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GBB > 1. Trait Variation > Flashcards

1. Trait Variation Flashcards

1
Q

Evolution via natural selection

A

-cognitive mechanisms assumed to have developed via natural selection

  • evolutionary theory (Darwin, 1844) principles:
    1. Principle of variation
    2. Principle of inheritance
    3. Principle of adaptation
    4. Principle of evolution
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2
Q

. Principle of variation

A

Individuals within a species show variation in their physical and behavioural traits

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3
Q

Principle of inheritance

A

Some of this variation is heritable

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4
Q

Principle of adaptation

A

Individuals are in competition with one another for scarce resources and some inherited variation will have survival advantages

-adapt to environment to survive

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5
Q

Principle of evolution

A

As a consequence of being better adapted to an environment, some individuals will produce more offspring, who will inherit the same advantages
-this is called fitness (if it affects reproduction)

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6
Q

Sexual selection

A
  • creation and maintenance of features essential for attracting the opposite sex and defending ones status
  • hierarchy
  • aids in transferring genes - reproduction

-natural selection and sexual selection work together

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7
Q

Inclusive fitness

A
  • William Hamilton (1964)
  • reformulated evolutionary theory by showing that measure of an individuals productive success (fitness) was too narrow

-inclusive fitness: characteristics will be selected that improves the chances of individuals genes being passed directly or via relatives

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8
Q

Animal behaviour: evolution and mechanisms

A

-the evolutionary process by which some genes in a population spread more than others do, causing species to change over time:

  • natural selection
  • mutations
  • adaptive behaviour
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9
Q

Natural selection

A

-the principle that, among the range of inherited trait variations, those that lead to increased reproduction and survival will most likely be passed on to succeeding generations

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10
Q

Mutations

A
  • random errors in gene replication (method of adaptability) that lead to a change in the sequence of nucleotides in the genome
  • results in changes in specific gene expression, brain function and behaviour
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11
Q

Adaptive behaviour

A
  • an evolutionary adaption that enhances survival and reproductive success
  • evolves as natural selection fine-tunes an animal to its environment
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12
Q

Adaptive problems

A
  • eg. Finding a mate, finding food, avoiding predation, disease
  • can affect reproductive success (fitness)
  • each problem tackled by adaptive changes in physiology and behaviour (mode of inheritance)
  • social scientists accept that our bodies have been sculpted by evolutionary forces
  • evolutionary psychologists argue that our psychological mechanism/behaviours have been shaped by evolution
  • how our behaviours function as adaptations (physiology regulated behaviour)
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13
Q

Proximate causation

A

-the immediate psychological, physiological, biochemical and environmental reasons that a certain trait exists

  • sensory systems - to be able to perceive danger
  • muscle contraction - to be bale to run from danger
  • cellular activities regulate development - nerve function
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14
Q

Ultimate causation

A
  • the reason a certain trait increased fitness in the evolutionary past
  • how does the internal machinery work
  • why does it work that way
  • is that behaviour an adaptation
  • how does that behaviour allow the individual to survive, find food, find mates etc.
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15
Q

Not all behaviours are adaptive

A
  • an adaptation represents a trade-off between different survival and reproductive needs (eg. Having a large body)
  • environment may alter more rapidly than the organism can evolve
  • adaptation is not alway adaptive in every circumstance
  • not all features are adaptive (navel)
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16
Q

Stephen Jay Gould (1991)

A
  • cautioned the use of just-so stories
  • features that may once have been adaptive for one function may have changes over time to serve a different function (exaptations/co-option)
  • other features may look like adaptations but are design constraints (spandrels)
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17
Q

Exaptations/Co-option

A
  • a shift in the function of a trait during evolution

- eg. Feathers for warmth and then flight

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18
Q

Spandrels

A

-phenotypic characteristic that is a byproduct of the evolution of another trait, rather than a direct product of adaptive selection

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19
Q

Environmental role

A
  • Buss et al 1998
  • interactions with the environmental features during development are critical for normal development (relationship between genes and environment change over time)
  • input during development may be required in order to activate certain adaptive features (eg. Experience of sexual relationship and jealousy)
  • developmental events may channel individuals into one of several different paths (eg. Parenting style)
  • environmental events may disrupt the emergence of an adaptation (nutrition)
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20
Q

Evolutionary psychology

A
  • the study of the physiological evolutionary and developmental mechanisms of behaviour and experience
  • strong emphasis on brain functioning
  • biological explanations:
    1. Physiological
    2. Ontogenetic
    3. Evolutionary
    4. Functional
  • deep understanding of a behaviour is tied to explain it from each perspective
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21
Q

Physiological explanation

A

-related a behaviour to the activity of the brain and other organs

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22
Q

Ontogenetic explanation

A

-described the development of a structure or behaviour

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23
Q

Evolutionary explanation

A

-reconstructs evolutionary history of a behaviour

24
Q

Functional explanation

A

Why a structure or behaviour evolved

25
Q

Brain size of humans

A
  • grown 3x in size
  • biggest increase = prefrontal cortex (executive functioning)
  • humans can plan behaviours, make decisions, think creatively, control bodily processes
26
Q

Bidirectional view

A
  • environmental and biological conditions influence each other
  • evolution gives us bodily structures and biological potentialities but does not dictate behaviour
  • individuals create behaviour in the context of culture
27
Q

Brain size of primates and juvenile period

A

-extended childhood allows time to develop a large brain and learn complexity of human society

28
Q

Mendel (1800s)

A
  • crossed a line bred true for brown seeds with one bred true for white
  • first gen all had brown seeds
  • second gen 3/4 brown 1/4 white
  • white (ww)
  • brown (BB)
29
Q

Phenotype

A

-observable traits

30
Q

Genotype

A

Traits present in the genes

31
Q

Allele

A

-two genes that control the same trait

32
Q

Homozygous

A

-2 identical alleles

33
Q

Heterozygous

A

2 different alleles

34
Q

Chromosomes

A

Thread like structures made of DNA

35
Q

DNA

A

Complex double-helix molecule that contains genetic information

  • 2m of DNA must fit into 5-10 micrometer cell nucleus
  • the same in all somatic cells of an organism
36
Q

Genes

A
  • units of hereditary information in each chromosome
  • humans have 25,000 genes
  • genes direct cells to reproduce themselves and to assemble proteins
  • genes collaborate with eachother and with non genetic factors inside and outside body
  • genetic expression is affected by the environment
37
Q

Proteins

A

-building blocks of cells and regulators that direct the body’s processes

38
Q

Meiosis vs mitosis

A
  • mitosis: produces 2 daughter somatic cells
    • no recombination
    • somatic cells are clones of the original
  • meiosis: produces 4 daughter cells (germ cells)
    • recombination of chromosomes in prophase 1
    • germ cells are not clones of the original cell because each gamete has exactly half as many chromosomes as original cell
39
Q

Karyotype

A

-number and appearance of chromosomes in the nucleus of a eukaryotic cell

40
Q

Sources of variability

A
  1. Combining genes of bother parents increases genetic variability
  2. Identical twins develop from a single zygote that splits in 2
  3. Fraternal twins develop from separate eggs and sperm
41
Q

Gene linked abnormalities

A

-single gene disorder

  • autosomal dominant
  • autosomal recessive
  • x-linked
  • y-linked
  • mitochondrial
42
Q

Chromosomal abnormalities

A
  • occur when there is an error in cell division following meiosis or mitosis
  • caused by a missing, extra, or irregular portion of chromosomal DNA
43
Q

How are traits studied

A
  • human behaviour and personality characteristics are observable and measurable components of a persons phenotype - which is the detectable expression of a persons genotype interacting with his or her environment
  • behaviour genetics seeks to discover the influence of heredity and environment on individual differences in human traits and development
  • linkage studies look for patterns of inheritance of genetic markers in large families
44
Q

Genetic marker

A

A segment of DNA that varies among individuals

45
Q

Heritability

A

-the statistical es time of the proportion of the total variance in some trait that is attributed to genetic differences among individuals within a group

46
Q

Limitations of heritability

A
  1. An estimate of heritability applies only to a particular group living in a particular environment
  2. Heritability estimes to not apply to individuals, only to variations within a group
  3. Even highly heritable traits can be modified by the environment
47
Q

Determining heritability

A
  1. Examining whether children more closely resemble their adoptive or biological parents
  2. Comparing monozygotic and dizygotic twins
  3. Examining identical twins raised in different households
48
Q

Shared environmental experiences

A
  • parents personalities
  • intellectual orientation
  • Family socioeconomic status
  • neighbourhood
  • shared environment accounts for little variation in children’s personality or interests
49
Q

Non-shared environmental experiences

A

unique experiences:

  • within family
  • outside family
  • not shared by another sibling
  • heredity influences the non-sharing environments through hereditry-environment correlations
50
Q

Heredity-environment correlations

A
  • individuals influence environment, yet individuals inherit environments
  • genotype-environment correlations change as children grow
  1. Passive GE-interaction: parents provide rearing environment
  2. Evocative GE-interaction: when genotype elicits certain types of physical and social environments
  3. Active GE-interactive: when children seek out compatible and stimulating environments
51
Q

IQ

A
  • genetic influence grows stronger with age
  • 0.5 for children/adolescents
  • 0.6-0.8 for adults
  • scores of adopted children are highly correlated with their biological parents
52
Q

MZ and DZ concordance rates of psychiatric disorders

A
  • complex diseases the aggregate in families but dont segregate in simple Mendelian manner
  • molecular genetic studies explain only 1-2% of heritability (but only 2% of genes encode proteins)
  • population estimate of 30-80% inheritability
  • epidemiological studies have demonstrated correlations between life experiences and psychiatric disease risk, but are unable to detect any specific causal environmental hazards
53
Q

Prevalence and incidence

A
  • both are measures of distribution of a disease in a population
  • prevalence: measure of the # of cases in a certain population for a specific period of time
  • incidence: measure of the # of NEW cases of the disease
  • prevalence used to refer to how widespread a diseases has become
  • incidence used to refer to the rate at which the disease is manifested in a certain population
  • incidence more reliable to determine risk of certain disease in a population
54
Q

Multifactorial disorders

A
  • diseases affected by multiple genes (polygenic) in combination with lifestyle/environmental factors
  • some genes could affect other genes through transcription factors
  • no clear cut patterns of inheritance
  • difficult to treat
55
Q

Missing heritability of complex disorders

A
  • discrepancy between epidemiological variation explained by DNA sequence differences is referred to as the missing heritability
  • art of heritability being hidden in numerous weakly contributing genetic risk factor patterns or linkage disequilibrium
  • heritability estimates being inflated by epistemically gene interactions (genes masking each other’s presence or combine to produce entirely new trait
56
Q

Missing heritability and major psychosis

A

Mechanisms involved:

  • passage of epigenetic marks through germ line
  • passage of maternal RNA molecules into embryo
  • potential passage of prion proteins from parent to offspring
  • biochemical state of gametes at time of conception
  • transmission of nutrients, bacteria, antibodies from maternal circulation to offspring
57
Q

Environment and genes,brain,plasticity

A

-even highly heritable traits are not rigidly fixed and can be modified

  • poor prenatal care, malnutrition, exposure to toxins, stressful circumstances can hinder cognitive impairment (IQ)
  • good health, nutrition, mental enrichment can enhance cognitive impairment

GBB (9 decks)

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