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Evolution and Human Behaviour (PSYC2537) > 2. Natural Selection > Flashcards

2. Natural Selection Flashcards

(75 cards)

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1
Q

What is the mechanism for evolution?

A

Natural selection

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2
Q

What do terms like ‘Darwinian’ mean?

A

Evolution via natural selection

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3
Q

What does lack of understanding of evolution lead to?

A

Misunderstandings or simplification of Darwinian theory

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4
Q

What is variation?

A

The differences within a population for certain characteristics

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5
Q

Types of characteristics

A

Continuous e.g. height, IQ, attractiveness in humans

Discrete e.g. eye colour, blood type

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6
Q

Variation occurs at 2 levels

A

Phenotype & genotype

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7
Q

What is a phenotype?

A

Observable characteristics of an individual

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8
Q

How are phenotypic traits created?

A

By cells (bones, muscle, brain, etc.)

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9
Q

What are cells made from?

A

Proteins that are strings of amino acids

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10
Q

What do genes do in terms of amino acids?

A

Genes encode the sequence of amino acids

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11
Q

In natural selection, what is actually selected?

A

The phenotype

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12
Q

Two types of genes

A

Recessive & dominant

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13
Q

Alternative forms of genes are called…

A

alleles

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14
Q

Organisms with two copies of the same allele are called…

A

haploid

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15
Q

Organisms with different alleles are called

A

diploid

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16
Q

How are genes assembled?

A

Genes are assembled into chromosomes in nucleus

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17
Q

How many chromosomes do humans have?

A

46 in 23 pairs

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18
Q

How is sex determined?

A

By chromosomes - females have XX and males have XY

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19
Q

What are genes made of?

A

deoxyribonucleic acid (DNA)

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20
Q

How are genes arranged?

A

Long chain molecule, two strands bound in double helix

Two strands bound by sequences of base pairs

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21
Q

What are the base pairs?

A

Adenine (A) pairs with Thymine (T)

Cytosine (C) pairs with Guanine (G)

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22
Q

How many base pairs make up a gene (or allele)

A

Approximately 27,000

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23
Q

How do amino acids make phenotypic traits?

A

Amino acids make proteins, and from there make phenotypic traits

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24
Q

Who was the first human to know his entire genetic code?

A

J. Craig Venter

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25
How many base pairs, chromosomes and genes make up a human?
3.2 billion bade pairs over 23 chromosomes, making approximately 25,000 genes
26
What % of DNA is genes?
40%
27
What is 60% of DNA?
Non-coding, such as transposable elements, sequence repeats and junk
28
What % of our genes do we share with chimpanzees?
98%
29
What % of our genes do we share with bananas?
50%
30
How many base pairs difference between humans and chimpanzees?
Approximately 32 million
31
What characteristics must the 2% difference in DNA between chimpanzees and humans explain?
Bipedalism Bigger brains Hairlessness Language(?)
32
What are sex cells called?
Gametes
33
Sexual reproduction
Sex cells (gametes) contain 1 of each chromosome Split through meiosis, creates sperm and eggs These then combine, make embryo Chromosomes pair up, new genotype formed
34
Why is sexual reproduction relevant?
It is a major source of variation between individuals of a species
35
Different types of mutations
Single-base substitutions Single sequence repeat expansions Insertions
36
How many new mutations do we carry in our DNA?
100-200
37
What are mutations caused by?
``` Mutagens: X-rays Cosmic rays Radioactive substances Various chemicals and even 'mutator' genes ```
38
Are mutations good or bad?
Most are either neutral or damaging, but sometimes advantageous
39
Why is heredity a necessary component for natural selection to occur?
Only traits that are inherited will be exposed to evolution by natural selection i.e. hair colour, but not hair length
40
How 'heritable' are traits?
Different traits vary in heritability
41
What genes are inherited will be partly based on...
sexual reproduction
42
What is the study of heritability called?
Behavioural genetics
43
How can we estimate heritability?
Twin studies
44
Two types of twins
Monozygotic (MZ) - share 100% of genes | Dizygotic (DZ) - share 50% of twins
45
What is included in twins' assumed shared environment?
Diet Home life Parental relationships Schooling
46
What do concordance rates between twins show?
How much of trait is explained by genes and how much is explained by the environment
47
If concordance rates are larger between MZ twins than DZ twins, what does this say about the size of the genetic component?
Genetic component will be large
48
What does little difference between concordance rates in twins suggest?
That environmental influences are more important in determining phenotypic variation
49
Geschwind et al. (2003)
Measured total volume of cerebral hemispheres in both MZ and DZ twins MZ correlation was 0.87 DZ correlation was 0.56 Therefore the size of the genetic component (heritability) of size of brain structures is 0.62
50
How can we use twin studies to calculate the effect of non-shared environment?
1 - concordance rate in MZ
51
How can we use twin studies to calculate the effect of shared environment?
Concordance rate in MZ - heritability
52
Problems with twin studies
- Assumes shared environment is the same for twins - The nature of adoptive families - Adopted children have 9 months shared environment with their biological mother - prenatal effects (e.g. hormones/diet/drugs) may be large
53
Greater the heritability, more likely that trait is...
adaptive
54
TRUE OR FALSE: Traits with heritability >0 can be shaped by natural selection.
True
55
TRUE OR FALSE: Heritability has to be 100% to say that a trait is genetic.
False
56
What is the heritability of general intelligence?
Approximately 0.35
57
What are pre-requisites for natural selection?
Variation and heredity
58
TRUE OR FALSE: Evolution will only occur when there is some form of selection (i.e. natural, artificial).
True
59
Selection relies on some form of...
competition
60
Thomas Malthus
Published "An Essay on the Principle of Population" 1798 European population was growing exponentially Limited resources - competition to survive
61
What determines which traits are selected for?
Levels of competition and force of selection
62
What are K-selected species?
few offspring high likelihood to survive long generations
63
What are r-selected species?
more offspring lower survival rates short generations e.g. fish
64
How do selection pressures affect K-selected species and r-selected species differently?
r-selected species may be more rapidly and strongly affected BUT r-selected species can evolve quicker to cope with extreme selection pressures and can cope with rapidly changing environments
65
Size of selection pressure in the environment will affect levels of...
competition and selection
66
Examples of large selection pressures
Major catastrophe e.g. meteor striking the earth or lethal pandemic
67
'Endler's guppies' experiment: background
Guppies vary from stream to stream Brightness of males attracts females BUT also predators Where predator levels high --> drabber males selected for (camouflaged with gravelly floor)
68
'Endler's guppies' experiment: method
Guppies randomly assigned to ponds with either strong/weak/no predator Before predator introduced, guppies became more colourful and spotty to attract females After predator introduced, those in the 'strong' condition had less spots
69
'Endler's guppies' experiment: conclusion
Selection for predator avoidance was greater than selection by females for colourful males (due to size of selection pressure)
70
What does 'fitness' mean?
number of copies of particular allele in subsequent generations
71
What are the types of natural selection?
Purifying selection Stabilising selection Directional selection
72
3 aspects of adaptation
RELIABILITY: Does trait develop in all members of species in normal environments? EFFICIENCY: A good solution to a problem? ECONOMY: Does it do so without great costs to the organism?
73
Example of an adaptation
Imprinting
74
The adaptationist stance
If a particular trait is common in a population, then it is the result of natural selection
75
Which stance does evolutionary psychology take?
The adaptationist stance

Evolution and Human Behaviour (PSYC2537) (14 decks)

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