in allelic frequencies over time

A

Hardy-Weinberg Equilibrium
If certain conditions are met, allelic (genotypic) frequencies will not change

Genetic frequencies will stabilise to certain proportion:
p2 2pq q2

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

What conditions does the hardy-weinberg equilibrium need to met.

A 
Large population
No mutation (no new alleles)
No migration (isolated)
No natural selection
No sexual selection (random mating)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What happens when all conditions of hardy-weinberg met?

A

If all of these conditions are met, then we arrive at HW equilibrium:

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

can a population be in HW equilibrium for 1 locus but not others?

A

yes

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

what are genetic frequencies determined by?

A

Allelic frequencies

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

LOOK AT SLIDES FOR HARDY WEINBERG EQUATION

A

LOOK AT SLIDES

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

explain fitness

A

fitness = reproductive success of a genotype; generally we think of relative fitness (how well a certain genotype does compared to other genotypes in the same population)

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

fitness equation

A

LOOK AT SLIDES

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

What does the most prolific genotype mean and what fitness (W) does it have?

A

Most prolific genotype means the one that produces the most offspring

Most prolific genotype is considered to have fitness (W) of 1

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

what are the two ways of genetic variation

A

Mutations

-allele resorting

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

how do you get new alleles

A

due to changes in nucleotide bases

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

true or false: Mutations are Continuous, spontaneous, unpredictable, but inducible

-ONly Mutations that are present in gametes will be passed on

A

true

true

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

name the ways of allele resorting

A
  • Sexual reproduction (two different parents)
  • Segregation of alleles from different parents into different gametes
  • Crossing-over
  • Random fertilization
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

explain macroevolution

A

Large-scale changes in organisms (obvious differences in traits)
These changes are observable only after many generations

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

explain microevolution

A

Generation-to-generation change in allele frequency in a population
Generally fairly subtle changes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

what is one difference between macro and micro evolution and one similarity?

A

DIFFERENCE:
Examination of the same process at different scales

SIMILAR:
Both are due to non-random selection of random variation

28
Q

what are the 4 definitions of a species

A

Biological Species Concept:

Morphospecies Concept:
Ecological Species Concept:

Phylogenetic Species Concept:

29
Q

explain biological species concept and why would the definition not be true?

A
  • Organisms considered to be of same species if they can produce viable & fertile offspring
  • because of two barriers: PostZygotic and PreZygotic
30
Q

Explain Prezygotic Barrier

A

Pre-zygotic: before a sperm and egg cell even get the chance to fuse
“Causes for reproductive isolation”

31
Q

explain Post zygotic barrier

A

Post-zygotic: diploid cell is created, but fail to produce an organism that meets the definition of a species according to the above definition

32
Q

explain the morphospecies concept

A

Different species will look different - based on the morphology (physical characteristics)

33
Q

explain ecological species concept

A

Species defined based on role within ecosystem - each species will have a distinct role (“niche”)

34
Q

explain the phylogenetic species concept

A

Species determined by proximity / grouping on a phylogenetic tree - if grouped together, considered the same species.

35
Q

what are the prezygotic factors

A

Behavioural Isolation: 1 organism has a mating ritual that does not appeal to another (e.g. specific songs or “dances”)

Mechanical Isolation: Reproductive organs of the 2 organisms do not properly interact to allow fertilization

Temporal Isolation: 2 organisms are not active at the same time of day (e.g. nocturnal vs. diurnal)

Habitat / Ecological Isolation: 2 organisms live in different habitats / regions & so do not have exposure to one another

Gametic Isolation: Gametes of the organisms fail to fuse to form a zygote (usually due to differences in # chromosomes)

36
Q

what are the post zygotic factors (ie. why they can reproduce)

A

Reduced Hybrid Viability: Hybrid is not as physically fit as either parents (has a higher risk of disease or malformations, or is mal-adapted)

Reduced Hybrid Fertility: Hybrid is sterile & cannot pass on its genes (e.g. mules)

Hybrid Breakdown: F1 hybrid generation is viable & fertile but the F2 generation shows decreased viability & fertility

37
Q

what are the two types of speciation

A

Allopatric speciation

Sympatric speciation

38
Q

explain allopatric speciation

A

Due to geographical barrier that splits apart population of a common species
Create reproductive barrier that causes both populations to adapt differently
After many, many generations, this will ultimately lead to the differentiation of two distinct species that cannot interbreed
e.g. continental drift, highways

39
Q

explain sympatric speciation

A

Sympatric speciation: Any speciation not due to geographical barrier
Some other event / series of events causes a divergence
e.g. disruptive selection (if open a new niche, mate discrimination)

40
Q

What are the 5 factors that determine Allele frequencies

A 
Mutation
Genetic Drift
Gene Flow
Sexual Selection
Natural Selection
41
Q

explain genetic drift

A

Change in gene pool due to chance; result of random events / changes that cause allele frequencies to change

Can end up getting rid of beneficial, harmful, or neutral alleles (because it’s chance)

Can occur in small, unrepresentative populations

Can lead to decreased genetic variation within a population (but increases differences between populations)

42
Q

what are the two important mechanisms in genetic drift

A

2 important mechanisms:
Bottleneck effect
Founder effect

43
Q

explain the bottleneck effect

SEE DIAGRAM IN SLIDES

A

Occurs when an event causes only a small fraction of a population to survive (catastrophe, disease, food shortage, habitat loss, etc.)

Since population is small, it’s possible (nay, likely) that there’s imbalanced representation of alleles from the original population

Less-frequent alleles may no longer exist (if no carriers present in new population)

44
Q

give examples of bottle neck effect

A

insect survival through the winter, at-risk/endangered species (Florida Panther)

45
Q

explain the founder effect

A

Occurs when very few individuals from larger population establish a new colony

Bring only small sample of original genetic diversity

New population has only the alleles brought by the founders (less diverse than original population)

46
Q

give example of founder effect

A

Prevalence of Huntington’s disease amongst Afrikaners (South Africa) due to presence of disease in small population of Dutch settlers

47
Q

explain gene flow

A

Exchange of alleles due to migration between populations
Interactions within metapopulation

Reduce differences between populations that might have arisen through genetic drift / selection

Can transfer alleles that improve ability of population to adapt to local conditions

48
Q

does gene flow reduce or increase the differences between population

A

reduces

49
Q

give an example of gene flow

A

Spread of insecticide resistance amongst various mosquito populations

50
Q

what does sexual selection cause and what does that mean

A

sexual dimorphism (difference between the sexes )

51
Q

explain mate choice

A

Mate choice: (generally selection by females): may be at odds with other selective pressures – e.g. large colourful feathers on birds of paradise make you easier to spot by predators & mean you might have difficulty getting away)

52
Q

explain intrasexual selection

A

Intrasexual selection: competition amongst males for mating opportunities / dominance (e.g. size, ritual displays, combat)

53
Q

what do females use to measure the general health of a male

A

sexual advertisements

54
Q

What is a clue a female uses to measure the health of the male?

A

Individuals with infections or other problems may have relatively dull, disheveled plumage (unlikely to win favour amongst many females)

55
Q

What is the benefit of this females inclination after the visual signals

A

the benefit is a greater probability of having healthy offspring

56
Q

what are the 3 types of natural selection

A
  • stabilizing selection
  • directional selection
  • disruptive/diversifying selection
57
Q

explain stabilizing selection

and what is its disadvantage?

A

Select against both phenotypic extremes
Trend towards homogeneity (reduced variation)
Generally occurs in a stable environment

Disadvantage: if there is a sudden change & the stabilized phenotype becomes unfit, there is a greater risk of extinction

58
Q

give an example of stabilizing selection

A

e.g. Infant birth weight: relatively narrow range of birth weights for infants; too high or too low results in complications

59
Q

explain directional selection

A

Select for one phenotypic extreme
Shifts allele frequency curve in 1 direction (move average)
Allows for adaptation to new conditions
Often caused by exposure to a changing or novel environment
Artificial selection (breeding organisms to produce preferred phenotypes)

60
Q

give an example of directional selection

A

e.g. Bacterial resistance to antibiotics: if there is a range of resistance to an antibiotic within a population & it becomes exposed to this antibiotic, there will be directional selection towards individuals with resistance (those without will die)

61
Q

explain disruptive/diversifying selection

A

Disruptive / Diversifying Selection
Favour 2 extreme phenotypes
Select against the majority of the population (intermediate phenotypes)
May be due to new barrier (disperse population) or change in conditions (average organisms perish)
Often results in 2 sub-populations (may eventually become distinct species)
Recall allopatric speciation

e.g. Drought causing most common food source of Galapagos Finch to be lost: select for long beaks to catch wood-boring insects or thick beaks to eat cactus seeds (intermediate beak not as useful)

62
Q

give an example of disruptive selection

A

e.g. Drought causing most common food source of Galapagos Finch to be lost: select for long beaks to catch wood-boring insects or thick beaks to eat cactus seeds (intermediate beak not as useful)

63
Q

which selection favours the 2 extreme phenotypes?

A

disruptive

64
Q

which selection favours for 1 phenotypic extreme

A

directional

65
Q

which selection favours against both phenotypic extremes

A

stabilizing

66
Q

DIAGRAM OF SELECTIONS

A

SEE NOTES ON SLIDES

Biology 101 (15 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions