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Week 3- evolutionary genetics Flashcards

(81 cards)

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1
Q

what is a scientific theory

A

an explanation supported by evidence

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2
Q

what did Darwin hypothesised

A

that present-day species are descendants of ancient ancestors that have evolved

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3
Q

why do populations change over generations

A

to become more adapted to their environment

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4
Q

what species are naturally selected

A

when there is a frequently recurring struggle for existence, any being that varies slightly in a manner profitable to itself, will have a better chance of surviving

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5
Q

when was the origin of species discovered

A

1859

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6
Q

what is natural selection

A

organisms with certain inherited traits are more likely to survive and reproduce that those with other traits.
Frequency of alleles in a population can change over time

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7
Q

what theory did Alfred Wallace come up with

A

similar conclusion to Darwin- survival of the fittest

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8
Q

what was Darwin

A

A naturalist

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9
Q

what tends to happen to closely related species that occupy different ecological settings

A

they have different characteristics

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10
Q

what happens to populations that are physically isolated

A

tend to differ

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11
Q

what were Darwins theories

A
  • All species derive from very different species living in the past
  • Species change over time because bearers of different traits have different probabilities of contributing offspring to the next generation
  • Splitting of single species into two or more species has occurred (Speciation)
  • Evolution occurs by the gradual transformation of populations over long periods of time
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12
Q

what processes are required in natural selection

A
  • competition
  • variation
  • heritability
  • iteration
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13
Q

why is there competition in natural selection

A

Many more individuals are born than survive

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14
Q

why is there variation in natural selection

A

Individuals vary in traits directly related to their ability to survive and reproduce

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15
Q

what is heritability in natural selection

A

advantageous traits are passed on to offspring

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16
Q

what is iteration in natural selection

A

process is repeated generation after generation over long periods of time

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17
Q

what does the modern synthesis theory state

A

genes are responsible for the inheritance of characteristics

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18
Q

what does the modern synthesis combine

A

Darwinian selection and Mendelian inheritance

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19
Q

what is the basic explanation of modern synthesis

A

populations evolve, not individuals. speciation is usually due to the gradual accumulation of small genetic changes

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20
Q

what does the Modern Synthesis Theory suggest that genes are responsible for

A

the inheritance of characteristic

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21
Q

what does the Modern Synthesis Theory suggest that speciation is due to

A

the gradual accumulation of small genetic changes

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22
Q

what do fossils show

A

that species existed in the past that no longer exist today, and species exist today that did not exist in the past

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23
Q

what do fossils provide solid evidence towards

A

the fact that organisms from the past are different to those we see today; they show a progression of evolution

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24
Q

what are vestigial structures

A

an anatomical feature or behaviour that no longer seems to have a purpose in the current form of an organism

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25
how did blind cave fish lose their complex eye structure
adaptation to cave dwelling
26
what is the vestigial genes in blind cavefish
one of the genes responsible for eye loss in cavefish also increases the number of taste buds on the ventral surface of the head, which helps them find food more effectively
27
what would natural selection for the increase in taste buds in cavefish promote
blindness
28
what is homologous
Similarities because they derive from a common ancestral source
29
analogous
Similarities because they perform a similar function and not because they come from a common ancestor
30
what are homologous structures
similar structures in organisms with shared ancestry
31
where are homologous structures derived from
the same common ancestor but may not have the same function
32
what are analogous structures
Less-related species living in similar environments have similar body forms, though often involving different body parts.
33
how are analogous structures formed
From variations in a population, the environment selects those that best help an organisms survive in that environment.
34
what can spines be used for in different species
insulation, camouflage, signalling, sensing, and defence
35
what does embryological similarities demonstrate
a shared set of genes between groups of organisms, suggesting common ancestry.
36
26
37
what does comparative genomics demonstrate
shared genes for many traits between related species, suggesting descent from a common ancestor
38
what does the direct observation of change over time show
through artificial selection experiments, the mean phenotype can be rapidly advanced, and phenotypes can be produced that are well beyond the range of variation in a base population.
39
what is contemporary evolution/ evolution in ecological time
evolutionary change in response to changing environmental conditions
40
what is one of the outcomes of evolutionary change
the development of species
41
what are species
a group of organisms that can potentially interbreed with one another to produce viable, fertile offspring.
42
what is the outcome of different species interbreeding
often produce sterile or less viable offspring
43
what are the mechanisms of reproductive isolation
- prezygotic - potzygotic
44
what is the pre zygotic mechanism
prevent members of different species from mating to produce a zygote
45
how does the prezygotic mechanism work
- habitat isolation - temporal isolation - behavioural isolation - gametic isolation - mechanical isolation
46
what is postzygotic mechanism
keep hybrid zygotes from developing into healthy, fertile adults
47
32
48
what is speciation
the process where one species can no longer reproduce with and therefore is different from another species
49
what is allopatric speciation
geographic separation of populations from a parent species
50
what is sympatric species
remaining in one location
51
how does allopatric speciation occur
evolution into two or more descendant species after a period of physical separation caused by a geographic barrier leading to reproductive isolation
52
what are some some examples of geographical barriers that leads to allopatric speciation
- mountain range - body of water - changed landscape - crossing a pre-existing barrier
53
what is sympatric speciation
divergence without geographic seperation
54
how does sympatric speciation happen
- mutation/polymorphism within a species - polyploidy
54
how does sympatric speciation happen
- mutation/ polymorphism within a species - polyploidy
55
what is polyploidy
heritable condition of possessing more than two complete (homologous) sets of chromosomes
56
what is microevolution
changes in allele frequencies in a gene pool from generation to generation
57
what are the causes of microevolution
- genetic drift - natural selection - gene flow - mutation - non-ramdom mating
58
what does a reduction in genetic variation lead to
inability to adapt to new selection pressures, because genetic variation that selection would act on may have drifted out of the population
59
what 2 factors may cause genetic drift
- bottleneck effect - founder effect
60
what is the bottleneck effect
leads to reduced genetic variability following some large disturbances that removes a large portion of the population. The surviving population often does not represent the allele frequency in the original population
61
what is the founder effect
when a few individuals from a large population colonise an isolated habitat which may lead to reduced variability
62
what is natural selection
differential success in reproduction based on heritable traits results in selected alleles being passed to relatively more offspring
63
when does natural selection occur
when one allele (or combination of alleles of different genes) makes an organism more or less able to survive and reproduce in a given environment
64
which mechanisms cause natural selection
- directional selection - disruptive selection - stabilising selection
65
what is directional selection
where one extreme phenotype is more fit than all the other phenotypes
66
what does directional selection favour
individuals at one end of the phenotypic range and is most common during times of environmental change or when moving to new habitats
67
what is disruptive selection
where both extreme phenotypes are more fit than those in the middle
68
what does disruptive selection favour
extreme over intermediate phenotypes, and occurs when environmental change favours an extreme phenotype
69
what is stabilising selection
where the intermediate phenotypes are more fit than the extreme ones
70
what does stabilising selection favour
intermediate over extreme phenotypes and reduces variation and maintains current average
71
what is gene flow
movement of alleles between populations
72
what tends to happen to gene flow over time
reduction in variation
73
what does natural selection normally select
pre-existing traits (alleles)
74
what is a mutation
a change in an organism's DNA and is represented by changing alleles
75
what is the original source of variation
mutations
76
how do mutations affect the composition of the gene pool
mutations can be transmitted in gametes to offspring
77
what is non-random mating mating
when individuals choose mates non-randomly with respect to genotype
78
what is positive non-random mating
same genotypes
79
what is negative non-random mating
different genotypes
80
what is inbreeding
mating with close relatives

human genetics (9 decks)

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