Chapter 13: How Populations Evolve Flashcards
1
Q
Aristotle believed…
A
life is fixed
2
Q
describe Lamarkian Inheritance
A
- inheritance of acquired characteristics
- lineages don’t go extinct
3
Q
What helped shape the theory of evolution and natural selection?
A
worldwide voyages
4
Q
list some observations from travels?
A
- organisms within geographic proximity are more similar
- the planet is changing
- fossils resemble individuals extinct to a region
5
Q
Darwin called his theory
A
descent with modification
6
Q
decent with modifications explains
A
- all life is connected by a common ancestor
- descendants have accumulated adaptations
7
Q
define a theory…
A
a widely accepted explanatory idea
8
Q
fossil record provides evidence for
A
evolution
9
Q
3 characteristics of fossils
A
- imprints of past organisms
- document differences between past and present organisms
- reveals that many species are extinct
10
Q
in the late 1970s paleontologists thought whales arose from
A
a wolf-like carnivore
11
Q
define homology
A
similarity due to shared ancestry between a pair of structures or genes
12
Q
what reveals evolutionary relationships?
A
structural and molecular homologies
13
Q
DNA also shares
A
evolutionary history
14
Q
define vestigial structures
A
remnants of features that serve important functions in the organisms ancestor
15
Q
define evolutionary tree
A
branch diagram showing the evolutionary relationship among organisms
16
Q
define the nodes of an evolutionary tree
A
represents the common ancestor
17
Q
define the hatch of an evolutionary tree
A
the shared homologous structure
18
Q
define a clade of an evolutionary tree.
A
all organisms that share a common ancestor
19
Q
Darwin proposed what as the mechanism of evolution?
A
natural selection
20
Q
What was Darwin’s greatest contribution to biology?
A
his explanation of how life evolves
21
Q
artificial selection shows insights into…
A
how incremental change occurs
22
Q
Difference between artificial selection and natural selection?
A
artificial selection can bring change in a short period of time
natural selection modifies species over thousands of generations
23
Q
What is heritable?
A
natural variation in a population
24
Q
overtime favorable traits…
A
accumulate in a population
25
list the 3 key points to natural selection
1. the population, not the individual, evolves
2. natural selection ONLY acts on heritable traits
3. evolution is not goal directed
26
evolution is AKA
change in allele frequencies
27
What is an example of natural selection in action?
- the evolution of pesticide resistance in hundreds of insect species
- human resistance to antibiotics
28
give 2 examples of how natural selection can be observed in natural populations
1. Galapagos finches and drought
| 2. black snakes and invasive toads
29
evolutionary adaptation relies on the...
available genetic material
30
examples of available genetic material include?
- changes in allele frequencies through time
| - varying population that fits the current and local environment
31
What produces the genetic variation that makes evolution possible?
mutation and sexual reproduction
32
Organisms typically show...
individual variation
33
Define mutations...
the ultimate source of genetic variation that serves as raw material for evolution
an alteration or change in DNA sequence
34
In organisms that reproduce sexually, where does most of the genetic variation in that population come from?
the unique recombination of alleles inherited by each individual
35
define a gene
a sequence of nucleotides in DNA or RNA that encodes the synthesis of a gene product
36
define an allele
alternate from of a gene
37
many alleles form a gene and many genes form a
trait
38
mutation characteristics...
- can provide novel or improved gene function
| - most often deleterious and quickly removed from a population
39
what is an example of a mutation?
garter snakes become resistant to the poison of frogs, but it cost them the agility of being able to move quickly
40
3 ways that sexual reproduction contributes to genetic variation
1. crossing over
2. independent assortment of alleles (in metaphase 1)
3. random fertilization
41
define synapsis
pairing up of homologous chromosomes in meiotic prophase
42
What occurs during synapsis?
- each pair of homologous chromosomes form a bivalent
| - bivalents condense an form a tetrad
43
chiasma forms during
prophase I
44
define crossing over
nonsister chromatids exchange genetic material
45
define terminalization
centromeres attach to spindles and nuclear envelope breaks down
46
what holds the nonsister chromatids together?
terminal chiasmata
47
during anaphase I
- homologous chromosomes separate
| - nondisjunction may occur
48
characteristic of telophase I
reappearance of nuclear membrane and short interphase
49
when does crossing over occur?
during meiotic prophase
50
What results in a great amount of genetic variability?
crossing over
51
formula for the number of unique gametes
2^(# of paired chromosomes)
52
define a population
a group of individuals that live in the same area and interbreed
53
define a gene pool
all copies of every type of allele, at every locus, in all members of the population
54
define microevolution
a change in frequencies of alleles in a population's gene pool and evolution occurring at a small scale
55
what are Mendel's postulates?
- genes exist in pairs
- dominant/ recessive alleles
- unit factors segregate independently
- independent assortment
56
what does the Hardy-Weinberg equilibrium state that alleles and genotype frequencies will remain constant if...
- a population is infinitely large (no genetic drift can occur)
- mating is random
- no mutations
- no gene flow
- no natural selection
57
What shows if a population is evolving?
changes in allele frequencies
58
define gene flow
transfer of genetic material from one population to another
new alleles at different frequencies
59
what equation holds true when a population is not evolving?
p^2+2pq+q^2=1
60
How do public health scientists use the Hardy-Weinberg equilibrium?
to estimate how many ppl are carry alleles for certain inherited diseases
61
mechanisms of microevolution
- genetic drift
- selection
- gene flow
62
define genetic drift
changes in allele frequencies from chance alone (in small pop.)
63
define selection
changes in allele frequency from differential reproduction
64
genetic drift is often caused by
- bottleneck effect
| - founders affect
65
define bottleneck effect
loss of genetic diversity when a population is greatly reduced
66
define founder's effect
when a few individuals colonize an island or other new habitat
67
the bottleneck effect and founder effect are more pronounced in
SMALL populations
68
What is often a major consideration in endangered species?
inbreeding depression
69
define inbreeding depression
negative effect of homozygosity on a population
70
what is the ONLY evolutionary force that consistently leads to adaptive change in a population?
natural selection
71
what increases as a result of natural selection?
favorable traits
72
define relative fitness
contribution one makes to the gene pool of the next generation, relative to the contributions of other individuals
73
What are the 3 different types of selection?
1. directional
2. stabilizing
3. disruptive
74
describe directional selection
one spectrum of a phenotype has higher fitness than the other
75
describe stabilizing selection
lower fitness of extreme phenotypes
76
describe diversifying selection
extreme phenotypes are more extreme than intermediate ones
77
define sexual selection
a form of natural selection in which individuals with certain characteristics are more likely to secure a mate
78
what are the 3 types of sexual selection?
1. INTRAsexual selection
2. INTERsexual selection
3. honest vs. dishonest signaling
79
define intrasexual selection
occurs when individuals compete directly with members of the same sex for mates
80
intersexual selection
selection in mate choice
-females being choosy in selecting their mates
81
How do we contribute to the problem of antibiotic resistance?
- doctors overprescribing antibiotics
- patients prematurely stop taking antibiotics
- livestock producers add antibiotics to animal feed
82
How does diploidy preserve variation?
by "hiding" recessive alleles through balancing selection and heterozygous advantage
83
when does balancing selection occur?
when natural selection maintains stable frequencies of two or more phenotypic forms in a population
84
Give an example of balancing selection
side blotched lizards
85
define heterozygote advantage
heterozygous individuals have a greater reproductive success than either type of homozygote. Results that 2 or more alleles for a gene are maintained in the population
86
examples of heterozygote advantage
sickle cell gene and malaria
