Exam One Prep Flashcards
(112 cards)
1
Q
What is the difference between homologous and analogous structures?
A
Ancestry, homologous structures are structures that are shared from a shared ancestor whereas analogous structures are similar structures with no common ancestor.
2
Q
microevolution
A
allele frequency changes within species over relatively short time
3
Q
speciation
A
species lineages split to form new species
4
Q
macroevolution
A
large evolutionary changes above species level, taking place over much longer periods of times
5
Q
what are the 6 evidences for evolution
A
- fossils
- homology
- biogeography
- direct observation
- selective breeding
- vestigal traits
6
Q
creationism
A
the belief that the universe and living organisms originate from specific acts of divine creation, as in the biblical account, rather than by natural processes such as evolution
7
Q
fossil
A
any trace of an organism that lived in the past
8
Q
transitional fossils
A
fossils that show intermediate states between and ancestral trait and that of their descendants
an example with would be an archaepteryx, demonstrating modern feathers and a dinosaur like skeleton
9
Q
homology
A
similarity resulting from inheritance of traits from a common ancestor
10
Q
homologous structure
A
traits derived from a common ancestor
forelimbs of horses, dolphins and humans
11
Q
analogous structure
A
organisms with similar traits but evolved independently
spikes in porcupines and spikes in a pine tree
12
Q
developmental homology
A
embryos from different vertebrates showing similarities
13
Q
molecular homology
A
the nucleotide triplets (codons), universal genetic code demonstrating all life forms are related through common ancestry
14
Q
biogeography
A
geographic distribution of species on Earth
organisms that live in the same regions are often related
examples would be the hawaiian honeycreepers and marsupials
15
Q
direct observation examples
A
evolution of antibiotic resistant bacteria, insectiside resistance, industrial melanism ( peppered moth), covid-19
16
Q
selective breeding
A
also known as artificial selection
selecting mating partners by looking for various traits
domestication of corn
17
Q
vestigial traits
A
structured that derived from ancestor, no longer in use but present in reduced form
human tailbone, human arrector pili (goosebumps)
18
Q
malthusian dilemma
A
population when unchecked, increases exponentially and resources are outnumbered
19
Q
darwin’s interpretation of malthusian dilemma
A
species tend to produce more offspring than the enviornment can support, causing competition for those resources
20
Q
theory of catastrophism
A
earth was 6000 years oldd, living organisms on the planet were created after the great flood
21
Q
doctrine of uniformitarianism
A
geological processes that are going on today worked similarly in the past
(understanding history by examining this process and working backwards ?)
22
Q
Lamarck’s theory
A
transmutation of species and inheritance of aquired characteristics
23
Q
transmutation of species
A
organisms driven to greater complexity
adapting to enviornment and more complex to transform into another species
23
Q
inheritiance of aquired characteristics
A
change through use and disuse- characteristics of an organism develop during its lifetime in a response to enviornment and then passed down to offspring
common example is a giraffe stretching its neck to make it longer and passing that trait of a longer neck down to its offspring
24
darwin's theory
natural selection- those with any change variation that provides advantage will tend to be preserved
25
darwin's four postulates
1. principle of variation
2. principle of heredity
3. more offspring are produced than can survive
4. survival and reproduction are not random
26
epigenetics
heritiable changes that do not change DNA sequences
## Footnote
ex: stressed male rodents were able to pass on signs of traumas through their sperm RNA
27
principle of variation
within a population there is a variety of traits
28
principle of heredity
offspring tend to inherit their parents' characteristics
29
genotype
genetic makeup of a morphological trait
## Footnote
ex: BB, Bb, and bb
30
phenotype
an observed trait, expression of a genotype
## Footnote
ex: flower color
31
alleles
variant form of the same gene that share the same locus on chromosome
## Footnote
ex: B and b
32
Four Forces of Evolution
1. mutation
2. genetic drift
3. gene flow (migration)
4. natural selection
| changes allele frequencies in a population
33
population
a group of individuals of the same species that have a higher change to mate among themselves than individuals from another group
34
point mutations
a single DNA nucelotide that is inserted, deleted, or changed
| create new alleles at a genetic locus
## Footnote
ex: sickle cell anemia, color blindness, monarch butterfly resistance to milkweed
35
effects of point mutations on protein function
1. synonymous mutations
2. nonsynonymous mutations (missense or nonsense)
## Footnote
mutations caused by changes in DNA sequence
36
synonymous mutation
changes in DNA sequence that do not change the amino acid sequence
| also known as silent mutation
## Footnote
probably neutral with regard to natural selection
37
nonsynonymous mutation
changes in DNA sequence that change the amino acid sequence of a protein
## Footnote
two kinds: nonsense and missense
38
nonsense mutation
a codon is changed to a stop codon
39
missense mutation
codon is changed for a codon that codes for a different amino acid
40
chromosome inversion
segment of chromosome is inverted
| may not change the genetic information, but the order of genes changed
## Footnote
types: paracentric and pericentric
41
paracentric inversion
inversion that doesn't include centromere
42
pericentric inversion
inversion includes centromere
| easily identifiable through karyotyping
43
what does chromosome inversion often cause?
## Footnote
A. significant gain in DNA.
B. significant loss in DNA.
C. creation of nonfunctional pseudogenes.
D. suppression of recombination.
D. supression of recombination
| reduces crossing over within inverted regions and increases it in others
44
inversion heterozygote
one set of chromosomes with normal gene sequence, the other set has inverted gene sequence
## Footnote
rarely produces recombinant gametes
45
gene duplication
a region of DNA is duplicated
46
mechanisms of gene duplication
1. unequal crossing over during meiosis
2. retrostransposition
3. whole-genome duplication
47
unequal crossing over during meiosis
homologous chromosomes misaligned at the prophase stage of meiosis l
## Footnote
results in gene duplication in one chromosome and deletion in the other
48
retrotransposition
instead of being translated into proteins they are reverse transcribed into DNA sequence
## Footnote
ex: chondrodysplasia in dogs
49
retrotransposons
mobile genetic elements that can cause insertion mutations and gene duplication
| also known as jumping genes
50
whole genone duplication
entire set of chromosomes is duplicated
51
nondisjunction
homologous chromosomes or sister chromatids fail to separate during cell division
52
polyploidization
nondisjustion causes this: common in plants that self fertilize, prevents offspring from interbreeding with parent species
| different # of chromosomes comapred to parent species (typically double)
## Footnote
common source of speciation in plants
53
# Which of the following statements is not true?
A. Duplicate genes usually take on new functions.
B. Chromosome inversion does not cause gene duplication.
C. Whole-genome duplication may cause speciation.
D. Human globin gene family is an example of gene duplication.
A. Duplicate genes usually take on new functions.
54
genetic variation
genetic differences found in indivudals or populations
## Footnote
measured genetic variation by polymorphism and heterozygosity
55
polymorphism (P)
estimate of loci that are polymorphic
| high polymorphism = high genetic variabillity
## Footnote
polymorphic locus: the most common allele is no more than 95%
56
heterozygosity (H)
% or fraction of loci that are heterozygous
| can be applied to individual or population
## Footnote
high heterozygosity = high genetic variation
57
genetic load
natural selection is very ineffective at removing rare recessive deleterious alleles from a population
| in short- unfavorable alleles
58
sex-linked traits
generally is a trait that occurs on the X chromosome
| genotype frequency of x-linked traits in males = allele frequency
## Footnote
h-w is then applied differently for these traits
59
what does hardy-weinberg equilibrium demonstrate?
| what is its use?
evolution won't occur in a population if its five conditions are met
| provides an estimate of expected allele frequency assuming no evolution
60
hardy-weinberg equations
p+q=1
p^2+2pq+q^2=1
## Footnote
p^2 is frequency of homozygous dominant
2pq is frequency of heterozygous
q^2 is frequency of homozygous recessive
61
# If population meet all HWE assumptions which of the statements is true?
A. The population will evolve way more slowly than normal.
B. The population does not evolve as long as these conditions
hold.
C. Dominant alleles in the population's gene pool will slowly
increase in frequency while recessive alleles will decrease.
D. The population has an equal frequency of dominant and
recessive alleles.
B. The population does not evolve as long as these conditions
hold.
62
Five conditions for HWE
1. No mutation
2. No genetic drift (i.e. infinitely large population)
3. Random mating
4. No migration (no gene flow)
5. No selection
## Footnote
these are essentially the driving forces of evolution MINUS RANDOM MATING
63
Why is nonrandom mating not a source of evolution?
Nonrandom mating changes genotype frequency, but there is no change to allele frequency
64
natural selection
surrival and reproductive success due to differences in phenotype
| occurs as a result of individual differences in fitness
## Footnote
causes adaptation
65
adaptation
how individuals better fitted to surrvive in their enviroment
| three main kinds: structural, physiological and behavioral
66
fitness
avg # of offspring of a individual with a certain genotype compared to that of another
| usually abreviated as
## Footnote
a measure of the contribution of a genotype to the gene pool of the next generation
darwin described this as the abillity to survive, find mate and reproduce
67
general selection model (GSM)
predicts changes in allele freq. from one gen to the next due to natural selection
68
w=1
genotype with highest fitness and highest reproductive success
| w<1 (fitness of other genotypes will be less than 1)
69
selection coeffcient (S)
measure of the relative strength of selection acting against a genotype
## Footnote
can be thought of as the reduction in fitness
70
fitness and selection coefficient equation
s+w=1 or s=1-w
71
5 general models of natural selection
1. selection against recessive allele
2. selection against dominant allele
3. heterozygote had intermediate fitness
4. heterozygous advantage
5. selection against heterozygote
72
# general model #1:
selection against recessive allele
| what happens to the alleles?
AA: 1
Aa:1
aa: 1-s
## Footnote
Allele A will be the most common but will not be fixed and by the only one
frequency of allele a will be low but it will not reach 0
73
# General Model #2
Selection against dominant allele
AA: 1-s
Aa:1-s
aa: 1
## Footnote
allele a will be fixed at this locus
allele A will be removed from the population
74
# General Model #3: directional
Heterozygote has Intermediate Fitness
AA: 1-s
Aa:1-s/2
aa: 1
(selection for allele a & removes allele A from pop. )
OR
AA: 1
Aa:1-s/2
aa: 1-s
(selection for allele A & removes allele a from pop.)
| changes in p and q will be slower
## Footnote
allele that is favored by selection will be fixed, allele A will be fixed
75
# General Model #4:
Heterozygote Advantage
AA: 1-s
Aa:1
aa: 1- t
| t is selection coefficient like s
## Footnote
there are several names for this, heterosis, overdominance
leads to stable polymorphism BOTH alleles remain in population
76
# Model of Selection #5
Selection Against Heterozygote
(“Underdominance”)
AA: 1-
Aa:1-s
aa: 1- s
| leads to disruptive selection, **equilibirum is UNSTABLE**
## Footnote
whichever allele is at highest frequency will likely become fixed
polymorphism is NOT maintained
77
Frequency dependent selection
the fitness of a genotype of allele is affected by its frequency in the population
78
postive frequency dependent selection
allele or genotype enjoys higher fitness when it is common
## Footnote
a rare allele will be at a selective disadvantage and CANNOT maintain polymorphism
79
negative frequency dependent selection
allele or genotype enjoys higher fitness when it is rare
## Footnote
a rare allele will have an advantage leading to stable polymorphism
ex: scale eating fish, right and left handed fish
80
gene flow (migration)
movement of alleles among populations (movement of individuals)
## Footnote
**homogenizes genetic differences and keeps popualtions similar to each other **
81
what are the factors that affect gene flow?
1. vagility
2. distance
3. barrier
82
vagility
the abillity to move
## Footnote
higher vagility higher gene flow
83
distance
between different populations
## Footnote
greater distance, lower gene flow
84
barrier
geographical isolation that prevents movements of individuals
## Footnote
stronger barrier, lower gene flow
85
outbreeding depression
cross between genetically distinct groups may produce offspring with lower fitness
## Footnote
ex: apline ibex capra ibex- hybrids between the two birthed calves too early causing the entire population to disappear
86
relationship between gene flow and genetic drift?
gene flow and genetic drift have **opposite** effects
87
extinction vortex
small populations become increasingly vunerable toward extinction
88
genetic drift
random change of allele frequencies over generations due to change or "sampling error"
## Footnote
results in LOSS of genetic variation, effects are strongest in small populations
89
types of genetic drift
bottleneck and founder effect
90
bottleneck effect
caused by catastrophic effect that greatly reduces population size
## Footnote
ex: australia bushfires 2019-2020
whooping cranes- hunted nearly to extinction, from 6 mitochondrial types, there are now only 1
91
founder effect
caused by ecological seperation through migration from orginal population
| in simpler terms, small group break off and make new population
## Footnote
allele frequencies of new population will differ than that of the source pop.
92
effective population size (Ne)
effect of genetic drift is determined by this
## Footnote
influenced by the mating system (breeding ratio)
93
polygyny
males mate with multiple females
94
polyandry
females mate with multiple males
95
effective population size equation
Ne = (4 * Nm * Nf) / (Nm + Nf)
| Nm = number of breeding males
Nf= number of breeding females
96
factors influencing Ne
* influenced by the mating system (breeding ratio)
* fluctuation census population size over time (bottlenecks lower Ne)
* variation in family sizes ( if some families have many more offspring, lower Ne)
* sex ratio (unequak sex ratio lowers Ne)
97
types of nonrandom mating
1. negative assortive mating
2. positive assortive mating
98
negative assortive mating
mates between DIFFERENT phenotpes
## Footnote
progressive incr. in the # of HETEROzygotes
99
positive assortive mating
mates between similar phenotypes
## Footnote
progressive incr. in the # of HOMOzygotes
100
inbreeding
mating among close relatives, increases homozygosity at all loci
## Footnote
(type of positive assortive mating)
101
self-pollination in plants
extreme forms of positive assortive mating and inbreeding
102
what happens to allele frequencies in nonrandom mating
**NOTHING**
## Footnote
p and q remain the same
103
inbreeding depression
reduced fitness due to inbreeding
## Footnote
increased homozygosity, expression of deleterious recessive alleles
ex: greater prarie chicken in illinois
florida panther
104
genetic load
collection of deleterious recessive alleles
105
genetic rescue
augment gene flow into small populations to reduce inbreeding depression
## Footnote
successful cases- greater prarie chicken, florida panther
unsucccessful- outbreeding depression in alpine ibex
106
quantitative genetics
looks at the evolution of multilocus traits that show continuous variation
107
quantitative traits
product of both genotype and enviornment
| has continuous variation, typically are controlled by multiple genes
## Footnote
ex: morphology (size and shape)
physiology ( pressure, temperature)
performance ( speed, puzzle solving)
fitness ( seeds, suriviving offsrping)
108
multilocus trait
combination of alleles found at two or more loci in a single individual
109
hertiable variation- individual level phenotype equation
Phenotype(P) = genotypic effects (G) + enviornmental effects (E)
## Footnote
for the single locus traits enviornmental effects E= 0
110
Phenotype equation (other ver. )
Vp= Vg + Ve
## Footnote
Vp = phenotypic variance
Vg = genetic variance
Ve = environmental variance.
111
heritabillity (h^2)
proportion of the variance in phenotype that is transmissible from parents to offspring
## Footnote
influenced by genetic, ranges between 0 and 1, one being that the only influence is genetics
can be used to predict changes in the population as a result of natural selection
