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Botany/Zoology > PP1-3 Test > Flashcards

PP1-3 Test Flashcards

1
Q

a proposed explanation for phenomena to guide investigations

A

hypothesis

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2
Q

repeatedly tested hypotheses used to explain and predict phenomena or accepted explanation for observations, backed by scientific evidences

A

theory

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3
Q

Worked in 1830’s to 1850’s
In 1859, wrote his ideas about evolution (which at that point was a hypothesis) in a book called
On the Origin of Species by Means of Natural Selection
(basically a journal of his observations & questions), he didn’t call his ideas “evolution

A

charles darwin

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4
Q

3 word phrase for what Darwin called his hypothesis as proposed in his book…

this means that genes are modified (or changed/varied) & some of these changes are passed to an organism’s descendants & if it allows them to be better suited for their environments it leads to adaptations

A

“descent with modification”

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5
Q

Darwin’s ideas of evolution are now a ____ because of the repeated evidences that support it

A

theory

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6
Q

States that…“Organisms change gradually over time as a result of adaptations”

As the organisms change, their variation allows for differential survival and reproduction because nature selects, or allows, for the individual organisms that are best suited to their environment to pass on their traits to their offspring leading to adaptations and evolution of the species

A

Gradualism AKA Darwinism

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7
Q

change between species over time, one species replaces another, old species go extinct when replaced (will learn this later such as dinosaurs replaced by mammals)

A

macroevolution

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8
Q

change within species over time, see next slide, microevolution leads to macroevolution

Change within a species’

A

microevolution

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9
Q

microevolution ex.

A 
Genetic variations occur for a variety of reasons
If genetic variations are heritable and beneficial, then individuals pass on their traits to their offspring, if some survive “better” than other others then.. 
Natural selection (over many generations) allows members of the species that survived to produce more offspring and keep passing on these “variations” to their offspring
Natural selection leads to an organism’s adaptations to their environment 
Evolution results
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10
Q

4 Principles of Darwin’s Theory of Evolution (by means of natural selection)

A

overpopulation, genetic variation, Struggle for existence/ Survival of the fittest, Natural selection

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11
Q

random variances or differences between individuals, the ‘why’ or ‘raw material’ for evolutionary change

A

genetic variation (heritable)

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12
Q

when individuals with heritable variations are better adapted they are chosen by nature to survive and reproduce, the ‘how’ or ‘mechanism’ for evolutionary change

A

natural selection

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13
Q

More babies born than can survive since so many things in environment can affect their mortality

A

overpopulation

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14
Q

Random differences or variations occur between individuals within the same species due to ________(exs. mutation or sexual reproduction and meiosis) but only heritable traits are passed onto offspring

A

genetics

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15
Q

Competition occurs between individuals such as predator with prey, male with male, or plant with plant. Competition occurs for living space, food, water, mates, etc. The organisms with the best heritable variations will survive due to being the most “fit” or best adapted to reproduce

A

Struggle for existence/ survival of the fittest

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16
Q

Natural selection allows those organisms with the most suitable heritable traits to survive and reproduce and pass those traits onto their offspring leading to adaptations BUT it does NOT produce perfection and does NOT have a goal and is NOT random, although variation is

A

Natural selection through differential survival and reproduction

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17
Q

Mutation, sexual reproduction, and genetic recombination during sexual reproduction lead to _______ ______

A

genetic variation

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18
Q

CAN lead to inheritance, if so then their can be a struggle for existence/survival of the fittest

A

genetic variation

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19
Q

Then _______ ________ occurs due to differential survival and reproduction which then leads to adaptations

A

natural selection

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20
Q

BUT if humans intervene then _______ _______ can have the same outcome

A

artificial selection

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21
Q

are “characteristics that result from natural selection when (heritable) traits are passed onto offspring resulting in organisms being better suited to their environment”

Often occur because of changes in organisms’ habitat

A

adaptations

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22
Q

Structural

way a structure looks

A

Anatomical (or morphological) adaptations

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23
Q

Functional

Helps a structure do something better

A

Physiological adaptations

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24
Q

If there is an anatomical adaptation, it is for a _______l reason

_______adaptations occur and result in anatomical changes as well

A

Physiological

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25
Q

Includes ‘instincts’ such as migration

A

behavioral adaptations

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26
Q

Adaptations lead to different types of _______

A

evolution

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27
Q

Unrelated organisms evolve similar adaptations but in different places due to similar habitats and niches

A

convergent evolution

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28
Q

Common ancestry leads to a diversity of species separating from a single point resulting in shared traits since all life originated from extinct ancestral species

A

divergent evolution

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29
Q

Divergence from a common ancestor, organisms separate due to isolation and adapt to changing habitats and niches

A

adaptive radiation and divergent evolution

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30
Q

Original species from which new species radiate

A

founder species

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31
Q

Formation of new species due to isolation of members from different populations resulting in not being able to interbreed, ONLY members of same species can interbreed

A

speciation

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32
Q

Isolation leads to _________(geographical, temporal, behavioral, mechanical etc)- populations of the same species living in different locations tend to evolve in different directions, as two populations become separated they become isolated so they can no longer interbreed and become different species (leading to new species being formed called speciation)

A

speciation

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33
Q

Natural selection causes change within ________- because traits of individuals allow the population to adapt to its environment due to genes, mutations and recombination of genes during sexual reproduction provide genetic variation upon which natural selection acts (microevolution)

A

populations

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34
Q

leads to species replacement- due to climatic changes and natural disasters some species become extinct and they are replaced by species that are better adapted (macroevolution)

A

extinction

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35
Q

his (Darwin) journey on the

(ship) as friend of the captain

A

HMS Beagle

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36
Q

raveled around the world and kept a journal of his questions
and observations, he was a naturalist, see next slide

A

Journey on the HMS Beagle

1831-1836

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37
Q

Plants and animals on these islands closely resembled those from the west coast of South America (where Darwin traveled)

A

Galapagos Islands

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38
Q

Darwin found many species that were _______ to certain areas only esp. Galapagos, but also found some species in one part of the world that were similar to species in other areas, also found extant species similar to fossils of extinct species???

A

endemic;

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39
Q

species native and unique to one area

A

endemic species (gal tort)

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40
Q

biblical idea, widely believed at time

A

Catastrophism

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41
Q

One of first to envision evolution

But did not believe in extinction

Believed the “need” of organisms drove evolutionary changes

A

Lamack

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42
Q

“ law of use and disuse”- if needed, use it and it evolves, if not used then doesn’t evolve

“inheritance of acquired characteristics”- he believed that if “need” drives evolution, then an organism will pass on traits acquired to offspring

Not accepted in scientific world

Darwin used same evidences for evolution as Lamarck did, but different arguments for it and not based upon “belief” but rather observable evidence

A

Lamackism

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43
Q

An Essay on the Principle of Population

Darwin read ______ and used the ideas for all organisms…. “overpopulation, competition among siblings, and genetic variation leading to slightly greater chance of survival”

A

Malthus

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44
Q

Principles of Geology
geologist who came up uniformitarianism - slow, gradual geological processes shape the earth
Darwin used the idea to explain fossil placement in rock and used to determine age of the fossils and when the organisms lived
In opposition to biblical idea of catastrophism
Oldest rocks on bottom, youngest on top since rocks laid down gradually

A

Lyell

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45
Q

Darwin used his observations and then read Lyell and learned about Lamarck, envisioned biological uniformitarianism similar to Lyell’s geological uniformitarianism; also believed that Malthus’ ideas pertained to all organisms, also influenced by Mendel’s ideas on genes too

“Evolution occurred over generations,
too slowly to be perceived”

A

effects on Darwin

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46
Q

Worked in South Pacific while Darwin was working in other parts of world
Corresponded with Darwin and shared his own theory of evolution with Darwin
Importance- Forced Darwin’s hand in publishing his book

In 1859, Darwin had to publish his book On the Origin of Species by Means of Natural Selection quickly so as to beat out Wallace, even though he wasn’t ready

Darwin’s book became a best seller eventually but it took the discovery of genetics to get the book to that point

Making similar observations as Darwin but in a different part of the world - Malaysia

A

Wallace

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47
Q

Not an influence on Darwin, rather Darwin was an influence on Gould - punctuated eq.

A

Gould

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48
Q

Species do not change for long periods then there are brief episodes of ‘fast’ speciation
Gould developed this idea because not all evolution and fossil records can be explained by gradualism
Ex. fossils from mass extinction events
Ex. Burgess Shale fossils showing
evolution during Cambrian explosion

A

Punctuated Equilibrium (P.E.)

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49
Q

Evidence for evolution supports _____ Darwin’s view and Gould’s view

A

both

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50
Q

due to meiosis during sexual reproduction

A

genetic shuffling or genetic recombination

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51
Q

cell division that involves reduction in chromosome number, from diploid to haploid so a parent only passes on ½ of his/her chromosomes to offspring

A

meiosis

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52
Q

During meiosis, homologous pairs of chromosomes line up & genes switch from 1 chromosome to another before fertilization occurs

A

crossing over

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53
Q

fusion of 2 haploid gametes (sperm, eggs) to make 1 diploid zygote, each offspring has ½ of his/her chromosomes from each parent so each offspring is from his/her siblings depending on which gametes form the zygot

A

fertilization

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54
Q

Gregor Mendel: 1857

Discovered how genes work by studying genetics in pea plants by cross pollination (pollen from one plant to another) for desired traits= artificial selection

Dominant  “T”
Recessive “t”
Genotype “TT” “Tt” “tt”
Homozygous “TT” “tt”
Heterozygous “Tt”
Phenotype- physical expression  ex tall, shortPunnett Square- given certain parental genotypes it provides representation of genotypes and phenotypes for offspring
A

Mendelian Genetics

55
Q

used to explain the concepts from previous slide #6 …..Mendel discovered that 2 “alleles for a gene separate into gametes when they are made during meiosis, each gamete receives ONLY 1 of the 2 alleles
Depending which alleles combine during fertilization, the phenotypes of the offspring are varied from the parents and from each other, so the phenotype output illustrates genetic shuffling/recombination

A

law of segregation

56
Q

As discovered by Mendel, when examining 2 traits/genes, “the alleles from the 2 or more different genes separate from one another and segregate independently of one another when gametes are made” and during fertilization, AGAIN illustrating genetic shuffling/recombination of the offspring

A

Law of independent assortment

57
Q

genetics means that these inheritance patterns are different from what Mendel found where 1 trait is dominant & 1 is recessive

A

Non-Mendelian

58
Q

more than 2 alleles for a trait, allows for more than 3 genotypes & 2 phenotypes of offspring (not just 1 dominant and 1 recessive)

A

Multiple alleles

59
Q

2 of the multiple alleles from slide #9 are equally dominant and both are equally expressed when they are together in a genotype

A

Non-Mendelian genetics

Codominance

60
Q

still 3 genotypes RR, Rr, and rr but
3 phenotypes- RR=dominant red, rr= recessive white, and Rr= intermediate (blended or mixed for heterozygous genotype) so pink

A

incomplete dominance

61
Q

alleles available for offspring in a gene pool can be different for different populations of a species in different locations around the world & can change with migration

A

alleles available in a population’s gene pool

62
Q

interbreeding members of a species

A

population

63
Q

all genes/alleles available in a population for a trait

A

gene pool

64
Q

alternative forms of a gene

A

alleles

65
Q

movement of individuals from one place to another, can change alleles available, due to gene flow between gene pools

A

migration

66
Q

% of an allele in a population

A

allele frequency

67
Q

Because of genes available in the gene pool, allele frequency can be different in different locations of the world and at different times,_____ can lead to gene flow between gene pools thus result in changes in allele frequency

A

migration

68
Q

jumping genes’
genes that can move from one area of a chromosome to another area of a chromosome, often within another gene, so that they inhibit the expression of those genes (interfere with the protein the gene codes for, thus changes the phenotype for that gene)

Barbara McClintock
discovered transposons in maize and won the Nobel Prize in Physiology or Medicine in 1983 for the discovery

A

transpsons

69
Q

makes up genes, genes are found on chromosomes,

and genes code for proteins (gene expression= the protein the gene codes for and the phenotype it causes

A

background DNA

70
Q

makes mRNA during transcription of protein synthesis, mRNA pairs with tRNA’s during translation of protein synthesis in order to assemble amino acids into a polypeptide and later a protein

A

background DNA

71
Q

in DNA COULD affect or change the mRNA or tRNA as well as amino acids they code for, thus could affect or change the protein produced, but sometimes it does NOT change anything, see why on the next slide

A

mutations

72
Q

Sometimes multiple mRNA ______ for the same amino acid so sometimes mutations in codons of mRNA (or DNA before it) do not cause changes in amino acids coded for or proteins made

A

codons

73
Q

diploid body cells made from mitosis

A

somatic cells

74
Q

haploid sex cells made from meiosis

A

gametes

75
Q

in genes in somatic cells COULD affect the proteins made by those genes, these mutations could be inherited if they affect many cells in the body due to how they are inherited, and can lead to evolution in a bad way

A

mutations

76
Q

based upon embryology)
discovered by Sean Carroll, evolutionary biologist
gametes of animals pass on master control genes to offspring that control the development of their body parts in the embryo during development, they are found in stem cells, the same master control genes are found in many animals

A

evolutionary development

77
Q

All cells of embryo/fetus originate from 1 zygote stem cell that undergoes mitosis (cell division)

All cells begin as undifferentiated cells

Then, the stem cells begin to differentiate and develop specific functions (AKA specialize) due to DNA and genes that are turned on in each cell

Form skin cells, bone cells, brain cells, etc

A

Embryological Development

78
Q

similar sequences of nucleotides in master control genes of different animals

A

Homeotic boxes (or homeoboxes)

79
Q

same genes found in many animals that control development of same structures/functions in all the animals that have it

A

master control genes

80
Q

examples of master control genes

A

hox genes

81
Q

are found in different animals and they form the same body part in each animal, but the body parts are adapted differently for each animal
ex. all animals have appendages but in humans they are arms and legs, in insects they are legs and wings and the legs look differently in each

A

Same master control genes or Hox genes

82
Q

Hox genes exist due to shared ______ ______ of animals during the Cambrian explosion when all animal species underwent divergent evolution, the same master control genes were inherited by all of them

A

common ancestory

83
Q

eye development

A

pax 6

84
Q

limb

development- antenna, legs, wings

A

Distal-less gene

85
Q

heart

development

A

tinman

86
Q

Mutations in _______ can be more serious than in somatic cells especially if they are in master control genes

A

gametes

87
Q

mutation in a ______________ (ex. distal less- dll) could be dangerous or deadly to offspring

A

master control genes

88
Q

are always inherited and thus can lead to evolution (in a good or bad way depending on the mutation and its effect)

A

Mutations in gametes and master control genes

89
Q

________ evolve, individuals do not

A

populations

90
Q

mutation
migration/gene flow
non-random mating- not included on CK-12 assignment but is in the video on the site
genetic drift/decrease in population size

As a result, these forces lead to…….
E. natural selection

A

yeah

91
Q

Mutations in DNA nucleotide sequences, especially of master control genes in gametes (ex Pax 6, Tinman, distal-less genes) lead to heritable changes such as legs growing from head, deformed heart, etc. (also mutations in other genes in gametes)

Mutations in DNA nucleotide sequences of regular genes of somatic cells CAN sometimes lead to heritable genetic variation too

Mutation is NOT a common thing to happen, so it does not significantly change allele frequency of a population, but is source of variation for the other forces of evolution

leads to genetic variation

A

mutaions in individuals

92
Q

(NOT included on the CK-12 site but is in the video on the site) does NOT necessarily lead to genetic variation but can still impact evolution

Random mating is different… Individuals choose mates regardless of how they look which leads to variation

When individuals choose mates that have the same phenotypes as them

This leads to inbreeding which leads to more individuals who are homozygous rather than heterozygous which maintains allele frequencies

A

non-random mating

93
Q

Sometimes individuals choose the mates with only certain phenotypes that are most “attractive” to them, sometimes this exaggerates phenotypes to the point of the trait becoming detrimental but can also lead to better “fitness”

A

random mating

94
Q

leads to genetic variation, sometimes in a bad way
andom drastic reduction in size of a small population

greatly affects small populations even if only 1 individual is lost since alleles may not be present in many individuals

Bottleneck effect- small number of individuals survive, thus choice of mates is greatly reduced, thus can cause change in allele frequencies

Population size dramatically decreased due to unusual event or reason such as chance events like epidemic, flood, overhunting, landslide, earthquake, fire, etc
Since population is quite small, if disease strikes after genetic drift, less ability to adapt and could become extinct

Can lead to inbreeding or interbreeding which decreases genetic variability and diversity, can bring out “bad genes”

A

genetic drift

95
Q

Surviving individuals repopulate which can change the allele frequencies especially if alleles or genes present in the population are already mutated
Then the allele frequency of future generations changes

A

results of genetic drift

96
Q

a few individuals start a new population in a different location

but the founder species could be have different allele frequencies than the population they left

A

founder effect

97
Q

mechanism’ for evolution in which nature ‘allows’ individuals that are best suited (most “fit”) with most favorable heritable variation to survive and reproduce and pass on genes and traits to their offspring thus leading to adaptations

Can increase or decrease allele frequency depending on its effects on survival and reproduction

Natural selection leads to microevolution of a species including divergent evolution, convergent evolution, adaptive radiation, etc

Can lead to macroevolution and speciation eventually though

A

natural selection

98
Q

leads to differences in “fitness” among individuals in a population

allows for adaptations to occur within the population

changes allele frequencies in the gene pool of the population

ex sickle cell anemia slide #21 in PPT 3 & slides #37-48 in PPT 6

A

natural selection

99
Q

natural selection depends on:

A

the phenotypes of the traits

the environment

100
Q

traits controlled by many genes

Exs. skin color, hair color, peppered moth wing color

Data represented as a “normal distribution”

A

polygenic traits

101
Q

is graphed as bell shaped curve

Mean= average values, includes middle values of graph

A

normal distribution

102
Q

One “extreme” from
normal bell shaped curve
is eliminated/selected against, other extreme is selected for

So curve moves to
the extreme that is
selected for, thus the “mean” shifts towards that extreme

A

directional selection

103
Q

Ex. Mammoths
with largest tusks selected for due to survival of the fittest

But tusks became so large that it could have lead to their extinction so then selected against large tusks

Ex. Spines of a cactus

More spines cactus has more likely to not be eaten by pig
Ex. Greyhounds

Artificially selected (bred) for greyhounds that are the fastes

ENVIRONMENTAL FORCES… LEAD TO EVOLUTIONARY CHANGE

Overuse of antibiotics causes bacteria to become resistant to them so now some antibiotics cannot protect us

‘The Rise of Antibiotic-Resistant Infections’

A

Directional Selection and specialization

104
Q

Problem with antibiotic resistant bacteria

A

MRSA

105
Q

Both “extremes” of bell curve are eliminated/selected against, “mean” or average phenotype is selected for

bell curve becomes more narrow since both extremes selected against and “mean” is selected for so “mean” gets larger

Ex. Human baby birth weights

Low birth weights and high birth weights are bad, both selected against and mean birth weight is selected for

ex. number of eggs a bird lays

A

stabilizing selection

106
Q

“Mean” of bell curve is selected against and “extremes” are selected for

graph ends up with two curves since both extremes selected for and “mean” gets lower since it is selected against

The more that palatable, or tasty, African butterflies mimic distasteful butterflies, the better chance the tasty butterflies have of surviving

Ex. sexual dimorphism- there is usually a difference in appearances between males and females in some species, males one extreme and females other extreme

A

disruptive selection

107
Q

fossils are preserved remains (bone, tooth, shells) or traces (footprints, burrow, or imprint) of an organism that lived long ago

A

fossil records

108
Q

are dated using radiometric dating (using half lives) (K-Ar or Ur-Pb or C14) so provides actual record of the evolution of Earth’s 3.5 billion yrs of life

A

fossils

109
Q

Can determine when the organism lived using the

Precambrian era, Paleozoic era, Mesozoic era, Cenozoic era and their respective geological periods

A

geological time scale

110
Q

an be used in addition to the fossil record to determine where organisms lived in the past ex Pangaea

A

plate tectonics

111
Q

which are fossils of extinct organisms found between ancestors to 2 groups of modern day groups, with traits of both, however some parts of the fossil record is incomplete

A

Missing links (or intermediate or transitional forms)

112
Q

using DNA’s nucleotide sequences and genes- look at how many amino acids are different between two species to determine relationship between proteins in those species
Ex hemoglobin

A

Amino acid sequences of proteins

113
Q

can be used to determine the similarity of DNA sequences between species especially those that share recent common ancestors
Ex gorillas and chimps with humans

A

DNA

114
Q

what? is a circular DNA plasmid inside the mitochondria
How it arose- mitochondria arose due to endosymbiosis of bacterial cells

Inherited from mother to children

mutates slower because plasmids replicate by binary fission when mitochondria replicate so DOES NOT change from one generation to the next except by spontaneous mutation (unlike nuclear DNA which genetically recombines every generation due to meiosis and sexual reproduction)

Use number of nucleotide changes (mutations) in DNA or amino acid changes in proteins to determine divergence between species

mtDNA can be used to: date or determine how long ago two individuals or species diverged from one another
Can be used to find common ancestors
mtDNA can be used to trace migration “Out of Africa” and for relationship between 2 species

called a “molecular clock” because it can be used to “tell time” when divergence of species occurred- used as a dating method

Each species’ mtDNA mutates at a fairly constant rate

Thought to have occurred very slowly??
Mitochondrial Eve- once thought that human mtDNA mutation occurred once every 200,000 years, now thought to be once every 6500 years
Problem is it cannot be directly (absolutely) measured

A

mtDNA

115
Q

Different animals have similar genes and thus similar body parts due to common ancestry
ex. hearts, eyes, and limbs of all animals and brains of vertebrates

A

Master control genes

116
Q

same basic pattern of parts due to similar embryological origins of the organisms
Similar basic structures (due to common ancestry), however… the functions MAY BE different or….. may be the same function too.

embo studies - Similar vertebrate embryological development due to common ancestry and divergent evolution

Results in homology

divergent evolution

A

Homologous structures

117
Q

Structures that have become reduced in size and function due to evolution
Evidence of common ancestry- creatures with that trait have a common ancestor that once used that organ

Evidence of homology and common ancestry

Ex halter(e)s in flies (hind wings)

A

Vestigial structures

118
Q

Structures are adapted to perform the same function in different organisms if they live in similar habitats but in different parts of the world
But structures evolved independently of one another because organisms not closely related
Ex. wings of animals all used for flight but made of different things

A

Analogous Structures

119
Q

Results in analogous structures

No evidence of recent common ancestry
Similar adaptations due to similar habitats in different places but evolve in different organisms independently
Demonstrates the power of natural selection

A

convergent evolutioon

120
Q

Evidences for Microevolution

‘change within a species’

A

Peppered moths

Sickle cell anemia

121
Q

is a protein that controls coloration of wings
Melanin is from a multigene family- many genes and many alleles control the production of melanin
Amount of melanin determined by the amount of alleles present
more alleles present for that gene, the more melanin is produced so the darker the moth
the less alleles present, the less melanin is produced so the lighter the moth
9 shades of peppered moths due to variations of melanin
If moth is camouflaged due to coloration, it is better adapted to the environment thus survives and reproduces and passes on genes for same number of alleles for melanin to offspring

A

melanin

122
Q

before 1850’s (prior to Industrial Revolution)= tree trunks were lightly colored
moths with most alleles for melanin were the darkest and were eaten due to lack of camouflage
So moths that had least and medium amts of melanin and #’s of alleles for melanin survived and reproduced
after 1850’s (due to Industrial revolution)= tree trunks became dark because of pollution from Industrial Revolution thus affected which moths survived which was called ‘industrial melanism’
moths with least alleles, had least melanin so were the lightest & were eaten due to lack of camouflage
moths with more alleles, had more melanin were darker thus were not eaten thus survived & reproduced

A

color of moths natural selection

123
Q

where is hemoglobin found? human RBC’s

normal RBC’s are anucleated in order to hold hemoglobin which carries oxygen

A

hemoglobin

124
Q

Inherited recessive trait due to mutation in one nucleotide of beta- hemoglobin gene

Causes RBC’s to sickle thus clogging vessels so oxygen does not get to cells

A

sickle cell amenia

125
Q

normal RBC’s (homozygous dominant)

normal RBC’s- no sickle cell anemia, but get malaria

A

AA

126
Q

normal RBC’s but carry sickle cell anemia trait (heterozygous)
ormal RBC’s but carry sickle cell anemia gene, but no malaria either

A

AS

127
Q

have sickle cell anemia (homozygous recessive)

sickled RBC’s so have sickle cell anemia, but no malaria

A

SS

128
Q

Since sickle cell anemia is fatal, then why hasn’t natural selection eliminated it’s alleles from the human population?

A

Having only one allele for sickle cell makes a person resistant to malaria in some parts of the world and malaria is more deadly than sickle cell

129
Q

If malaria is endemic

to certain areas…..

A

natural selection works on sickle cell allele in opposing ways

130
Q

Natural selection in areas where malaria is NOT endemic…

A

ickle cell allele is selected against in “SS” only, since it is deadly
“SS” allele frequency decreases in sickle cell homozygous (SS) individuals and they become less common
The most “fit” can be either “AA”
or “AS” since neither results in sickle cell anemia, (the sickle cell allele is maintained in the “AS” individual only even though “AS” is a carrier for sickle cell anemia)
Directional Selection- p 263

131
Q

Natural Selection in areas where malaria is endemic…

A

when malaria is present, “AA” and “SS” are selected against, and “AS” is selected for since it is most “fit”

Natural selection maintains both normal hemoglobin allele AND sickle cell allele in the “AS” individuals because…..

132
Q

he sickle cell allele in “SS” homozygous individuals is selected against and eliminated because sickle cell disease is lethal and “AA” is also eliminated or selected against because malaria is deadly
BUT….the sickle cell allele is preserved only in the heterozygous individuals (“AS”) because it provides resistance to both malaria and sickle cell anemia

Natural selection works in opposite directions= BALANCING SELECTION

A

Natural Selection in areas where malaria is endemic…

133
Q

Natural Selection in areas where malaria is endemic…

A

The allele frequencies balance out, only good to be “AS”

Balancing Selection - pp.262-263

134
Q

When microevolution occurs within many species that are interrelated, it causes macroevolution between the species where one of the interrelated species replaces another

A

evolution

Botany/Zoology (5 decks)

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