Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

Evolution 355 > midterm #2 > Flashcards

midterm #2 Flashcards

(65 cards)

Start Studying
1
Q

dispersal: which individuals establish new colonies

A

furthest-moving individuals most likely to expand range or establish new populations,

but also hardest to track

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

favouring high or low dispersal ability

A

high dispersal ability:

  • colonizing species
  • species in variable environments
  • species subject to directional change in environment

low dispersal ability:

  • species in stable environments
  • species in isolated patches of favourable habitat
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

island evidence of dispersal ability (3)

A
  • islands are usually colonized by highly dispersive organisms
  • often closely related to mainland taxa, retain some traits
  • often have low dispersal opportunities, so many species end up being low-dispersal (isolated favourable habitat)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

climate change and dispersal ability (5 kinds)

A

1) distribution shift
- species just track their preferred habitat toward poles altogether

2) range expansion by adaptation
- populations who can adapt may expand their range

3) habitat decline
- dispersal ability, but the available habitat declines

4) dispersal barrier
- geographic barrier may prevent range expansion

5) limited dispersal ability
- just not being able to disperse, no adaptation

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

what limits species ranges? (3)

A
  1. obvious geographic barriers
  2. lack of genetic variation. not enough favourable alleles to select from
  3. gene flow from other populations with non-locally-adapted alleles
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

criteria used for establishing species (3)

+ problem

A
  • reproductive isolation
  • morphological divergence
  • genetic divergence

problem: often don’t give the same groups

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

biological species concept

+ problem cases

A

group of interbreeding individuals, reproductively isolated from other species

problem cases:

  • asexual species (all non-eukaryote species)
  • self-fertilizing species
  • fossils (no way to infer)
  • allopatric species with non-overlapping ranges
  • hybridizing species
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

taxonomic species concept

A

group of individuals with overall similarity of phenotype (resemble one another more than members of other groups)

  • practical and useful for first estimates
  • requires no knowledge of phylogenetic relationships
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

phylogenetic species concept

A

cluster of individuals connected by ancestor-descendant relationships, diagnosable molecular differences from other clusters

  • requires knowledge of phylogeentic relationships, duh
  • allows assigning allopatric populations to same species
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

heritability

A

variation in a trait due to additive genetic variance

- between 0 and 1

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

narrow-sense heritability:

  • formula
  • if 0, if 1
  • regression line
A

h^2 = additive genetic variance/total variance

if 1: offspring strongly resemble parents
if 0: offspring don’t resemble parents more than any other random adult

  • slope of regression line in offspring/mean of parents indicates heritability
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

breeder’s equation

A

R = h^2 x S

R: response to selection
- mean trait difference between parent and offspring generations

S: selection differential
- trait difference between entire parent generation and those selected as parents for the next

h^2: heritability

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

constraints on (artificial) selection (4)

A
  1. lack of genetic variation
  2. opposing selection pressures (trait can only go one way)
  3. linkage disequilibrium
  4. correlated evolution (due to pleiotropy)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

linkage disequilibrium
+ 2 possible reasons
+ recombination

A

non-random association of alleles at different loci

1) physical linkage on same chromosome (most often)
2) evolutionary processes affecting allele combinations

  • declines over time because of recombination
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

QTL (quantitative trait locus) mapping:

  • what it is
  • steps (3)
A

uses genetic markers to infer numbers and locations of genes affecting a quantitative trait

steps:
> identify molecular markers in a genome
> assign them to chromosomes (linkage groups)
> make crosses to identify associations between quantitative traits of interest

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

QTL (quantitative trait locus) mapping:

  • what conclusions to make from crosses
  • few loci controlling a trait
A
  • if differences in trait with difference in only one marker: locus of the marker must be linked with the trait
  • if there are differences in phenotypic trait and the individuals differ at one or more markers (in the combination fo their alleles),
    • then the phenotypic difference must be due to the genes at the markers
  • if few loci control a trait, then each one has a large effect on the trait -> few loci will explain lots of variance
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

genetic variance

environmental variance

A

genetic variance:

  • additive: contributions of each individual gene sum up
  • non-additive: gene contributions interact

environmental variance:
- effects of environmental variation

=> together determine variation in a phenotypic trait

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

variable heritability due to environment

A

same trait can show different heritability in a variable environment than in a uniform environment

(because in uniform environment, geentics become more of a source for variation)

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

correlated responses to selection

+ 2 kinds

A

when selection acting on one trait changes another trait, too

  • linkage disequilibrium
  • pleiotropy
  • e.g. butterfly eyespots selection only works if both selected for same colour
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

phenotypic plasticity

reaction norm

A

phenotypic plasticity: when genotypes produce different phenotypes in different environments

reaction norm: the set of phenotypes that a genotype can produce

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

measuring phenotypic plasticity

A

> place individuals with same genotype in different environments
traits varying between the environments are phenotypically plastic

  • amounts of variation are specific to the particular trait and envronment
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

barriers to interfertility (3)

A

1) premating
- ecological isolation
- mate selection differences

2) prezygotic/postmating
- mechanical isolation
- gametic isolation

3) postzygotic barriers
- extrinsic (hybrids poorly adapted or inable to find mates)
- intrinsic (hybrids low viability or sterile)

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

possible consequences of hybridization (5)

A

if hybrids less fit than parents:

  • none
  • reinforcement

if hybrids more fit than parents:

  • introgression
  • hybrid persistence
  • hybrid speciation
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

speciation without gene flow (2) and with gene flow (2)

A

without gene flow:

  • allopatric speciation (no geographical overlap)
  • peripatric speciation (founder effect)

with gene flow:

  • parapatric speciation (contact area, adjacent)
  • sympatric speciation (within same geographical range)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
allopatric speciation (2)
- most common | - due to geographical division
26
parapatric speciation (1)
emerges with environmental variation, | which creates reproductive barrier by changing fitness of specific genotypes
27
``` sympatric speciation (1) + problem ```
- some other-than-geographic barrier is established within the population - problem: if multiple loci are involved, then allele combinations that maintain that barrier should be recombined and lost
28
polyploid speciation + 1 example
- when hybrids get different chromosome count than parents, which establishes a reproductive barrier - salsify flowers: introduced to America in 1850s; polyploid hybrids became dominant species within 100 years
29
genetical bases of reproductive barriers (3 types)
- single-gene differences (e.g. moths, 1 gene, pheromone) - polygenic differences (e.g. monkeyflower shape > 30 genes) - chromosome differences - - different order and location of the same genes on chromosomes (e.g. dimsonweed species)
30
hybridization consequences: reinforcement
- increase in strength of pre-mating reproductive barriers | - > selection against hybridization, starts if post-mating barriers already exist
31
hybridization consequences: introgression
backcrossing of hybrids to one or both parent species, introducing genes of one side to the other
32
hybridization consequences: hybrid persistence
hybrids establish intermediate population in a hybrid zone
33
causes of speciation (5)
1) vicariance (spatial separation) 2) ecological divergence (occupying different ecological niches) 3) sexual selection 4) polyploidy/chromosomal rearrangement 5) hybridization
34
speciation: example for ecological divergence (1) and sexual selection (1) as cause
ecological divergence: benthic and limnetic sticklebacks sexual selection: higher speciation rate in promiscuous than pair-bonding birds
35
Muller's ratchet
in asexual populations, deleterious mutation accumulate with time -> no way to reduce number of mutations -> in sexual populations, recombination can reduce number of deleterious mutations
36
two-fold cost of sex | + problem
asexual species are expected to proliferate twice as fast as sexual species problem: > only applies to species with males and females > does not apply to hermaphrodites
37
advantages of sexual reproduction | short-term 4, long-term 1
short-term: - successful offspring in variable environment - combining of advantageous mutations into same genotype much faster in sexual populations - avoiding sib competition - avoiding Muller's ratchet long-term: - greater potential for populations to adapt to changing environments
38
disadvantages of sexual reproduction (3)
- meiosis is complex, more error-prone - necessity of combining gametes (and finding mates) - recombination might break favourable gene combinations
39
what defines gender?
gamete type: - male: many small gametes, mobile - female: few large gametes, last long
40
sex types (2)
- dioecious = individuals are either male or female | - hermaphrodite = individuals are both male and female
41
hermaphrodite types (3)
- simultaneous: male and female reproductive structures present at same time - sequential: - - protandrous: first male, then female - - protogynous: first female, then male
42
meiosis forms new genotypes by (2)
1) independent assortment of alleles | 2) crossing-over / recombination
43
asexual eukaryotes (3)
- entirely asexual eukaryotes rare - many eukaryotes can reproduce both sexually and asexually - asexual races are typically much younger than sexual races
44
age and reproductive fitness: - sooner offspring - those reproducing sooner...
offspring produced sooner: - more population growth because more generations in same time those reproducing sooner are: - smaller at maturity - have fewer offspring overall
45
semelparous species + formula + what yields more fitness + advantages to late reproduction (2)
- reproduce once per life - R = L x M - earlier reproduction typically yields higher fitness - advantages to late reproduction - - more offspring (e.g. larger plants) - - predator avoidance (e.g. cicada)
46
iteroparous species + formula + favoured if...
- reproduce multiple times per life - R = sum of (lx x mx) - favoured if offspring success for any given reproductive timeframe is unpredictable
47
reasons for tradeoffs on reproductive street (3 constraints)
1) genetic contraints - same allele may simultaneously confer both advantages and disadvantages 2) physiological constraints - ressorces allocated to one function cannot be allocated to another 3) phylogenetic constraints - organisms organisms are restricted by the abilities inherited from their ancestors
48
common reproduction tradeoffs (5, just look at these)
1. growth vs reproduction 2. reproduction vs survivorship 3. time to maturity vs number of offspring 4. nr. of offspring in one reproductive episode vs another 5. nr. of offspring vs cost of offspring
49
2 hypotheses on determinants of lifespan
1. individual organisms accumulate deleterious mutations acting late in life / after reproduction 2. selection favours alleles that confer benefits early in life / before reproduction, even if they're deleterious later
50
why females often live till long after reproduction (2)
- help with parental care | - may have knowledge and experience helping survivorship of their offspring
51
cooperation altruism
cooperation: benefits to both helper and recipient altruism: benefit to recipient, cost to helper
52
reciprocity conditions (4)
1. individuals can recognize each other 2. stable social groups (repeated interactions) 3. no strong dominance hierarchies 4. cost do donor must be less than benefit to recipient
53
group selection: Wynne-Edwards Williams recent model
Wynne-Edwards: altruistic groups reproduce faster than selfish groups Williams: within-population selection for selfishness is faster than between-group selection for altruism recent model: > groups are temporary > come together preiodically to form common gene pool > cooperative groups contribute more to common gene pool
54
true altruism can only evolve through...
group selection | cooperation can evolve by many mechanisms
55
kin selection: Hamilton's rule
altruism is favoured if: rxB > C (cost to donor is smaller than benefit to recipient, moderated by relatedness) -> predicts help directed toward more closely related individuals
56
genetic conflict between genomes: 2 types
1. conflict between organelle and nuclear genomes (e. g. thyme plant reverser alleles) 2. conflict between sex chromosomes and autsome (e. g. drosophila X killing Y and reverser alleles)
57
parental investment as an ESS (3)
- parents invest resources in rearing offspring - each parent is favoured to invest less when the other parent invests more, until an equilibrium is reached - where effort lines intersect is the equilibrium
58
sex allocation theory: when dioecity and hermaphroditism are favoured
dioecity favoured if: fitness is highest with specialization as either male or female hermaphroditism favoured if: fitness is highest with some allocation to male and some allocation to female function
59
hermaphroditism: self-fertilization (2) vs outcrossing (1)
self-fertilization: - greater reproductive assurance - contribute more of own genes to next generation outcrossing: - greater genetic variability in offspring (advantageous in unpredictable environments)
60
sex ratios: - average male and female fitness - how 1:1 is selected
- becaue every individual has one male and one female parent, average male fitness = average female fitness - 1:1 sex ratio due to negative frequency-dependent selection (less abundant sex has advantage) - in large population with reandom mating, leads to highest individual fitness if one's offspring has 1:1 sex ratio
61
causes of biased sex ratios (apart from genetics): - eusociality - local mate competition - environmental sex determination
eusociality: - queen decides whether to fertilize eggs (workers) or not (males) local mate competition: - female-biased sex ratios if mating in small groups of related individuals - female then produce just enough males to mate all females environmental sex determination: - physical or biotic enviromental cues
62
temperature-dependent sex determination (TSD) | + types (3 in total)
incubation temperature of eggs determines sex type I: single temperature threshold - - IA: low male, high female (turles) - - IB: low female, high male (crocs) type II: two temperature thresholds (turtles) - intermediate male - extremes female
63
sexual selection - fundamental identifying feature - what it leads to typically - when it arises
- fundamental identifying feature: variation in reproductive success is greater for one sex than for the other - typically leads to selection dimorphism - arises when one sex invests more resources per offspring than the other
64
mechanisms of sexual selection (4, just look at these yo)
- same-sex competition - - (to find mates; scramble competition) - - (to displace competitors; contests) - mate choice by opposite sex - sperm competition and mate guarding - coercion and infanticide
65
mate choice: what to choose by (3)
- direct benefits (food or resources) - indirect benefits (good genes) - pre-existing sensory bias (may lead to runaway-selection)

Evolution 355 (3 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions