Unit 7: Natural Selection
TOPIC 7.1 Introduction to Natural Selection
ENDURING UNDERSTANDING EVO-1 Evolution is characterized by a change in the genetic makeup of a population over time and is supported
by multiple lines of evidence.
LEARNING OBJECTIVE
EVO-1.C Describe the causes of natural Each population has natural variations in phenotype. What phenotype would of each pair would allow
selection. an organism to best survive each environment?
What limited resource How would this differential
ESSENTIAL KNOWLEDGE
Circle the might this phenotype help survival impact the next
EVO-1.C.1 Natural selection is a major
Environment phenotype the organism get more of? generation of these organisms?
mechanism of evolution.
Sunlight is the limited This adaptation helps next
EVO-1.C.2 According to Darwin‘s theory Shady forest: Plant with large resources here. In order to generation to get more adapted
of natural selection, competition for leaves or deep obtain maximum sunlight to even severe shade conditions.
limited resources results in differential roots? and photosynthetic rate, the Eventually, their next generation
survival. Individuals with more favorable plants have larger leaves for will have high photosynthetic
phenotypes are more likely to survive and max surface area. rate even in lower sunlight.
produce more offspring, thus passing traits
to subsequent generations. As swampy areas are much Water living capabilities will be
Island with Mammal with water filled, the organism increased in next generations.
swampy webbed feet or needs to swim. So, they will
LEARNING OBJECTIVE marshes: thick fur? have webbed feet.
EVO-1.D Explain how natural selection
affects populations. Sharp claws help them to Much evolved claws and high
Snowy Fox with sharp catch their pray and for metabolic rate to keep
ESSENTIAL KNOWLEDGE tundra: claws or a long speedy running in the snow. homeostasis will be evolved in
EVO-1.D.1 Evolutionary fitness is tail? next generations.
measured by reproductive success.
Consider two lizards. One lizard lived 5 years, had 25 offspring, and died of old age. The other lizard
EVO-1.D.2 Biotic and abiotic was eaten by a bird at 3 years old, and had 30 offspring. Which lizard was more fit? Why?
environments can be more or less
stable/fluctuating, and this affects the rate The lizard that lived 3 years and had 30 offspring was more fit because it has a greater ability to
and direction of evolution; different increase offspring and to descend its genes to the next generation.
genetic variations can be selected in each
generation
© Science of Curiosity©
, Unit 7: Natural Selection
TOPIC 7.2 Natural Selection
ENDURING UNDERSTANDING EVO-1 Evolution is characterized by a change in the genetic makeup of a population over time and is supported
by multiple lines of evidence.
LEARNING Plant species A is stimulated to produce flowers in response to warming weather in the Spring. Plant species B is
OBJECTIVE stimulated to produce flowers when hours of daylight become longer in the Spring. Which species would be most
EVO-1.E Describe the affected by the selective mechanism of Climate Change? Explain your reasoning.
importance of phenotypic
variation in a population.Plant species A is stimulated to produce flowers in response to warming weather in the Spring whereas plant species B
is stimulated to produce flowers when hours of daylight become longer in the Spring. Climate fluctuations occur a lot
ESSENTIAL during the Spring season. The weather changes and swings between warm and chilling temperatures. Bright sunshine
KNOWLEDGE in a week can be followed by a colder environment many times. In fact, weather can also be altered immensely even on
EVO-1.E.1 Natural the same day. Whatever be the weather conditions during the spring season, one thing is for sure, that is the daylight,
selection acts on Earth rotates on its axis in 24 hours, so we have a day of 12 hours followed by a night of 12 hours. Even if the weather
phenotypic variations in is chilling, daylight will occur, just its intensity will be weak. So, climate change will affect plant species A more
populations. compared to plant species B, because plant species A needs warmer temperatures during the spring season for
blooming, but it's not necessary that it's always good warmer weather during this season. As far as species B is
EVO-1.E.2 Environments concerned, daylight will always be there whether the temperature is cold or warm in seasons, so species B will have
change and apply less effect than species B.
selective pressures to
populations. A farmer uses DDT to kill insects in his field. The first year
nearly all of the insects were killed. By the fourth year,
EVO-1.E.3 Some however, nearly all of the insects survived the DDT
phenotypic variations treatment.
significantly increase or Explain the process of natural selection in this population of
decrease fitness of the insects. Include these words - mutation, phenotype,
organism in particular variation, resistance, adaptation, and differential
environments. survival.
ILLUSTRATIVE Natural selection is the process in nature by which
EXAMPLES organisms better adapted to their environment tend to
§ Flowering time in survive and reproduce more than those less adapted to their
relation to global climate environment. simple words- This variation means that some
change § Peppered moth individuals have traits better suited to the environment than
§ Sickle cell anemia § others. For example, treefrogs are sometimes eaten by
© Science of Curiosity©
, DDT resistance in insects snakes and birds. Four conditions are needed for natural selection to occur: reproduction, heredity, variation in fitness
or organisms, variation in individual characters among members of the population. If they are met, natural selection
automatically results.
Natural selection acts on an organism's phenotype or observable features. Phenotype is often largely a product of
genotype (the alleles, or gene versions, the organism carries).
Differential reproduction allows some organssms to survive and reproduce while others are not able to. natural
selection operates only by differential reproductive success. Differential mortality can be selective but only to the
degree that it creates differences between individuals in the number of reproductive progeny they produce.
Natural selection leads to adaptation, that is, to a population dominated by organisms that are anatomically,
behaviorally, and physiologically well suited to survive and reproduce in a specific environment. Resistance towards
DDT is a consequence of evolution via natural selection. The fertilizer or chemical or antibiotics action is an
environmental pressure; DDT which has a mutation allowing them to survive will live on to reproduce. They will then
pass this trait to their offspring, which will be a fully resistant generation.
Unit 7: Natural Selection
TOPIC 7.3 Artificial Selection
ENDURING UNDERSTANDING EVO-1 Evolution is characterized by a change in the genetic makeup of a population over time and is supported
by multiple lines of evidence.
LEARNING OBJECTIVE
EVO-1.F Explain how humans Artificial Selection - BBC Article about Domesticating Foxes tinyurl.com/hvnjbt9
can affect diversity within a Describe the difference between attempting to tame a single wild fox and breeding a
population. population of domestic foxes.
ESSENTIAL KNOWLEDGE The main difference between attempting to tame a wild fox and breeding the domesticated ones is their
EVO-1.F.1 Through artificial behavior change. While taming will only change the wild foxes' friendliness, breeding will change both
selection, humans affect behavior and morphological traits. According to the article, breeding will also change their skeletal
variation in other species. system, forming an entirely new generation with short legs, tail, snout, upper jaw, and floppier, drooping
ears. Ideally, taming will not bring genetic changes, but breeding will mix the hormonal and
neurotransmitter effects on the foxes. This implies that the behavior change caused by taming is reversible
LEARNING OBJECTIVE when the fox is allowed into the wild. Meanwhile,breeding will have permanent changes in the foxes'
behavior because breeding changes the
© Science of Curiosity©
TOPIC 7.1 Introduction to Natural Selection
ENDURING UNDERSTANDING EVO-1 Evolution is characterized by a change in the genetic makeup of a population over time and is supported
by multiple lines of evidence.
LEARNING OBJECTIVE
EVO-1.C Describe the causes of natural Each population has natural variations in phenotype. What phenotype would of each pair would allow
selection. an organism to best survive each environment?
What limited resource How would this differential
ESSENTIAL KNOWLEDGE
Circle the might this phenotype help survival impact the next
EVO-1.C.1 Natural selection is a major
Environment phenotype the organism get more of? generation of these organisms?
mechanism of evolution.
Sunlight is the limited This adaptation helps next
EVO-1.C.2 According to Darwin‘s theory Shady forest: Plant with large resources here. In order to generation to get more adapted
of natural selection, competition for leaves or deep obtain maximum sunlight to even severe shade conditions.
limited resources results in differential roots? and photosynthetic rate, the Eventually, their next generation
survival. Individuals with more favorable plants have larger leaves for will have high photosynthetic
phenotypes are more likely to survive and max surface area. rate even in lower sunlight.
produce more offspring, thus passing traits
to subsequent generations. As swampy areas are much Water living capabilities will be
Island with Mammal with water filled, the organism increased in next generations.
swampy webbed feet or needs to swim. So, they will
LEARNING OBJECTIVE marshes: thick fur? have webbed feet.
EVO-1.D Explain how natural selection
affects populations. Sharp claws help them to Much evolved claws and high
Snowy Fox with sharp catch their pray and for metabolic rate to keep
ESSENTIAL KNOWLEDGE tundra: claws or a long speedy running in the snow. homeostasis will be evolved in
EVO-1.D.1 Evolutionary fitness is tail? next generations.
measured by reproductive success.
Consider two lizards. One lizard lived 5 years, had 25 offspring, and died of old age. The other lizard
EVO-1.D.2 Biotic and abiotic was eaten by a bird at 3 years old, and had 30 offspring. Which lizard was more fit? Why?
environments can be more or less
stable/fluctuating, and this affects the rate The lizard that lived 3 years and had 30 offspring was more fit because it has a greater ability to
and direction of evolution; different increase offspring and to descend its genes to the next generation.
genetic variations can be selected in each
generation
© Science of Curiosity©
, Unit 7: Natural Selection
TOPIC 7.2 Natural Selection
ENDURING UNDERSTANDING EVO-1 Evolution is characterized by a change in the genetic makeup of a population over time and is supported
by multiple lines of evidence.
LEARNING Plant species A is stimulated to produce flowers in response to warming weather in the Spring. Plant species B is
OBJECTIVE stimulated to produce flowers when hours of daylight become longer in the Spring. Which species would be most
EVO-1.E Describe the affected by the selective mechanism of Climate Change? Explain your reasoning.
importance of phenotypic
variation in a population.Plant species A is stimulated to produce flowers in response to warming weather in the Spring whereas plant species B
is stimulated to produce flowers when hours of daylight become longer in the Spring. Climate fluctuations occur a lot
ESSENTIAL during the Spring season. The weather changes and swings between warm and chilling temperatures. Bright sunshine
KNOWLEDGE in a week can be followed by a colder environment many times. In fact, weather can also be altered immensely even on
EVO-1.E.1 Natural the same day. Whatever be the weather conditions during the spring season, one thing is for sure, that is the daylight,
selection acts on Earth rotates on its axis in 24 hours, so we have a day of 12 hours followed by a night of 12 hours. Even if the weather
phenotypic variations in is chilling, daylight will occur, just its intensity will be weak. So, climate change will affect plant species A more
populations. compared to plant species B, because plant species A needs warmer temperatures during the spring season for
blooming, but it's not necessary that it's always good warmer weather during this season. As far as species B is
EVO-1.E.2 Environments concerned, daylight will always be there whether the temperature is cold or warm in seasons, so species B will have
change and apply less effect than species B.
selective pressures to
populations. A farmer uses DDT to kill insects in his field. The first year
nearly all of the insects were killed. By the fourth year,
EVO-1.E.3 Some however, nearly all of the insects survived the DDT
phenotypic variations treatment.
significantly increase or Explain the process of natural selection in this population of
decrease fitness of the insects. Include these words - mutation, phenotype,
organism in particular variation, resistance, adaptation, and differential
environments. survival.
ILLUSTRATIVE Natural selection is the process in nature by which
EXAMPLES organisms better adapted to their environment tend to
§ Flowering time in survive and reproduce more than those less adapted to their
relation to global climate environment. simple words- This variation means that some
change § Peppered moth individuals have traits better suited to the environment than
§ Sickle cell anemia § others. For example, treefrogs are sometimes eaten by
© Science of Curiosity©
, DDT resistance in insects snakes and birds. Four conditions are needed for natural selection to occur: reproduction, heredity, variation in fitness
or organisms, variation in individual characters among members of the population. If they are met, natural selection
automatically results.
Natural selection acts on an organism's phenotype or observable features. Phenotype is often largely a product of
genotype (the alleles, or gene versions, the organism carries).
Differential reproduction allows some organssms to survive and reproduce while others are not able to. natural
selection operates only by differential reproductive success. Differential mortality can be selective but only to the
degree that it creates differences between individuals in the number of reproductive progeny they produce.
Natural selection leads to adaptation, that is, to a population dominated by organisms that are anatomically,
behaviorally, and physiologically well suited to survive and reproduce in a specific environment. Resistance towards
DDT is a consequence of evolution via natural selection. The fertilizer or chemical or antibiotics action is an
environmental pressure; DDT which has a mutation allowing them to survive will live on to reproduce. They will then
pass this trait to their offspring, which will be a fully resistant generation.
Unit 7: Natural Selection
TOPIC 7.3 Artificial Selection
ENDURING UNDERSTANDING EVO-1 Evolution is characterized by a change in the genetic makeup of a population over time and is supported
by multiple lines of evidence.
LEARNING OBJECTIVE
EVO-1.F Explain how humans Artificial Selection - BBC Article about Domesticating Foxes tinyurl.com/hvnjbt9
can affect diversity within a Describe the difference between attempting to tame a single wild fox and breeding a
population. population of domestic foxes.
ESSENTIAL KNOWLEDGE The main difference between attempting to tame a wild fox and breeding the domesticated ones is their
EVO-1.F.1 Through artificial behavior change. While taming will only change the wild foxes' friendliness, breeding will change both
selection, humans affect behavior and morphological traits. According to the article, breeding will also change their skeletal
variation in other species. system, forming an entirely new generation with short legs, tail, snout, upper jaw, and floppier, drooping
ears. Ideally, taming will not bring genetic changes, but breeding will mix the hormonal and
neurotransmitter effects on the foxes. This implies that the behavior change caused by taming is reversible
LEARNING OBJECTIVE when the fox is allowed into the wild. Meanwhile,breeding will have permanent changes in the foxes'
behavior because breeding changes the
© Science of Curiosity©
