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BIEB 150 > Final > Flashcards

Final Flashcards

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1
Q

Explain each of Darwin’s 4 postulates.

A

Genetic variation

Overproduction

Competition

Favorable trait that increases survival + reproduction

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2
Q

Discuss how together the 4 postulates result in a shift in the traits of a population between generations.

A

Overproduction leads to competition for limited resources, which creates selective pressures. When certain heritable traits provide a survival advantage, those traits become more common in the pop over time, especially if there is enough genetic variation for natural selection to act upon. This process results in a shift in traits as advantageous characteristics are passed on to future generations.

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3
Q

Based on the postulates explain how natural selection could fail to result in evolution. 3 points

A

Nat sel could fail to result in evol if…

(1) there is little to no genetic variation for nat sel to act upon. E.g small pops

(2) the trait is non-heritable

(3) there is a lack of competition as there is no challenges in survival meaning the presence or absence of certain traits may NOT impact survival/reproduction

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4
Q

Explain the different types of mutations.

6 total + causation

A
  1. Point muts → silent; missense (change in aa); nonsense (early stop codon)
  2. Indels → frameshift
  3. Inversions → suppressed recom
  4. Duplications → neo/subfunctionalization
  5. Aneu/polyploid → replication error
  6. Chromo fusion
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5
Q

Explain how gene duplications can facilitate rapid evolution of new function. Define the 2 terms

A

via Neo/sub functionalization

Neo - 1 copy evolves a new function; other retains og function

Sub - share og function w/ independent ne functions

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6
Q

Differentiate synonymous from non-synonymous mutations and germline from somatic mutations.

A

Synonymous → no aa change
vs.
Nonsynonymous/missense → aa change

Germline → muts in eggs/sperm; heritable
vs.
Somatic muts →muts in body cells; not heritable

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7
Q

Explain the difference between different modes of inheritance (ways by which cell division occurs)

2 modes

A

Sexual - segregation during meiosis; recombination during crossing over, creating new allele combos); increases genetic variation

Asexual - genetic clone; no recomb; no meiosis; no genetic variation

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8
Q

Explain how meiosis contributes to variation in allele frequencies.

A

indirectly via segregation - the separation of homologous chromosomes where each gamete gets a random combination of maternal + paternal alleles

Segregation introduces variation but doesn’t directly alter allele frequencies in a pop at large, assuming random mating + no other evolutionary forces

In smaller groups, random outcomes from segregation + fertilization can cause allele frequencies to shift

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9
Q

Understand what to use to calculate the expected genotype and allele frequencies under Hardy-Weinberg.

e.i. what #s go where? refer to orange notebook

A
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10
Q

Detect deviations in empirical data and interpret what it means for HW

A

expected vs observed

expected = observed, then evol is occurring

expected DOES NOT = observed, then evol is NOT occurring

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11
Q

what are the assumptions of Hardy–Weinberg equilibrium? 5 total

A

(1) random mating
(2) large population
(3) No muts
(4) No gene flow
(5) No nat sel

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12
Q

Explain dominance

A

when 1 allele wins over the other, affecting pheno

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13
Q

Explain epistasis

A

when 1 gene impacts another, affecting pheno

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14
Q

Explain pleiotropy

A

one gene impacts expression of multiple traits, changing pheno

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15
Q

Explain plasticity

A

a certain environment impacts gene expression, changing phenotype

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16
Q

Explain how fitness relates to natural selection. define fitness

A

natural selection favors organisms w/ higher fitness while acting to remove those w/ lower fitness

fitness - an organism’s ability to survive + reproduce in its environment

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17
Q

Explain how differences in fitness result in evolutionary change.

A

Organisms w/ higher fitness are more likely to survive + reproduce due to their adaptations to the environment

Over time, accumulation of beneficial traits in individuals w/ higher fitness leads to evolutionary change given said traits are to be passed down more frequently

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18
Q

Distinguish between absolute and relative fitness.

A

Absolute: expected # of offsprings produced

Relative: observed. # of offsprings produced

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19
Q

Describe the different fitness components. 4 total

A

Viability - organism’s ability to survive to reproductive age

Fecundity - how many offspring produced

Mating success + Fertility success

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20
Q

Define a selection coefficient and understand what it means

A

Measures strength of nat sel acting on allele; Used to compare relative
FITNESS of different genotypes

  • SC = 0, NO selective dis/advantage
  • SC > 1, selective advantage
  • SC < 1, selective disadvantage
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21
Q

Calculate the change in allele frequency based on strength of selection + starting frequency

A
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22
Q

Explain how heterozygote advantage and frequency-dependent selection can maintain genetic variation. Define both terms

A

Heterozygote advantage → favors the heterozygous genotype
Freq-dependent sel → increases rare alleles

mechanisms ensure that diff alleles are maintained in the pop, preventing the loss of genetic diversity

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23
Q

Explain mutation-selection balance.

A

equilibrium between the rate at which new muts arise in a pop and the rate at which they are removed by natural selection

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24
Q

Define migration (from an evolutionary vs. ecological perspective) and explain its effect on allele frequency.

A

Migration evol = gene flow
—-> Introduces new alleles into a pop, potentially increasing genetic variation

Migration ecol = seasonal or regular movement of individuals or species from one area to another
—-> indirect effects on allele freq

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25
Describe the island model, as well as the basic population genetic equations associated w/ gene flow in this model.
genetics model used to describe effects of gene flow between several pops that are INITIALLY SIMILAR but may experience genetic differentiation due to migration and local selection IDK THE EQUATION
26
Discuss why the strength of selection is important relative to amount of gene flow. aka high vs low migration rates
High migration rate = homogenizes pops Low migration rate = high differentiation
27
(Q3) Define genetic drift.
a mech of evol based on random chance, not adaptive, significant in smaller pops, can lead to fixation (just like nat sel), and can cause alleles to diverge
28
Understand how genetic drift is different from the other mechanisms of evolution.
genetic drift is based on pure chance that depends on pop size
29
Differentiate between continuous drift, the founder effect and population bottlenecks CHECK LITTLE NOTEBOOK
continuous - always happening; small changes founder effect - bottlenecks -
30
Explain the effect of genetic drift on heterozygosity
31
Define effective population size.
32
Explain how drift and selection interact
33
Contrast random and non-random mating.
34
Explain why inbreeding can produce offspring with obvious deleterious phenotypes.
35
Explain how phenotypic variance is partitioned
36
Describe the importance of genetic variance and how it contributes to our understanding of heritability
37
Understand how heritability is calculated according to parent offspring regression.
38
Explain the concept of an adaptive landscape
39
Explain the mechanisms through which maladaptation arises.
40
Recognize a pattern of adaptation or maladaptation from experimental, observational, or comparative data
41
define the types of adaptation patterns via (1) Experimental Observations (2) Clinal Variation (3) Comparative Method
42
Recognize a pattern of character displacement and explain why it evolves. Explain the assumptions and predictions for character displacement.
43
Differentiate between Batesian and Mullerian mimicry.
44
Explain how the evolution of Batesian and Mullerian mimicry would be favored by natural selection.
45
Explain what an arms race is and be able to recognize the phenotypic pattern.
46
Discuss why reduced virulence is hypothesized to evolve, and why it might not actually evolve.
47
Contrast sexual and natural selection.
48
Compare and contrast the asymmetries in sexual reproduction between females and males.
F → always invest more in gametes and parental care; Limited by resource availability; Allowed to be choosy M → invest less in gametes; limited by female availably
49
Differentiate between intrasexual and intersexual selection
Intra: M-F competition - allows females (exceptions) to be choosey based on traits of opposite sex Inter: M-M competition for F; Competition within 1 sex
50
List and recognize the different forms of intrasexual selection and provide examples of each type. 3 total
Premating - Physical combat, displays, territorial defense Postmating/prezygotic - Cryptic female choice: sperm storage Postzygotic - infanticide
51
Discuss the various hypotheses for why females can be choosy about their mates. direct + indirect benefits
Direct benefits: nuptial gifts, parental care - increased fecundity (ability to produce offspring) or survival Indirect benefits ---->Sexy sons: increased mating success for their sons Meaning increased reproductive success (more offspring) ---->Good genes: increased survival and reproductive success (fitness) for their offsprings
52
Define a species and understand how biologists classify them. Compare four different species concepts and their application. 4 total
BSC: A species is a group of organisms that can interbreed and produce fertile offspring, and are reproductively isolated from other such groups Morphological: species are defined based on physical characteristics or morphological traits. Genetic: Species are defined based on genetic divergence between pops. Evolutionary: A species is defined by its ecological niche—the role it plays in the ecosystem, including its habitat, diet, and interactions with other species
53
Differentiate between the different types of isolating barriers. 2 total, each w/ 3 subcategories
Prezygotic ----> Temporal --------> Behavioral --------------> Isolation Postzygotic ----> Hybrid inviability - stillborn; Possibly due to diff chromo # --------> Hybrid infertility - evol reaches a dead end --------------> Hybrid breakdown visible only in F2 gens
54
Explain the different geographic contexts of speciation. 4 total
Allopatric Speciation: Speciation that occurs when pops are geographically isolated from each other, preventing gene flow between them ---->Natural selection, genetic drift, mut Sympatric Speciation: Speciation that occurs w/o geographic isolation, where pops diverge while living in the same area ----> Ecological specialization, sexual selection, polyploidy Parapatric Speciation: Speciation that occurs when pops are PARTIALLY separated by an environmental gradient or occupy adjacent but non-overlapping regions, w/ limited gene flow between them ---->Local adaptation, assortative mating Peripatric Speciation: A special case of allopatric speciation, occurring when a small pops becomes isolated at the edge of a larger pops range ----> Genetic drift, founder effects
55
Explain how speciation can occur in sympatry. define sympatry
Sympatric speciation → when there is NO geographic isolation processes create reproductive isolation within a single geographic area, allowing pops to diverge into separate species
56
Explain how Dobzhansky-Muller incompatibilities lead to reproductive isolation.
accumulation of DMIs means that hybrids are less fit or unable to survive/reproduce, which reinforces reproductive isolation between pops
57
Define Haldane’s rule.
Heterogametic sex (thoes w/ 2 sex chromosomes) highly affected such that its inviable or sterile
58
Explain the different outcomes of hybridization. 5 TOTAL
Reinforcement: selection strengthens reproductive barriers to prevent hybridization Stability: Stable hybrid zones - hybrids consistently produced but selected against (tension zone) Fusion: Lineage fusion - 2 pops/species merge back into a single population or species Introgression: unidirectional - hybrids backcrossing w/ 1 parental species Hybrid speciation: speciation by hybridization - Hybrids form a new, distinct species that is reproductively isolated from the parent species
59
Recognize example of reinforcement and understand the concept
where nat sel strengthens prezygotic barriers, avoiding maladaptive hybridization EX) mate choice, timing of reproduction
60
Distinguish between microevolutionary and macroevolutionary patterns/processes.
MICRO - gradual, constant change in allele freq within a pop’s gene pool ----> Occurs within a single pop/species ----> Results in adaptation ----> via nat sel, muts, drift MACRO - bursts of changes ----> Occur over long geological time periods ----> Results in speciation/diversification ---->via adaptive radiation, extinction, convergent evolution, and large-scale environmental changes
61
Explain the difference between gradualism and punctuated equilibrium.
gradualism - gradual evol changes punctuated - rapid burts of evol changes with long periods of stasis
62
Understand how speciation and extinction rates contribute to diversification rates and how they can vary over time.
Speciation rate increases diversity by creating new species Extinction rate reduces diversity by removing species vary over time bc of environmental changes, ecological factors, and evolutionary processes
63
Explain how ecological opportunity can lead to diversification.
diversification is possible bc the individuals could possibly diversify to try and fill up a niche made available also known as ecological opportunities - relates to adaptive radiation
64
Differentiate between the different types of ecological opportunity and recognize examples of each. 4 total
habitat - availability of new physical spaces resource - availability of new resources biological - changes in biological interaction aka coevol + symbiosis ecological - availability of new niches or resources within an ecosystem that allow organisms to exploit unfilled or underutilized environmental roles
65
Recognize a pattern of competitive displacement. OUTCOMPETES; BECOMES THE competitor
when one species outcompetes another for resources, causing the displaced species to either reduce its pop, leading to possible extinction 1 species wins, other loses
66
Distinguish between and adaptive and non-adaptive radiation
Adaptive - when a SINGLE ancestor species diversifies into MULTIPLE species, each adapted to exploit different ecological niches ----> nonrandom ----> driven by nat sel Non-adaptive radiation - species evolve w/o a need for ecological adaptations ----> random ----> driven by genetic drift + founder effects

BIEB 150 (2 decks)

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