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exam #1 Flashcards

1
Q

what was darwin’s contribution to science?

A

evolution

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2
Q

Identify and explain the phrase that Darwin used to explain ‘evolution’?

A

Origin of species by means of natural selection

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3
Q

Define evolution, invoking both the wide and narrow interpretations.

A

Broad: descent with modification
Narrow: change in the genetic composition of a population over generations, Happens to populations, not individuals

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4
Q

Describe the influence of Cuvier, Hutton, and Lyell on Darwin’s thinking.

A

Cuvier: study of vertebrate fossils, speculated catastrophism (opposed evolution)
Hutton: suspected gradualism
Lyell: principle of uniformitarianism

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5
Q

Describe Lamarck’s ideas about evolution. Why were they important at the time? How is Lamarckianism perceived today?

A

Lamarck was first to propose a mechanism for evolution. Proposed mechanisms: use and disuse, inheritance of acquired characters
thought people could pass on characteristics like acquired intelligence or athletics

Not perceived as accurate today

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6
Q

What influence did his voyage around the world in the Beagle have on Darwin’s thinking about evolution?

A

Observed adaptations (inherited characteristics or organisms that enhance their survival and reproduction in specific environments)

Perceived adaptions to the environment and observations of different species as closely related processes

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7
Q

What influence did Wallace have on Darwin?

A

Wallace sent a manuscript with similar conclusions so darwin published his findings so he could get there first lol

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8
Q

Contrast catastrophism and uniformitarianism.

A

catastrophism: changes were due to abrupt, large-scale events
uniformitarianism: changes due to gradual, long-lived, small-scale events.

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9
Q

Why are evolutionary relationships often depicted in the form of trees?

A

show ancestors and their descendants

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10
Q

What do ‘nodes’ represent in the context of phylogenies?

A

represent common ancestors

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11
Q

How do fossils of extinct species document the divergence of extant groups? Hint: remember the elephant example from Figure 22.8.

A

Can document important transitions ex: land to sea

show relatedness patterns between very different organisms

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12
Q

Differentiate between natural and artificial selection.

A

Natural: arises from environmental (selection) pressures from differences that already existed within the population

Artificial: humans

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13
Q

Explain how the field study on soapberry bugs (described in Fig. 22.13) illustrates the main concepts of natural selection.

A

When their food source changed (tree with smaller seed closer to on another), over a period of 35 years, the soapberry birds beaks got smaller

Not a speciation event, simply, having a longer beak wasn’t an advantage like it used to be so it wasn’t selected for anymore

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14
Q

How does the rise of MRSA constitute a direct observation of evolutionary change? Refer to Figure 22.14.

A

Antibiotic resistance build-up

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15
Q

Explain two lines of evidence supporting a closer evolutionary relationship between Crocodiles and Birds compared to Mammals and Crocodiles – refer to Figure 22.17.

A

Because crocodiles and birds are only one common ancestor away from each other whereas mammals and crocodiles are 2

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16
Q

Explain how fossil evidence supports the idea that cetaceans evolved from terrestrial mammals.

A
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17
Q

According to the study of biogeography, why would one predict that the oldest horse fossils should be found in North America?

A

Because of pangaea and then divergence - different selection processes due to drift

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18
Q

Is natural selection ever ‘random’? Explain.

A
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19
Q

Explain why two organisms having similar appearances IS NOT evidence of common ancestry.

A

Convergent evolution
Some traits can come about independently ex; sugar gliders and flying squirrels have homologous features but came about by convergent evolution, not divergent evolution *two different places just thought it was a good idea

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20
Q

How is a phylogeny representative of the processes of unity and diversity as they relate to evolution?

A
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21
Q

which of the following is the most accurate summary of Cuvier’s consideration of fossils found in the vicinity of Paris?
a) extinction of species yes; evolution of new species yes
b) extinction of species no; evolution of new species yes
c) extinction of species yes; evolution of new species no
d) extinction of species no; evolution of new species no

A

c) extinction of species yes; evolution of new species no

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22
Q

what is molecular systematics

A

study of evolutionary relationships between organisms using molecular genetics

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23
Q

What is gene duplication? What are gene families? How are these important in molecular
systematics?

A

gene duplication: when genes are copies
gene families: when multiple gene duplications are grouped together

they provide valuable information about evolutionary relationships between species by comparing the variations within these gene families across different organisms

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24
Q

What are orthologous genes?

A

single copy in genome occurs after a speciation event

ex: cats and dogs have the same gene that was present in a common ancestor

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25
What are paralogous genes? what are the two opposing reasons they're important?
multiple copies of a gene within one species functional redundancy: serves as a back-up copy of the parental gene evolution of new functions: allows genes to still evolve (no selection pressure so genes can mutate)
26
Are gene number and the complexity of an organism linked? Why or why not?
No (ex: humans only have 4x the amount than yeast)
27
What is a molecular clock?
the explanation that some DNA sequences accumulate mutations over time like the steady clicking of a clock
28
. How does genetic drift affect the workings of a molecular clock? How about natural selection?
molecular clocks cannot be at a constant rate if genes are under natural selection genetic drift would speed up the clock since the likelihood for mutations to reach fixation would be higher
29
Explain Motoo Kimura’s neutral theory of evolution. What is the significance of this theory for molecular systematics?
if a mutation has no effect on fitness, its fate in the population is determined completely by chance most mutations are neutral which means they can help hypothesize where phylogenies diverged
30
Discuss the major issues associated with using a molecular clock.
1. don't run as smoothly as expected when mutations are neutral 2. irregularities occur when natural selection occurs 3. estimates of evolutionary divergences have a high degree of uncertainty
31
Would you choose a non-coding or coding region to assess the evolutionary relationships between closely related taxa? Taxa that are not closely related? Explain.
introns (non-coding) evolve quickly and are not under the influence of natural selection whereas exons evolve slowly and are under the influence of natural selection closely related: non-coding to see more recent changes not closely related: coding to allow for reliable comparisons
32
for both orthologous and paralogous genes, nucleotide substitutions are proportional to the time since a) ancestral gene was duplicated or b) they last shared a common ancestor ?
orthologous genes: they last shared a common ancestor paralogous genes: ancestral gene was duplicated
33
changes to ribosomal/mitochondrial/intron/exon genes occur slowly/rapidly
ribosomal: slowly mitochondrial: rapidly intron: rapidly exon: slowly
34
What are the three main mechanisms of evolutionary change?
1. natural selection 2. genetic drift - bottleneck effect - founder effect 3. gene flow
35
What is the Modern Synthesis? Why is it important?
population genetics, sets the stage for several disciplines in evolutionary biology
36
Describe notions of blended inheritance and the inheritance of acquired characters.
Blended inheritance: the idea that if there was a tall father and short mother, offspring would be average
37
Why doesn’t natural selection produce ‘perfect’ organisms?
38
What is Gregor Mendel’s contribution to genetics?
Demonstrated particulate inheritance -> traits are passed down, not inherited
39
Where does genetic variation come from?
mutation or gene duplication or sexual reproduction: can shuffle existing alleles into new combinations and can cause: crossing over, independent assortment of chromosomes, fertilization
40
How would a point mutation FAIL to change the effect of natural selection on an organism?
if it wasn't in the gamete
41
How is the Hardy-Weinberg Equation used to determine if a population is evolving?
First step: clarify what we mean by population If allele frequencies change, evolution can be seen as happening.. HW describes a population that is not evolving 1 = p+q (allele frequency) 1 = p^2 + 2pq + q^2 (genotype frequency)
42
define population and gene pool
Population: localized group of individuals capable of interbreeding and producing fertile offspring Gene pool: consists of all the alleles for all loci in a population
43
what are the five conditions for a non-evolving population
1. No mutations 2. Random mating 3. No natural selection 4. Extremely large population size 5. No gene flow
44
define genetic drift and gene flow
genetic drift: A process in which chance events cause unpredictable fluctuations in allele frequencies from one generation to the next, Most pronounced in small populations gene flow: Movement of alleles among populations
45
what's founder effect and bottleneck effect
Founder effect: a small proportion of individuals in a population get separated from the rest of the population, Only a few random individuals are isolated – creates new populations with different allele frequencies Bottleneck effect: only a few members of a population survive, Not reflective of the original populations genetic makeup
46
Explain how genetic drift could lead to allele fixation. How would this affect the evolutionary mechanism of natural selection?
Genetic drift is expected to lead to a decrease in genetic variation within a population, eventually some alleles may be lost and others fixed Fixed: all alleles in a population are the same
47
genetic drift/gene flow can cause greater/decline of allele differences between/within two/one population
genetic drift: greater allele difference between two different populations and decrease in genetic variation within a population gene flow: greater genetic variation within populations and decrease in allele differences between populations
48
Describe a situation where gene flow has benefitted a population.
- Can increase the fitness of a population through local adaptation - Can lead to the spread of beneficial alleles Ex: pesticide tolerant bugs can enter a new population and introduce their alleles
49
How does the phrase ‘Survival of the Fittest’ relate to the concept of ‘Relative Fitness’?
Relative fitness: contribution a genotype makes to the gene pool of the next generation (# offspring produced), relative to the contributions of other genotypes Selection acts to increase the frequency of alleles that confer a reproductive advantage
50
Compare and contrast the three general modes of selection.
Directional selection: Favours individuals at one end of the phenotypic range Disruptive selection: Favours individuals at both extremes of the phenotypic range Stabilising selection: Favours intermediate phenotypes and acts against extreme phenotypes
51
How does the concept of sexual selection ‘fit into’ the concept of natural selection, i.e. how are these processes similar? How are they different?
Sexual selection: natural selection for mating success Can result in sexual dimorphism: marked differences between the sexes in secondary sexual characteristics Certain inherited traits can increase the likelihood of obtaining mates
52
How do intra-and-intersexual selection differ? Provide an example of each.
Intrasexual selection: organisms of the same gender compete with each other for the opportunity to mate Ex: bighorn sheep battling Intersexual selection: the mate is chosen based on certain traits -> mate choice Female usually chooses based on males physical traits Male’s showiness can usually increase the chances of getting a mate, but if they stand out too much a predator might get them Can affect mate success, but also survival chances
53
Differentiate between heterozygote advantage and heterozygote protection.
Frequency dependent selection: the fitness of a phenotype declines if it becomes too common in a population Selection can favour whichever phenotype less common in a population Keeps the frequency of each phenotype close to 50% Heterozygote advantage: occurs when heterozygotes have a higher fitness than both homozygotes Natural selection will tend to maintain two or more alleles at the locus Ex: sickle cell distribution 1 allele of sickle cells can help fight against malaria 2 alleles cause sickle cell anemia
54
Describe the Biological Species Concept and explain the limitations associated with it.
Based on the potential to interbreed in nature Limitations: excludes asexual organisms since it relies on gene flow & Can’t be applied to fossils -> hard to tell from fossil record if genes are exchanged
55
Explain species concepts other than the BSC. What are some advantages and disadvantages associated with each species concept? SC -> species concept
Morphological SC: based on body form, physical traits + : can be applied to asexual species, don’t need gene flow information - : subjective criteria for defining species Ecological SC: based on niche that organism occupies How populations interact with living and non-living factors of their environment + : allows for some interbreeding, accommodates sexual and asexual reproduction Lineage/phylogenetic SC: based on shared pattern of ancestry or descent + : asexual and sexual reproduction, can apply to fossil record
56
Describe prezygotic and postzygotic barriers to gene flow and give specific examples of each.
Prezygotic barriers: impede species from attempting to mate with one another, or successful fertilization - Habitat isolation: different habitats Ex: insects on leaves vs roots -Temporal isolation: time Ex: breed at different times of day, year, etc., -Behavioural isolation: unique behaviours -Mechanical isolation: body form of two species prevent mating -Gametic isolation: gametes are not compatible Ex: sperm lacks characteristics to penetrate egg Postzygotic barriers: prevent hybrid zygote from developing into a fertile adult - Reduced hybrid viability: doesn’t develop into a viable, fertile adult - Reduced hybrid fertility: viable adult forms but cannot reproduce, sterile - Hybrid breakdown: viability of hybrids breakdown over generations Ex: first generation hybrid, and hybrid to hybrid mating -> viability breaks down
57
What is sympatric speciation? Explain an example
takes place in geographically overlapping populations ex: habitat differentiation -> occupying different niches
58
What is allopatric speciation? Explain an example
Dependent on a geographical barrier Ex: a canyon can be a barrier for a rodent but not for a bird
59
What is polyploidy? How does polyploidy relate to speciation?
Presence of extra chromosome sets due to accidents in cell division More common in plants than animals New species can be produced in a single generation due to polyploidy
60
What is an autopolyploid? What is an allopolyploid?
autopolyploid: Polyploidy with an extra set of chromosomes from one species allopolyploid: Polyploidy with an extra set of chromosomes from more than one species
61
What is homology?
similarity due to shared ancestry
62
what is analogy?
similarity due to convergent evolution
63
What is convergent evolution? What causes it?
Convergent evolution: occurs when similar environmental pressures and natural selection produce similar (analogous) adaptations in organisms from different evolutionary lineages
64
How do we recognize homology?
comparing fossil evidence and degree of complexity
65
what is homoplasy?
analogous structures that evolved independently
66
Put these in order from least to most inclusive: Class, Genus, Family, Domain, Phylum, Class, Kingdom, Order, Species.
domain (most inclusive), kingdom, phylum, class, order, family, genus, species (least inclusive)
67
What is a branch point?
Divergence of two species, Common ancestor, Also called a node
68
What are sister taxa?
Two groups that originate from one branching point and are at the tip of the tree, Share an immediate common ancestor
69
What is a rooted tree?
Includes a branch to represent the last common ancestor of all the taxa in the tree
70
what is a polytomy
more than two common ancestors emerged from a point
71
What can we learn from phylogenetic trees? What can’t we learn?
Do not indicate when species evolved or how much change occurred in a lineage Do not indicate that a taxon evolved from the taxon next to it
72
There are many possible ‘candidate’ evolutionary trees for any given group of species. How do we tell which is the right one?
By using Cladistics: a method to infer phylogeny and find the right tree - Approach to systematics: discipline of classifying organisms and finding their evolutionary relationships - Members of a group are more closely related to members of the same group than to members of another group Maximum parsimony: the assumption that evolution proceeds by a smaller, rather than a larger, number of events
73
What is the role of shared, derived homologies?
to group taxa non-ancestral, changed or apomorphic traits
74
What is a shared, ancestral character called?
symplesiomorphy, Present in the ancestor, Shared between all the taxa
75
What is meant by ‘polarizing characters’?
Apomorphic character Can be used to create clades
76
Explain monophyly, paraphyly, and polyphyly. Ideally, should taxa be monophyletic, paraphyletic, or polyphyletic? Why?
Monophyletic: consists of a ancestral species and all of its descendants - Only group classified as a clade Paraphyletic: consists of an ancestral species and some of its descendants Polyphyletic: consists of various species with different ancestors Ideally, taxa should be monophyletic
77
define synapomorphies
apomorphy, shared derived homology
78
define symplesiomorphies
shared ancestral homologies present in common ancesto
79
define cladogram and phylogram
Cladogram: depict evolutionary history only (branching only) - Can be displayed many ways without affecting interpretation Phylogram: depict evolutionary history but the branch length means something - Time scale can be associated with branch lengths (ex)
80

biol 1020 (3 decks)

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