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BIOL 302 - Evolution > post midterm > Flashcards

post midterm Flashcards

1
Q

Two definitions of adaptation

A
  • characteristics that enhance the survival or reproductive success of organisms that bear it relative to other stages
  • process of genetic change in a population whereby as a result of nat sec the average state of the character is altered (the population becomes better adapted to their environment
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2
Q

What is the adaptationist fallacy?

A

evolutionary biologists had a habit of proposing adaptive explanations for any trait by default without considering non-adaptive alternatives, and often by conflating products of adaptation with the process of natural selection
changes in organisms are not always adaptations - neutral theory

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3
Q

For it to be considered an adaptation it must increase _____

A

fitness

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4
Q

Adaptations produce more ____ individuals

A

complex

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5
Q

selection ____ towards complexity, genetic drift ____

A

does, does not

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6
Q

3 ways to recognize adaptations

A

By the complexity and design
By an experiment
By the comparative method which requires lots of evidence and to be phylogenetically informed

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7
Q

Define Exaptation

A
  • the evolution of a function of a gene, tissue or structure other than the one it was originally adapted for. Can also refer to the adaptive use of a previously nonadaptive trait
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8
Q

Define directional selection

A
  • selection for a value that is higher or lower than its current mean value
  • often produced by sexual selection
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9
Q

Define stabilizing selection

A

selection that maintains the mean of a character at or near a constant intermediate value in a population

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10
Q

Define disruptive selection

A

Selection in favour of two or more phenotypes against the intermediate - diversifying selection

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11
Q

Mean fitness ___ with successive generations of selection (as the allele with lower fitness is purged from the population

A

increases

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12
Q

What is the cost of adaptation?

A

Cost penalty of adapted individuals in a changing environment
- rats resistance to pesticides decreasing fitness after pesticides no longer present

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13
Q

What is the common trend among pesticide resistance?

A

generally based on single mutations of large effect and gene for resistance is at least partially dominant

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14
Q

Antagonistic selection can lead to ___ ___ ___

A

antagonistic niche polymorphism

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15
Q

Antagonistic selection can be due to ___ or ___, define these terms

A

Temporal fluctuation - environments favor different genotypes across generation

Spatial fluctuation - different genotypes are best adapted to different microhabitats or resources

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16
Q

Heterozygote advantage is _____ selection

A

stabilizing

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17
Q

Heterozygote disadvantage can lead to:

A

fixation of one of the alleles - can lead to a population with fitness slightly less than theoretically possible

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18
Q

Define antagonistic selection - provide an example

A

When one selection force opposes a different selection force

  • Sickle cell anemia - anemic with A2A2, at risk for malaria with A1A1 - Heterozygote is a middle phenotype
  • this is actually a bad example - diversifying selection is better - big males v small females - selecting for opposite traits
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19
Q

Negative frequency dependent selection means it is beneficial to be the _____ geno/phenotype

A

rare

  • parasitic fish favoring a side - favor the side that less fish pick = more food 4 u
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20
Q

Define positive frequency dependent selection

A

the fitness of a genotype is greater the more frequent it is in a population

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21
Q

What is Mullerian mimicry?

A

two or more unpalatable species mimic eachothers warning colorations

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22
Q

Define Cline

A

a gradual change or gradient in an allele frequency or in the mean character trait over a geographic transect.

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23
Q

What is the breeders equation - define the variables

A

R = h^2S
R = response to selection
h^2 = heritability estimate of trait
S = selection on the trait

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24
Q

Define correlated selection

A

selection favours certain combinations of traits over others
- ex) spotted vs striped coloration and escape behaviour in garter snacks
(either is easier to see and flees or harder to see and stays put)

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25
Q

Define and provide the equation for broad scale heritability

A

an estimate of the proportion of phenotypic variance with a genetic basis BUT does not give an accurate reflection of the AMOUNT that wil be transmitted across generation
H^2 = Vg/ Vp

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26
Q

Define narrow scale heritability

A

an estimate of the proportion of phenotypic variance with an ADDITIVE genetic basis
WILL give an accurate reflection of the amount that will be transmitted between generations

27
Q

What are the six causes of linkage disequilibrium?

A

Non random mating
New mutations
Union of two populations
Low/ negligible recombination
Genetic drift
Natural selection

28
Q

Define life history

A

Age specific probabilities of survival and reproduction in a population

29
Q

Define semelparity?

A

Reproductive strategy in which an organism produces all of its offspring in a single event

30
Q

Define iteroparity?

A

reproductive strategy in which an organism produces offspring across multiple events

31
Q

Age specific patterns of survival and reproduction in a population are depicted in a ____

A

life table

32
Q

define senescence

A

declining reproduction/ physiological condition with age

33
Q

Two leading theories on why we age?q

A
  • mutation accumulation with age
  • antagonistic pleiotropy
34
Q

Explain the idea of mutation accumulation with age?

A

selection will more effectively purge deleterious mutations affecting early life traits than those affecting late life traits. - Therefore mutations affecting late life traits accumulate

35
Q

Explain antagonistic pleiotropy

A

an allele that has a beneficial effect on one trait ( early life reproduction ) has a detrimental affect on another trait ( late life reproduction)

36
Q

What are life history trade offs?

A

The existence of both a fitness advantage and a concurrent fitness cost
- survival/ reproduction trade offs
- early reproduction/ late reproduction trade offs
- offspring quality/ quantity trade offs

37
Q

What causes life history trade offs?

A

physiological constraints and negative genetic correlations

38
Q

Due to physiological constraints, selection should favor ____ in a given environment>

A

optimal life history traits

39
Q

Are physiological constraints and negative genetic correlations mutually exclusive??

A

nope

40
Q

Define outcrossing?

A

mating with another, genetically distinct individuals

41
Q

define self fertilization?

A

union of female and male gametes produced by the same genetic individual

42
Q

Define anisogamy

A

distinct male and female sexes, defined by gamete size

43
Q

Define isogamy

A

uniting cells are the same size - unicellular or colonial organisms

44
Q

Define dioecious

A

distinct male and female individuals within a species

45
Q

Define hermaphroditic?

A

male and female sexual functions are performed by a single individual - worms, trees etc

46
Q

Define sequential hermaphroditism?

A

organisms that change sex over the course of their lifespan like annelid worms

47
Q

Define vegetative propagation

A

production of offspring from somatic tissue

48
Q

Define parthenogenesis

A

development from an egg to which there has been no paternal contribution of genes - virgin birth
- apomixis - meiosis suppression - individual develops from mitotic cells
- offspring is genetically identical to its mother

49
Q

What are the pros and cons of sexual and asexual reproduction?

A

Asexual reproduction is fast, energetically efficient, no partner needed and every individual in the population can reproduce however there is a stark lack of genetic diversity as offspring are identical to the mother - effectively the reverse is true for sexual reproduction

50
Q

Three hypothesis for the evolution of sexual reproductive systems

A
  1. sexual reproduction combines new mutations or rare alleles to create new potentially advantageous phenotypes
  2. adaptation to varying environments (including parasite pressure) - recombination breaks down linkage disequilibrium and can result in rare genotypes
  3. separating beneficial vs harmful mutations
51
Q

What is a mutational meltdown?

A

mutations in an asexual population will accumulate through generations and ultimately lead to a mutational meltdown or an accelerated loss of fitness

52
Q

What is Mullers ratchet?

A
  • In an asexual population there is a range of genotypes carrying x mutations
  • more fit genotypes can be lost by chance due to genetic drift
  • offspring always carry a greater number of mutations than their ancestors
  • mutations will accumulate leading to a mutation meltdown

(remember, generally mutations are bad)

53
Q

What is the Hill-Robertson effect

A

if
a mutates to A and A has higher fitness
b mutates to B and B has higher fitness
then without recombination A is in linkage disequilibrium with b and B is in linkage disequilibrium with a

Without recombination beneficial alleles can be lost due to linkage disequilibrium with deleterious alleles

54
Q

Two ideas of the reality of species?

A

Nominalism - idea that species are artificial divisions of a natural continuum

Realism - idea that nature is, in fact, divided into discrete species.

55
Q

define species from an evolutionary perspective

A

real units in nature that represent an independently evolving lineage

56
Q

Two categories of species concepts

A

Horizontal - aim to define species at an instant in time and specify which individuals belong to which species at one time

Vertical - aims to define species through time and specify which individuals belong to which species through all time - ex dinosaurs - measuring and recording from a diff time

57
Q

Two versions of the phenetic species concept?

A

classic - typological species concept - individuals belong to a species if they share characteristics with the type specimen

modern - statistical techniques for describing phenetic similarity

58
Q

What is the biological definition of species?

A

species are groups of actually or potentially interbreeding populations which are reproductively isolated from other groups
- lack of gene exchange between two species due to biological not geographic factors

59
Q

Define reproductive isolation

A

lack of gene exchange between two sepceis due to biological not geographic factors

60
Q

Three stages of speciation?

A
  1. Population Isolation
    - reduction in gene flow between populations
    - commonly due to geographic separation
    - could be due to other factors
  2. Divergence
    - in morphology, habitat use, mating habits, niche
  3. Reproductive Isolation
    - following secondary contact (when populations come back together)
61
Q

Four general kinds of speciation?

A

Allopatric speciation by vicariance (barrier/ split in population) - most common

Peripatric speciation - founder effects - strong genetic drift

Parapatric speciation - large range with different habitats but not isolated - slow acting

Sympatric speciation - genetic differences resulting in reproductive isolation - slowest acting

62
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A
63
Q
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BIOL 302 - Evolution (6 decks)

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