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Genetics > Evolution > Flashcards

Evolution Flashcards

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Biology 101 flashcards
1
Q

What is natural selection?

A

best adapted organisms survive and pass on their traits to their offspring

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2
Q

What are Darwins assumptions

A
  1. individuals within species are variable
  2. some variations are passed onto offspring
  3. in most generations, more offspring are produced that can survive
  4. survival and reproduction are not random - survival of fittest
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3
Q

What is evolution?

A

survival of the fittest
occurs because of changes in allele frequencies
fittest genotypes vary between populations
divergence of populations leads to speciation

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4
Q

what is the modern synthesis of evolution?

A

considered in terms of changes in allele and gene frequencies over time, and the average action of selection on genotypes

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5
Q

when does selection act on alleles?

A

in relation to their average contribution to their action on the individuals that carry them

acts on levels of individuals
transmission of alleles important

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6
Q

When does selection operate?

A

to remove less fit variants, or increase variants with greater fitness

artificial selection
- humans affected genotypes of dogs & can remove and select for different phenotypes

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7
Q

what is invasion of rare mutants?

A

new alleles are constantly created
dominant allele are always expressed, selection against will remove excess alleles

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8
Q

What is genetic drift?

A

chance difference in transmission of alleles, leading to fluctuations in allele frequency
greater influence than selection
increases rare recessive alleles

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9
Q

What is a genetic bottleneck?

A

random allele is lost
founder effect
significant as reduction of population
completely random and small surviving population

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10
Q

what is balancing selection?

A

how variation is maintained in a population
selection both for and against

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11
Q

what is frequency dependent selection?

A

Rare alleles producing unusual phenotypes may be predated on less than those with the main allele
Alleles can become common and predators learn their patterns

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12
Q

what is fluctuating selection?

A

also select for rare alleles
unstable and changeable
may favour opposing phenotypes over short timescales

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13
Q

what is fitness?

A

Used to measure reproductive success, described as the ability to both survive and reproduce and is equal to average contribution of the gene pool of the next generation that is made by an average individual of the specified genotype of phenotype.

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14
Q

what ate the methods for measuring fitness?

A
  1. relative survival of genotypes within a generation
  2. changes in gene frequencies between generations
    deviations from hardy-weinburg ratios
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15
Q

what is fitness equation?

A

W = 1 -s
w is fitness
s is selection

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16
Q

selection determines how fast allele frequencies change

A

when s is high, allele frequencies change rapidly

17
Q

selection example

A

peppered moths
mark release recapture experiments and found dark forms adapted to survive in industrial revolution

18
Q

mark release recapture technique

A

tested how well survived in different environments
recapture allows to see survival rate
assume optimal survivorship
ca then calculate selection coeffecient

19
Q

what is an adaptive landscape?

A

natural selection tends to move populations towards peaks of hills

never ending evolutionary journey
visualise relationship between genotypes and phenotypes

20
Q

what is stabilising selection?

A

stabilises a population
intermediate variants are selected for
most common

21
Q

what is directional selection?

A

individuals at one extreme are selected for
shift

22
Q

what is disruptive selection?

A

individuals at both extremes are selected for
bimodal distribution

23
Q

what is sexual selection?

A

competition for mates
maximises reproductive success
even at potential cost to survival
extreme case of natural selection

24
Q

what does kin selection refer to?

A

changes in gene frequency across generation driven by interactions between related individuals

Natural selection of genes that tend to cause the individuals bearing them to be altruistic to close relatives
helping your relatives, even at a cost to yourself, you may be promoting the success and transmission of genes that you share in common

25
Q

what is the coefficient of relatedness?

A

parent transmits 50% of genetic information to offspring
100% relatedness to self
50% to each parent
every time take step back in relation, halves

26
Q

what is Hamiltons rule?

A

fitness as the number of an individuals allele in the next generation
notion of inclusive fitness

27
Q

what leads to relatedness?

A

cost of not producing / benefit of helping kin reproduce
<

28
Q

Hamiltons rule equation

A

rB<C

r= probability gene picked randomly is identical by descent
B= additional reproductive benefit
C= reproductive cost to individual

promotes passing of genes from one generation to the next

29
Q

what is phylogenetic?

A

estimating relatedness between species based on sequence data
relatedness between species

30
Q

how do you read phylogenic tree?

A

distance between nodes important for relationships
nodes are flexible and individual taxon can move around the tree

31
Q

what can phylogenetic be used to do?

A

use molecular genetics to infer relatedness
homologous genes to create a tree

32
Q

what are paralogous genes?

A

arise through duplications in the genome
different genes created

33
Q

what are orthologous genes?

A

genes that have split when new species have been formed
want orthologous as have the same function

34
Q

What is a species?

A

a group of organisms capable of interbreeding to produce fertile offspring
occur at node in phlyogenetic trees

35
Q

what’s allopatric speciation?

A

different places leading to speciation
separate by location

36
Q

what’s sympatric speciation?

A

same geographical location but have managed to diverge

37
Q

what is speciation reinforced by?

A

pre-mating isolation:
behavioural choices, spatial constraints

post-zygotic isolation:
availability, hybrid sterility

Genetics (21 decks)

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