Test 1 Flashcards
(97 cards)
1
Q
Evolution in two phrases
A
-living things change gradually over time
-adaptations arise through natural selection
2
Q
Important conclusions about evolution verified by scientific study (5)
A
-Organisms on earth have changed over time
-The changes are gradual
-The agents split by speciation resulting in the new generation of biodiversity
-Call species have common ancestors
-adaptations results from natural selection
3
Q
Macro evolution versus microevolution
A
Evolutionary history versus evolutionary mechanisms
4
Q
What is the purpose of evolutionarily history and what does it use to prove
A
-Determining the evolutionary relationships in terms of common ancestry
-Study of long-term patterns of evolution
-Comparative data from subdisciplines of systematics biogeography palaeontology morphology development and molecular biology
5
Q
Evolution airy mechanisms operate on what level
A
The population level
6
Q
What are the four approaches used to study evolutionary biology
A
Observational, theoretical, comparative, experimental
7
Q
What are the five reasons to study evolution
A
-Children’s questions
-medicine
-agriculture
-environment
-life on earth a.k.a. biology
8
Q
What are some public doubts about evolution
A
-Extremely recent scientific concept only about 150 years
-very personal implications especially in terms of who we are and where we come from
-violates literal interpretations of religious texts
9
Q
What two main questions did Darwin face
A
-Where do species come from
-how can we explain complex adaptations
10
Q
Explain Paley’s argument from Design
A
Complex organism that suit an environment must have been designed by someone
-a theologian and naturalist
11
Q
Jean-Baptiste de Lamarck
A
-evolution
-provide a hypothesis for the causal mechanism: the inheritance of acquired characters
12
Q
Who and what was the first comprehensive theory of evolution
A
Wallace and Darwin
-natural selection
13
Q
What are the two basic ideas of the origin of species
A
-all organisms have descended with Monica fixation from common ancestors
-the process leading to adaptations is natural selection operating on variation among individuals
14
Q
Uniformitarianism and who
A
Lyell
-uniform processes
-the forces we see today are the same as previous eons
15
Q
What are the implication of uniformitarianism for Darwin
A
-the notion of a dynamic rather than a static world
-biological changes build up gradually, by the same mechanisms today as in the past
16
Q
What does Darwin notice from Malthus
A
Essay on the principle of population
-begins positive and negative selection
17
Q
Darwin’s 3 mechanisms of natural selection
A
Variation
Heredity
Fitness
18
Q
Why was Lamarck wrong
A
-inheritance only in germ cells
-genetic information cannot go from stoma to gametes
-modern interpretation in molecular terms: genetic info flows only from DNA to protein not the other way around
19
Q
Important elements of Darwins theory
(4) laws of evo
A
- Evolution occurs primarily at the level of populations
- Variation is not directed by environment
- Most fit type depends on the environment
- Survival of the fitter, evolution works with available variation will not achieve perfection
20
Q
Example of transition fossil
A
-Taktaalik roseae
-375 mya
-Nunavut
-fishapod: looks like a modern fish and a tetrapod
21
Q
Intermediate forms
A
-Archaeopteryx
-therapod and a dinosaur
22
Q
Geological lessons
A
-the earth is very old
-intermediate forms
-fossils in younger strata increasingly resemble modern species in same region
23
Q
Loss of flight
A
Watc lectur
24
Q
Vestigial character example
A
Lectureeeeee
25
Human vestigial features
-ear muscles
-appendix
-tailbone
-goosebumps
26
Evidence for vestigial characteristics in genomes
-more olfactory genes have become inactivated in species that rely less on sense of smell
27
Homology and evidence
-features that look completely different but are for the same purpose
-modifications of pre-existing structure
-500 genes shared across all life forms
-strong, shared constraint for genes involved in basic cellular function
28
Galápagos Islands
-15 main islands of volcanic origin
—oldest seamounts from 5-10 million
—youngest islands 700kya to 1 Mya
-flora and fauna colonized from mainland South America
—species capable of long-distance dispersal
—distinct forms and species on different islands provide evidence of early stages of speciation
-5 weeks on the islands but his observations formed the foundation for his theory of evolution
29
San Cristobal island
-uninviting
-cacti example
—seeds dated by birds and brought over
-Tortoises on different islands have different shell shapes
30
Adaptive radiation
-the evolution of ecology and phenotypic diversity within a rapidly multiplying lineage as a result of speciation
—singlet common ancestor
—results in an array
—species differ in traits allowing exploitation of a range of habitats and resources
31
4 features of adaptive radiation
-recent common ancestry from a single species
-phenotype-environment correlation
-trait utility
-rapid speciation
32
Endemism
-Australia
—biological uniqueness as a result of its long history of isolation from other land masses
-endemism, radiation, and unique adaptations
33
Domestication
Example
Plant domestication
—teosinte and maize
—dogs
—pigeon
34
Evidence
-vast amounts of heritable variation found within species
-this variation can be selected on, leading to dramatic changes over generations
——artificial selection as the human imposed analog to natural selection in the wild
35
Variation, heredity, fitness
-individual variation in a population
-progeny resemble their parents more than unrelated individual
-some forms are more successful at surviving and breeding than others in a given environment
—-natural selection
36
Where does heritable variation come from?
-mutation
-independent assortment
-recombination
37
Mutation
-stable change in the DNA sequence
-occurs at a low rate
-different possible effects
-neutral
-deleterious
-beneficial
38
Characteristics of mutation
-mutation is an inevitable phenomenon
-Mutation is not directed towards an outcome by the organism or by the environment
-rate depends on a type of mutation
-environment can affect mutation rate
39
4 kinds of mutations
-point mutations
-insertion/deletions
-changes in repeat number
-chromosomal rearrangements
40
What is the rate of mutation?
-0.000000016 or 16 in every billion base pair
-approx. 96 new mutation per zygote
-every base pair in the genome mutated about 126 times over
41
Give an example of mutation that can be beneficial
Heterozygous
-G6PD deficiency in humans
-sever anemia
-protects against malaria
42
What is independent assortment
A process in meiosis
-the alleles of two different genes get sorted into gametes independently of one another
Generates diversity
43
Independent assortment in segregation during meiosis generate diversity how
Numbers
-allows different combinations of parent chromosomes
-2^2x2^2=16 possible zygote combination
-humans: 23 sets of chromosomes
-2^23=8.4 million different combinations
44
Recombination contributs…
-further contributed to variation
45
Heredity before Mendel
-organisms resemble their parents
-preformationism
-spermists/ovists believed only one parent contributed to inheritance
-theory of blending inheritance
-postulated that factors from both parents mix together irreversibly
-what happens to new mutations
46
Mendel’s predictions v experiment
Blending inheritance
-yellow and green make pale green
Actual result
-mix of yellow and green
47
Pea plant conclusions (4)
-inheritance is determined by discrete particles
-genes
-each diploid chromosome Carrie’s two copies of each gene
-alleles can exhibit dominance/recessivity
-Gametes fuses to make offspring
-sperm/pollen with egg/ovum
-gametes contain only one allele per gene
-offspring inherit one gamete from each parent at random
-one allele per gene at random from each parent
48
Discrete vs continuous terms
Discrete, discontinuous
Continuous, complex, quantitative
49
Foundations of population genetics
Summarize development as a field
1920-1950
Mathematical evolutionary theory for population genetic change
-Fisher, haldane, and wright
-foundation for neo-Darwinism and new synthesis
-continuous variation and Darwinian natural selection are entirely consistent with Mendel’s laws
-Demonstrated the evolutionary significance of genetic variation
50
What factors influence patterns of genetic diversity and evolution?
(5)
-mutation
-recombination
-random genetic drift
-natural selection
-negative (purifying) selection
-positive (directional) selection (adaptation)
-selection favouring diversity (heterozygous advantage)
-migration
51
Name the five processes of evolution and whether they increase of decrease genetic diversity
-mutation -up
-recombination -up
Genetic drift-up and down
-natural selection -up and down
-migration -up
52
Metrics in genetic variation
Heterozygous (H)
-fraction of individuals that are heterozygous averaged across gene loci
Polymorphism (P)
-proportion of gene loci that have w or more alleles in the population
-a locus can be polymorphic without being heterozygous
53
What maintains genetic variation?
1. Mutation-selection balance
-less fit types reintroduced by mutation
-followed by selection acting to remove them
2. Selection maintaining variation
-heterozygous advantage
-frequency-dependent selection
-fitness varies in space or time
-umbrella term “balancing selection”
54
Classic school v balance school
Differ on how much genetic variation occurs in natural populations
-classic
-Morgan, muller
-negative selection
-low heterozygous
-low polymorphism
-wild type is normal genotype
-balance
-dobzhansky, ford
-heterozygous advantage
-high heterozygosity
-high polymorphism
-selective favours diversity
55
Genetic markers
Morphological: snail colour polymorphism
Cytological: chromosomes inversions
56
Early genetic evidence for genetic variation
-rather than focus on Mendelian discrete traits, focus on continuous polygenic traits
-selection experiments on different groups of organisms
-involves controlled breeding of individuals with particular traits for many generations
———-> artificial selection
57
Evolutionary responses to continuous traits demonstrate what
-from the fly and corn graphs
-existence of inheritable variation in fitness-related phenotypes
-due to many underlying genes
58
Electrophoresis revolution
Lewontin
-allozyme gel electrophoresis provided a way to ask:
-what proportion of genes are variable (P+H)
-answering it addresses a fundamental dispute between the classical and balance schools
-initiated large scale surveys of electrophoretic variation in enzymes & proteins in diverse organisms
59
What is protein electrophoresis
-measuring diversity at genes that encode enzymes & proteins
60
Advantages of studies of enzyme polymorphism (5)
-many loci can be examined
-can be used in nearly any organism
-loci co-dominant, heterozygous can be identified
-variation examined close to DNA level
-provides genetic marker loci for other studies
61
Results from first allozyme studies
-genetic variation is very high
-the balance school wins kinda
62
3 rules concluded from allozyme studies
1.mutation-selection balance
-less fit types maintained by repeated mutational input
2. Selection maintaining variation
-heterozygous advantage
-frequency-dependent selection
-fitness varies in space or time
3. Selectively neutral variation
-different types do not differ in their fitness relative to one another
-new mutations neither eliminated not retained by selection
63
Neutral selection
Most molecular variation may be selectively neutral
-negative selection rapidly eliminated detrimental mutations
-positive selection rapidly fixes beneficial mutations
-the only mutations left ti create genetic variation are selectively neutral
64
Corn dropped in genetic diversity from what
A consequence of population Bottleneck during domestication
65
Human genetic variation graph example
-humans show a loss of genetic variation with increasing distance from East Africa
-Reflects founder events as humans migrated from source populations
66
Make the reproductive modes graphic
-reproductive system: asexual v sexual
-sexual system: dioecious v hermaphrodite
-mating system under hermaphrodite: cross-fertilization v self-fertilization
67
Sexual v asexual reproduction
Sexual
-2 parents contribute genetic material to offspring
-meiotic, reproductive division to form gametes
-fusion of gametes
Asexual
-1 parent contributes genetic material
-no meiotic reproductive division
-offspring are genetic replicas (clones) of parents
68
What is special about water fleas:
Different reproductive systems occur in different environments
69
What cool about perennial plants?
Water Hyacinth
-reproduce through both sexual and asexual reproduction
70
The costs of sex
-time and energy to find and attract mates
-increased energetic costs of mating
-risk of predation and infection
-cost of producing males
-50% less genetic transmission
-break up of adaptive gene combinations
-segregation, recombination
71
Transmission bias
—favours asexuals in competition with females
—sexual females only contribute 50% of her gene copies to the next generation
72
Hypotheses for the advantage of sex
-bringing together favourable mutations
-eliminating harmful mutations
-benefits of genetic variation
-lottery models given environmental unpredictability
-spatially heterogeneous environments
-tangled bank hypothesis
-temporally heterogeneous environments
-red Queen hypothesis
73
Advantage of sex in evening primrose
Asexual oenothera have:
-more premature stop codon mutations
-higher rates of protein sequence evolution
-implies greater accumulation of deleterious mutations
74
What is spatial heterogeneity
Uneven distribution of various concentrations of each species with in an area
75
Three parts to the macroevolutionary history of asexuality
-asexuality by parthenogenesis:
-more common in invertebrates, rare in vertebrates
-asexuality by clonal propagation:
-much more common in plants
-few species are exclusively asexual
-asexual species are usually at the tips of phylogenies
-macro evolutionary pattern indicates higher extinction rate
-low chance of long-term evolutionary persistence \ -probably due to extremely low genetic variation & accumulation of deleterious mutations
76
Mystery of the Bdelloid rotifers:
-no sex for millions of years
-a rare case of ancient asexuality
-males are unknown
-species diversification has led to > 300 spp.
77
Mating patterns Two types of breeding
-mates are less closely related than random
=outbreeding
-mates are more closely related than random
=inbreeding
In practice there’s a continuum
78
Self fertilization vs outcrossing
Outcrossing:
-mating with someone else
-either by outbreeding or inbreeding
-fusion of gametes from 2 parents
-gametes derive from meiotic
Selfing (self-fertilization):
-mating with yourself
-most extreme from of inbreeding
-but NOT asexual reproduction
-fusion of gametes from 1 parent
-gametes derive from meiotic reductive division
79
What is conducive to inbreeding
-local population substructure enhances mating among relatives
-in small populations, even random mating can lead to mating among relatives
80
Interbreeding avoidance traits in flowering plants
-large, showy flowers attract pollinators
-timing offset between male and female reproduction
-pollen v ovule maturation within a flower
-when male vs fable flowers open
-diverse morphological and physiological mechanisms to avoid selfing
-self-incompatibility
-e.g. spacing of another and stigma
81
Interbreeding avoidance behaviours in animals
-dispersal by one sex
-delayed pair copulation
-extra pair copulation
-kin recognition and avoidance
82
Population genetic effects of inbreeding
-changes genotype frequencies
-increases homozygosity
-decreases heterozygosity (H)
-does not directly change allele frequencies
-does not change polymorphism (P)
83
Inbreeding depression
-leads to reduced what and favours what
-the reduction in fitness of inbred offspring compared to outcrossed offspring
-lower viability (survival)
-lower fertility (reproductive output)
-strong inbreeding depression disfavours inbred offspring
-thus favouring outcrossed mating systems
84
Genetic consequences of inbreeding
-genotypic frequencies changed
-heterozygosity (H) reduced by 50% per generation with self-fertilization
-competition between homozygous genotypes (selection) & genetic drift of small pop’ns can reduce P
-homozygosity for deleterious recessive alleles
-results in inbreeding depression
85
Inbreeding depression causes….
Reduced fitness
-one of the most common evolution transitions
-associated with extensive phenotypic evolution
-roughly 20% of plants and hermaphroditic animal are highly selfing
86
Explain selfing shepherd’s purse
Fgnfnfg
87
Selfing-short term v long term
-over the short term:
-if conditions are favourable selfing can spread via natural selection
-lack of reproduction assurance due to rarity of pollinators or mates
-transmission advantage from self + exported pollen
-low inbreeding depression
-BUT harmful effects of inbreeding depression encourage outcrossing
-Over the long term:
-selfing leads to low diversity and inefficient selection
-can drive higher extinction rates in selfing species
-macro evolutionary pattern of greater prevalence of outcrossing
88
Fitness:
Genetic contribution of individuals to next generation relative to others as a result of differences in viability and fertility
=Darwinian fitness
-a relative quantity, not absolute survival or offspring number
89
What are the three kinds of natural selection acting on alleles
Positive directional selection (adaptation), negative purifying selection, and variation maintaining selection [balancing]
90
What does a graph displaying the Polygenic phenotypic trait value over the frequency of phenotype in a population look like
It would look like a sloped hill that comes down on the other side
91
Describe what a graph would look like for stabilizing selection, directional selection, disruptive selection
A very tall hill, a hill moved slightly to the right, a flat hill with two bumps
92
Give an example of directional selection relevant to Darwin
On the beak size of Galapagos finches correlating to seed abundance for resource acquisition
93
Give an example of disruptive selection
Beak size in African finches
-Disruptive selection leads to treat divergence
-May lead to speciation
-Requires special heterogeneity or discrete resources
94
How to study adaptation
Monitor correlations of alleles or traits with environments over space and time
Analyze genomic diversity
Experimental manipulations in the field or lab
95
Give an example of evolution by pollution
-industrial melanism in peppered moths
Evolution of heavy metal tolerance in grass
96
Explain heavy tolerance in grass and the moths thing
-mine waste heavily polluted with heavy metals
-most mines less than 100 years old
-heavy metal tolerant genotypes occur at very low frequency in nearby uncontaminated pastures
-tolerant genotypes invade mine tailings from nearby pastures
-gene flow restricted
-alleles enabling tolerance maintained in mines
-repeated evolution of heavy metal tolerance
97
Explain G6PD deficiency in humans
-selected for frequency of A- where malaria is present
-otherwise B selected away from anemia
