Brainscape's Knowledge GenomeTM

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


See full index

Bio life complexity > what is Evolution > Flashcards

what is Evolution Flashcards

You may prefer our related Brainscape-certified flashcards:
Biology 101 flashcards
1
Q

Natural selection and evolution are not the same thing

A
  • Fisher began his famous book The Genetical Theory of Natural Selection (1930) with the sentence “Natural Selection is not Evolution.”
  • Natural Selection : Individuals with phenotypes most suited to the environment (fittest) are more likely to produce offspring.
  • Natural Selection is a ‘driver’ of evolution and acts on heritable variation within a population
  • Evolution is the cumulative change in a population or species over time.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

The Galapagos Islands

A

-Valuable environment for studying and understanding natural selection and evolution
-• Galapagos : a series of many islands
• Age from ~0.5 to ~3 million years old
• A wide range of habitats

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

Macroevolution : the concept

A

Major evolutionary changes among large taxonomic groups( at or above the species level) over long periods of time.

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

Microevolution : The concept

A

Microevolution studies the evolutionary ‘agents of change’ that shape the genome within a population

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

The Hardy-Weinberg Theorem

A

• Under certain conditions , allele frequencies will not change from one generation
to the next. They remain in equilibrium and dominant alleles can’t over run recessives.
p2 + 2pq + q2 = 1.0

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

The Hardy-Weinberg theorem

Allele frequencies remain in equilibrium (do not change) if five unrealistic conditions are met

A
  • No migration
  • No mutation
  • Equal fitness
  • The population size is infinite
  • Mating is random
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

chi-squared test

A

x2=Sum(O-E)/E and the compare at d.f(n-1_

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

What does a population mean from an evolutionary perspective?

A
  • A population is a group of organisms that interact and share genetic information
  • Interact Same place and time
  • Share Genetic Information Interbreed and produce viable offspring
  • A population can vary in size, distribution and structure and influence evolutionary processes
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Why is it useful to define populations?

A
  • Spread of disease
  • Track resistance (e.g. insecticide)
  • Risk of inbreeding
  • Financial – bioprospecting
  • Pest control – e.g. Fox, feral cats
  • Conservation – monarch butterflies
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

gene pool

A

The gene pool refers to all the genetic variation that exists among all the individuals of a population

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

effective population

A

The number of individuals that contribute

offspring to the next generation

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

population size, distribution and structure and influence evolutionary processes

A

– Mutation (more individuals, more chance of mutation)
– Natural Selection (smaller populations fix alleles that are under selection faster)
– Genetic Drift (smaller populations are more likely to fix alleles via random chance)
- Gene Flow can influence the flow of genetic information between populations
• Distribution - The area a population inhabits and density of the individuals
– mating Random vs. Non-random
• Mating can affect population structure and influence the effective population size (Ne)

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

Germ-line versus somatic mutation

A

Germline Mutation
• Affects gametes (eggs, sperm)
• Mutation transmitted via sexual reproduction
• Mutations in the germline create new variation (alleles) and can be heritable
Somatic Mutation
• Affects all the Daughter cells of a single cell.
• Not heritable (but can be passed down in plants for example, through vegetative reproduction)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Mutations alter DNA and can introduce variation to a population

A

-Induced DNA mutation via chemicals and radiation
-Spontaneous DNA mutation via replication errors
• Mutations can arise in all parts of the genome
• When mutations occur in a gene or their regulatory regions they may impact on an
organism phenotype

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

Mutations can impact gene expression and function

A

Mutations in regulatory regions of genes may affect expression
• Have no change in expression
• Increase/decrease abundance
• Presence or absence in tissues or cells
Mutations in coding regions of genes may affect (protein) function
• Be functionally the same
• Large or small functional difference

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

Mutations can occur at different scales within the genome have differing impacts.

A

Smaller Changes: More common but often less genetic consequence
-A single base changes (substitution)
-DNA of different sizes is inserted/deleted (Indel) into the middle of an existing sequence.
-If Indel is not a multiple of three then it can lead to a frameshift
Larger Changes: Less common but often greater genetic consequence
-DNA is copied a second time and/or flipped around
-Chromosomes are joined together or gained/lost (Aneuploidy)
-Entire genomes are duplicated

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

Mutation rate in human

A
  • Human : approximately one SNP (single nucleotide polymorphism) per 30 million base pairs (3 x 10-8)
  • This figure is per genome (N)
  • It has been estimated that we inherit (approximately) 100 new mutations from each of our parents, so ~200 new mutations all up (2N, as we are diploid)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Mating Systems

A

Random Mating: Equal probability that mating will occur between any two individuals in a population
Non-Random mating: Probability bias
Assortative mating
Disassortative mating

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

Assortative mating

A 
Mate with individuals that share alleles
‘Like with Like’
Can result in
• Inbreeding is an extreme case
• Less genotypic diversity
• Increased homozygosity
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Disassortative mating

A 
Mate with individuals that do not share alleles
‘Opposite Attract’
Can result in
• Increased genotypic diversity
• More heterozygosity
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Galapagos medium ground finch

A
  • Island : Daphne Major
  • Medium ground finch live their entire lives on the island
  • Few plant species – producing hard or soft seeds that the birds eat
  • The population shows variation in beak size
  • Large beaks open larger, hard seeds faster and smaller beaks are better at smaller seed
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Natural Selection : avian attack on clay models

A

• Measuring natural selection on coat colour in oldfield mice.
• Clay models of mice were painted to resemble habitat colour and placed in either mainland or beach habitats.
• Predation was highest when coat colour provided no
camouflage.

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

Requiermernt for Natural Selection

A
  1. Variation
    Individuals within a population must have variation for selection to act. Variation can occur in appearance, behaviour or physiology.
  2. Heredity
    Offspring need to resemble their parents more than unrelated individuals. Traits must be heritable.
  3. Selection
    Some forms are more successful at reproducing in a particular environment.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Selection can act in different ways on a population

A 
Directional selection (positive selection) favours individuals on one end of the distribution of phenotypes (small fish have higher fitness than large fish)
Stabilizing selection favours individuals in the middle of the distribution of phenotypes present in a population (for example, by acting against individuals at either extreme).
Disruptive selection (right) favors individuals at either end of the distribution (shaded area).
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

Selection acts on dominant alleles faster than recessive alleles

A
  • Favoured dominant alleles (red line) immediately increase in frequency.
  • Selection is not likely to drive a dominant allele to fixation, as recessive alleles can “hide” in the heterozygous state.
  • Favoured recessive alleles (blue line) are not exposed to selection initially because they are likely to occur only in heterozygous genotypes.
  • Once recessive homozygotes begin to appear, they quickly fix in the population
26
Q

Artificial selection

A

… is similar to natural selection, except that it results from human activity. When breeders nonrandomly choose individuals
with economically favourable traits to use as breeding stock, they impose strong artificial selection on those traits.

27
Q

Balancing selection, the heterozygote advantage

A

Heterozygote advantage occurs when selection favours heterozygous individuals over homozygotes

28
Q

Fitness and relative fitness

A 
Fitness refers to the success of an organism at surviving and reproducing and thus contributing offspring to future generations.
Relative fitness (w) describes the success of a genotype at producing new individuals.
Relative fitness standardized by the success of other genotypes in the population and
ranges from 0 to 1.0
29
Q

calculate relative fitness

A

O/E than divide the number with highest value

selective advantage value: divide the two value against each other

30
Q

Genetic drift

A

-Genetic Drift involves random changes in allele frequencies that are directionless
-When alleles become more or less common simply by chance
-There is always an element of randomness in determining which alleles
are passed on by the parental population
-Allele frequency changes via genetic drift results from ‘sampling error’
• Cannot predict which allele will be fixed/lost

31
Q

Which population is most susceptible to genetic drift

A

-The effects of genetic drift occur in all populations but is most pronounced in small populations
-In a small populations genetic drift is a stronger evolutionary agent of change
• Outcomes are more unpredictable
• Probability of large changes is greater
-Large populations buffer genetic driftmaking it a less significant agent of change
• Populations don’t need to be infinite size, but large enough that random sampling effects do not impact allele frequencies significantly

32
Q

• Genetic bottleneck

A

: caused by events that reduces the size and genetic diversity of a population significantly`
Events that randomly impact individuals in a population - not related to Natural Selection
• Impact allele frequencies in a population by chance
• Populations therefore contain a smaller, mostly random sample of the alleles that were present in
the original population
-The chance that loosing alleles after bottleneck or founder events depend on their initial frequency plus the new population size

33
Q

Founder effect

A

-caused by a small number of individuals founding a new population. Random differences in allele frequencies occur when a small colony splits from a large population

34
Q

what happen after bottleneck or founder effect

A
  • Following a bottleneck or founder event, population size may recover quickly, but genetic diversity will not
  • New populations arising from a very small number of individuals can cause this population to differ considerably from the parent population
35
Q

Gene flow

A

Gene flow is the transfer of genetic information from one population to another
• Gene flow occurs via migration, movement or hybridisation.
• The impact of gene flow on the gene pool depends upon
i. The level of migration, movement or hybridisation (how often)
ii. The differences in allele frequencies between populations
Gene flow also occurs when individuals share generic information via hybridisation

36
Q

gene flow effect on population

A
  • Gene flow tends to homogenize more connected populations

- A lack of gene flow promotes interpopulation differentiation

37
Q

calculate the impact of gene flow

A 
∆p = the change in f(A) in the resident population
after one generation of migration
Dp = m(x-p)
In residents f(A) = p f(a) = q
In migrants f(A) = x f(a) = y
38
Q

Speciation

A

the evolutionary process by which new species arise through reproductive isolation.
Speciation causes one evolutionary lineage to split into two or more lineages.

39
Q

Reproductive barriers

A

prevent gene flow and enable speciation

  1. Pre-mating Isolation
    - geographical isolation
    - behavioural isolation
  2. Pre-zygotic Isolation
    - mating time differences
    - ecological differences
  3. Post-zygotic Isolation -fertilized egg/offspring inviable
40
Q

Pre-mating reproductive isolation (geographic)

Allopatric speciation

A

-Geographical isolation prevents reproduction and can enable the agents of change to drive speciation (allopatric speciation)
Agents of change cause genetic divergence between populations
• Mutation ->• Chromosomal/DNA differences
• Selection ->• Change phenotype/behaviour
• Genetic drift->• Reproductive isolation
-Selection for different mating signals creates reproductive isolation in the same (sympatric) population.

41
Q

Pre-mating reproductive isolation (behaviour)

A

Genetic, behavioural, physiological, or ecological aspect preventing the
sperm from one species from fertilizing eggs of another species

42
Q

Post-zygotic Isolation

A

Isolating barriers that act after a zygote begins to develop

  • fertilized egg fails to develop
  • hybrid offspring sterile
43
Q

Sympatric speciation

A

speciation in the same location

44
Q

How is a species defined?

A

Biological species concept : species are groups of actually (or potentially) interbreeding natural populations that are reproductively isolated from other such groups.
Phylogenetic species concept : species are the smallest possible groups whose members are descended from a common ancestor and who all possess defining or derived characteristics that distinguish them from other such groups
Ecological species concept
A concept positing that species are sets of organisms that are adapted
to a particular set of resources, that is, to the same ecological niche.

45
Q

Cichlid fish are an important evolutionary study system

A
  1. Unparalleled degree of phenotypic and taxonomic diversity has arisen in sympatry – new species without geographical barriers
  2. Speciation has occurred through macrohabitat adaptation and specialization. Mate preference traits (often colour) can cause disruptive selection
  3. Adaptive radiation : very rapid evolution of many species through adapting to underutilized ecological niches
46
Q

Why is it useful to define a species

A 
Conservation
– categorizing endangered species
Food
– classifying fruits and vegetables
Safety
– e.g. Bacillus anthracis (anthrax) and Bacillus thuringiensis (pesticide)
Medical
– diagnose and treat infections (bacteria and viruses)
Recreational
– implementing catch limits when fishing
47
Q

Potential outcomes of hybridization

A

Adaptive introgression : inheritance of beneficial variation from related species
that accelerate adaptation to, and survival in new environments

48
Q

Hybridization between Hominids

A
  • DNA and fossil evidence show humans, Neanderthals, and Denisovans represent separate, parallel lineages descended from a common ancestor (★).
  • Molecular studies indicate that modern humans interbred with Neanderthals and Denisovans
49
Q

alternate explanation to hybridization

A

alleles pre-date speciation

50
Q

what does Genes code incolve

A

Genes code for proteins that are involved in complex biological, cellular and molecular functions that together contribute to phenotype
• Evolution has been discussed from the perspective of one set of alleles and distinct phenotypic differences
• In reality, many genes and their alleles are involved in determining a phenotype
• Quantitative Traits

51
Q

QUALITATIVE TRAIT

A

Multiple genes contribute to a phenotype in a cumulative way
• While all genes are required, some may be more important or influential than others
• The alleles influence or improve a phenotype may be the subject of selection
-Biological, cellular and molecular functions are part of a larger network of complex interactions and feedbacks

52
Q

Molecular genetics and genomics

A

Molecular genetics and genomics involves the sequencing and analysis of select genes or entire genomes
Molecular Genetics involves the study DNA sequences encoding specific genes to understand function.
Genomics is the study of the DNA sequences of all the organism’s genes – called the genome

53
Q

Investigate variation using a range of approaches

A
  • Compare Specific Situations
  • Look across the distribution of a phenotype
  • Look at evolutionary relationships
54
Q

Whole genome sequencing

A

Whole genome sequencing (reference genome)
i) Extraction of DNA
ii) Create DNA “Library”
iii) Sequence
iv) Assemble data (and annotation)
• Collect samples
• Create “Libraries” and sequence
• Investigate one locus/gene or entire genome
• Identify SNPs and other genetic variation

55
Q

Technological advances in genomic

A

Genomes of some organism are very big
• Need a sufficient sample size to determine relationships which may involve significant sequencing
• Complex analysis with big data requires bioinformatics.

56
Q

COVID-19 Spread

A
  • Small genome; nucleic acid is RNA
  • Replicate via asexual reproduction
  • Replication is not accurate as in other life forms so mutations arise more rapidly
  • Mutations and mode of inheritance means we can fingerprint each case
  • The person they caught it from will appear almost identical
  • Transmission to additional people will likely have more differences
57
Q

Phylogenetic relationships - Cladogram

A
  • Analysis of relationships between the nucleic acid sequences to create a tree of relatedness
  • Compare transmission and epidemiological information with the established evolutionary relationships
58
Q

how mitochondria help Indigenous Australian people’s migration into the continent

A 
Mitochondrial Genome (Mitogenomes)
• Inherited maternally and represents clonal lineages
• Circular double stranded DNA molecule
• Mutations occur
• Haploid genome - Haplotypes
59
Q

Indigenous Australian people’s migration into the continent Study Methodology

A 
Mitogenome
From hair samples collected from
early European settlement 
Locational Information
Obtained at time of hair sample
collection
Temporal
Molecular clock (mutation rates)
calibrated with archaeological data
60
Q

Result ofPhylogenetic analysis

A

Four major haplotype groups identified which have deep splits between them
Haplotype groups diverged in first 10,000 years and remained distinct for the next 40,000 years
Single Rapid Migration along the East or West coasts in first 10,000 years
• Regional patterning developed post continent wide settlement where little movement occurred across the landscape for next 40,000 years
Continuous presence of populations in discrete geographic regions for long period Consistent with Indigenous peoples long cultural connection with land

Bio life complexity (6 decks)

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