Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

evolution > envs lecture 6 (first 16 slides) > Flashcards

envs lecture 6 (first 16 slides) Flashcards

1
Q

what changed human civilization

A

selective breeding/domestication for agriculture

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

when did humans harness evolution

A

11,000 years ago

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

examples of selective breeding

A

bred wheat that provided more grain, cows that produced more milk

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

what did this selective breeding/domestication do

A

allowed ppl to abandon nomadic lifestyle and settle in communities

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

quantitative traits

A

traits that vary continuously and are therefore affected by anywhere from several to thousands of loci

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

example of quantitative traits

A

crop yield, milk production, body height

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

what are polygenic traits

A

quantitative traits; vary continuously, affected by several/thousands of loci [poly genic cuz multiple genes]

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

quantitative genetics

A

study of how quantitative traits are inherited and how they evolve

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

what effects quantitative traits

A

both genes and environment interact to affect it

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

example of domesticated plant

A

modern corn

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

where do phenotypic differences in branching pattern between modern corn and its ancestor come from

A

small number of genetic changes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

examples of other differences

A

size of cob

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

where do differences in size of cob come from

A

changes at many loci

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

example of quantitative trait that varies continuously

A

human height

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

what is a normal distribution (varies continuously) curve look like

A

bell-shaped curve

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

genotypic variatoin

A

encoded in DNA: only 4 possible nucleotides, A, T, C, G

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

is genotypic variation discrete or continuous

A

discrete

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

is phenotypic variation discrete or continuous

A

continuous

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

what is another word for phenotypic traits

A

quantitative traits

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

what kinda distribution for quantitative/phenotypic traits

A

normal distribution

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

what kinda curve for quantitative traits

A

bell shaped curve

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

how do traits go from discrete genotype to continuous phenotype

A

many traits affected by many genes AND environmental influences on individual within its lifetime

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

are quantitative traits affected by many or only a few genes

A

many genes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

example of quantitative traits

A

height

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
how many genes is height influenced by
thousands
26
how else are phenotypic traits influenced
by the environment over lifetime of individual
27
is this environmental influence genetic or non genetic
non-genetic
28
what does this variance in environment do to bell curve
smooths it out
29
can we see genotypes
no
30
is phenotype or genotype directly seen
phenotype
31
what is discrete vs continuous phenotype determined by
combo of genetic and environmental variation
32
what are blue bars
frequencies of phenotypes in population w/o influence of environmental variance
33
green curves
frequencies of phenotypes for each of genotypes in given population w/ addition of environmental variance
34
red curves
frequencies of phenotypes for entire population
35
what does selection act on
phenotype; at level of individual
36
how do phenotypic distributions become w/ more loci
smoother
37
what happens w/ more loci
phenotypic distributions become normal
38
what else can smooth out phenotypic distribution
more environmental variance
39
what can occur from evolution of allele frequencies w/o addition of new mutations
large changes
40
important component of evolution of quantitative traits
large changes in quantitative traits can occur by evolution of allele frequencies w/o addition of new mutations
41
what is a key point for this polygenic quantitative trait
phenotypic distributions for allele frequencies p = 0.25 and p = 0.75 do not even overlap
42
what can happen w/ multiple loci
can move outside initial range
43
what do horns on head of horned lizard do
deters predation
44
where is the natural variation in lizards
variation in length of these protective horns on head of lizard
45
what does survival vary with for lizards
length of horn
46
what does fitness function show
lizards w/ longer horns survive better
47
what do fitness functions show
describe/quantifies how selection acts on quantitative traits
48
3 basic modes of selection on quantitative traits
directional, stabilizing, disruptive
49
what does directional selection do
favors change in the mean of a trait in one direction (either toward a greater or lesser value)
50
what does stabilizing selection do
favors individuals near the population mean
51
what does stabilizing selection reduce
phenotypic variance in trait --> gives narrower population phenotypic distribution
52
what does disruptive do
favors largest and smallest
53
what does disruptive do to variance
increases variance in the trait
54
example of directional silection
drought led to changes in seed size; larger bills have higher survival ate --> mean beak size shifted and became larger
55
example of stabilizing selection
human birth weight; infants w/ birth weight much smaller and much larger than average have lower probability of survival
56
example of disruptive selection
black bellied seedcracker survival depends on lower mandible length; intermediate birds have lowest survival and become less common --> smallest and largest billed ones have highest fitness
57
what does the type of selection acting on an organism depend on
both phenotypic distribution of organism and phenotypic distribution of food items
58
when is directional selection at play
most individuals in a population fall within a region of the plot where the fitness function is increasing/decreasing [bill evolves toward a size that is optimal for feeding on hemlock]
59
when is stabilizing selection at play
if population lies near a peak of the fitness function [tightens the mean around the bill size optimal for feeding on seeds from lodgepole pine cones]
60
when is disruptive selection at play
if population lies at a low point in fitness function [causes bill size to evolve both larger and smaller towards the two diff sized but available food items]
61
can selection act on more than one phenotypic trait at once
yeah
62
correlational selection
selection favors combos of traits
63
what do evolutionary biologists ask
how and why mean values of traits evolve (often caused by directional selection); important to quantify the strength of selection
64
selection gradient
measures strength of directional selection on a quantitative trait
65
relative fitness
individual fitness/mean fitness all individualsh
66
how do you mesaure selection gradient
measure trait of interest and fitness for a set of individuals who vary in the trait of interest
67
positive beta
indicates selection favors larger values of the trait
68
negative beta
indicates selection favors smaller values of the trait
69
beta is zero means
no directoinal selection
70
female guppies
prefer males w/ more orange
71
who has higher fitness among male guppies
males w/ more orange
72
moderately strong directional selection
-0.5 and 0.5
73
very strong directional selection
1
74
is directional selection always strong
sometimes; other times it isn't
75
Stronger selection gradient (Beta produces
larger change in size
76
Lower, but positive gradient (Beta) produces
smaller change in mean trait value
77
negative selection gradient (-0.5 Beta)
produces a small reduction in size
78
positive beta selection for
larger size
79
negative beta selection for
smaller size

evolution (15 decks)

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