Station 11

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Station 11
Reporting Category 3 Biological Evolution and
Classification

• Natural Selection and Adaptation

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Essential Question Bell Ringer

• How can natural selection affect the frequency of
  the occurrence of certain traits in a population
  over many generations?

Through the process of natural selection, certain
traits of organisms that are able to adapt to
changing conditions in an ecosystem or biome
become more prevalent and are more likely to be
passed on to the organisms offspring. Traits
that are not beneficial to an organism are less
likely to be passed on to successive generations,
and organisms that are not as fit are less likely
to pass on their traits to successive generations.
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Pre-Preview Question

• During his visit to the Galapagos Islands,
  Charles Darwin discovered 14 distinct species of
  finches. These groups had been geographically
  isolated from one another. Many of them lived on
  different islands. The species of finches
  differed mainly in feeding behavior, beak
  structure, and body size. Yet, all of the species
  shared some characteristics.
• Which of the following statements best explains
  differences between the finches?
• The beaks of the finches changed so the finches
  could better access different sources of food.
• The beaks of the finches changed so all of the
  finches could eat the same types of food.
• The beaks of the finches changed as the species
  of finches migrated to the same island.
• The beaks of the finches changed as the finches'
  body sizes changed.

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Pre-Review Question

• The forelimbs of a frog and a horse are examples
  of structures that are
• Heterotrophic
• Homozygous
• Hermaphroditic
• Homologous

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Pre-Review Question

• In an area of Indonesia where the ocean floor is
  littered with empty coconut shells, a species of
  octopus has been filmed "walking" on two of its
  eight tentacles. The remaining six tentacles are
  wrapped around its body. Scientists suspect that,
  with its tentacles arranged this way, the octopus
  resembles a rolling coconut. Local predators,
  including sharks, seem not to notice the octopus
  as often when it behaves in this manner. This
  unique method of locomotion has been utilized by
  successive generations of octopi through 
• Selective breeding of the octopus species
• Competition between octopi and their predators
• The process of natural selection
• Ecological succession in marine habitats

6
Use this information to answer the question on
the next slide.
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Using the chart on the previous slide, write and
answer this question in your journal.

• Which cottontail rabbitA, B, or Cin the table
  above is considered the most fit of the three
  rabbits? Support you answer with data from the
  table.

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Copy this chart into your journal and fill in the
example information using the pictures on the
next slide.
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The Springbok antelope and the Pronghorn antelope
are examples of convergent evolution. The seals
flipper and the birds wing are examples of
divergent evolution. The Yucca plant and the
Yucca moth are examples of coevolution.
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Discuss with your partner.

• Read and discuss the definitions of biological
  influences and physical influences in the
  glossary. Explain the role that biological and
  physical influences play in natural selection and
  the effect these influences can have on an
  ecosystems populations and species.

Biological influences such as diseases may cause
weaker organisms to die out and prevent the
passage of their traits to other generations of
organisms. Physical influences such as a tsunami
may remove food sources for organisms or destroy
entire ecosystems. Different organisms may
repopulate the emerging, ecosystem changing the
direction of evolution or type of evolution from
the previous one.
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Discuss with your partner.

• What is the difference between the cactus on the
  left and the cactus on the right?

The cactus on the left is covered with spines or
needles the one on the right does not have them.
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Discuss with your partner.

• What effect does the deers feeding behavior have
  on the ability of each type of cactus to survive
  and reproduce?

The deer feeds only on the spineless cactus. Over
time, if the deer reproduces successfully, the
spineless cactus will no longer be part of the
desert biome, leaving only the cactus with spines
to reproduce. If the deer cannot find another
food source or does not have traits that enable
it to adapt, it must leave the biome or possibly
become extinct.
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Discuss with your partner.

• How does the deers feeding behavior with respect
  to the cacti in this desert biome illustrate
  natural selection or the survival of the fittest?

In order for natural selection to occur, it must
meet three conditions variations in
characteristics, differences in fitness, and
heritable traits The two cacti met these
conditions They had variations in their
characteristicsone with spines, one without.
They had variations in their abilities to survive
and reproducethe deer ate both the spineless
cactus pad and its flowers, meaning it couldnt
reproduce. The trait of spinelessness therefore
cannot be passed down to successive generations
and is therefore no longer heritable.
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I need to remember..

• No organism or population of organisms is
  perfectly adapted to its ecosystem.
• Natural selection does not produce perfection in
  the organisms that are adapted to an ecosystem.
• Adaptations are due to genes that are heritable.
• Natural selection occurs as the result of three
  conditions variations in
• characteristics in a population, heritable
  traits, and differences in fitness among
  organisms within a species.
• Survival of the fittest does not refer to how
  physically fit or strong an organism is rather,
  it refers to an organisms ability to reproduce
  and pass on its traits to the next generation.
• Natural selection does not act on an individual
  to make it better adapted to its environment.
• There are biological and physical influences that
  determine the survival and success of organisms.
• There are three types of evolution that occur as
  a result of natural selection divergent
  evolution, convergent evolution, and coevolution.

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Post Review Question

• A population of mosquitos is sprayed with a new
  insecticide. Most of the mosquitos are killed
  but a few survive. In the next generation, the
  spraying continues, but still more are immune to
  the insecticide. How could these results be
  explained according to the present concept of
  evolution?
• A. The insecticide caused a mutation in the
  mosquitos.
• B. The mosquitos learned to fight the
  insecticide.
• C. A few mosquitos in the first population were
  resistant and transmitted this resistance to
  their offspring.
• D. The insecticide caused the mosquitos to
  develop an immune response which was inherited.

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Post Review Question

• According to the theory of natural selection, why
  are some individuals more likely than others to
  survive and reproduce?
• Some individuals are better adapted to their
  environment than others.
• Some individuals pass on to their offspring new
  characteristics they have acquired during their
  lifetimes.
• Some individuals do not pass on to their
  offspring new characteristics they have acquired
  during their lifetimes.
• Some individuals tend to produce fewer offspring
  than others in the same environment.