Name: Sariah C.

PT 6.2: Speciation Case Study

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Learning Target
(HS-LS4-5) I can evaluate evidence that changes in the environment may lead to
larger populations, new species, or extinction.

Guiding Questions
What environmental factors were necessary for speciation to occur among
the mosquito population?
How did this impact the mosquito’s chances of survival?

Background
A species is defined as a population or group of populations whose
members interbreed and produce fertile offspring. The changes in the
environment, which can come from natural or human causes, can
contribute to the increase of a species’ populations, the creation of
new species, or the decline and eventual extinction of a species.

Case Study - When the London underground tunnels were being constructed in the 19th
century, some above-ground mosquitos migrated underground and adapted to a subterranean
environment. Research articles will present evidence of how the changes in their environment
eventually led to a new species of underground mosquito that is unable to breed with the
above-ground mosquitoes. You will develop your own argument as to how a new species of
mosquitoes emerged.

Task 1 - Vocab Review

DIRECTIONS: Answer the following questions. Refer to your PT 6.2 notes for the answers.

1. Genetic variation within a population is referred to as what? Gene pool

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 2. Gene flow is the movement of ______ from one population to Alleles
another.

3. What is another word for gene flow? Migration

4. Genetic drift increases genetic diversity. (TRUE/FALSE) False

5. What is the term for when two or more species arise from one Speciation
existing species?

6. What is the final step of speciation? Reproductive

isolation of
populations.

7. Isolation caused by physical barriers. Geographic isolation

8. Isolation caused by time. Temporal isolation

9. Isolation caused by differences in mating. Behavioral isolation

10. The moment of extinction is considered to be the death of the Last individual.
_____ ____________ of the species.

Task 2 - Analyzing Case Studies

DIRECTIONS: Read the following case studies (Article A & Article B) and answer the questions
below. You will find the answer to each question in the section stated.

ARTICLE A : The London Underground Has Its Own Mosquito Subspecies

Section Question

1. How did the mosquito subspecies Culex pipiens molestus come about?
The mosquito subspecies Culex pipiens molestus came to be over the
1 underground 150 year history of the London underground.

2. Which evolutionary process did the new subspecies of mosquito achieve in

the subway tunnels?
The evolutionary process that the new subspecies of the mosquito
achieved in the subway tunnels was reproductive isolation.

3. What is speciation?
Speciation is the process by which animals evolve into a completely
new species from each other.
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4. Why is there doubt that the London Underground is the only subway system

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 that has a new subspecies of mosquitoes?
There is doubt because a mysterious invasion of the mosquitoes was
found in New York sewers.

ARTICLE B : The Unique Mosquito that Lives in the London Underground

Section Question
1. What did researcher Katherine Byrne discover to be the key difference
between the Culex pipiens and the isolated Culex pipiens molestus?
What researcher Katherine Bryne discovered to be the key difference
was that they were fundamentally different from their surface-dwelling
relatives. Culex pipiens only bit birds but the Culex pipiens molestus
had a taste for human blood.
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2. What are three traits that are unique to the Culex pipiens molestus?
Three traits that are unique to the Culex pipiens molestus are, they
behave in a different way, they don’t need blood to mate and they don’t
require a lot of space to mate.

3. Over time, the mosquitoes developed new behaviors and features as a

result of their environment. These changes are known as ________________.
Adaptations to a subterranean life.

4. As a result of isolation over many generations, the Culex pipiens molestus

are no longer able to do what?
The Culex pipiens molestus are so distinct they are no longer able to
interbreed with other mosquitoes.

5. The tunnels were sealed off, creating a physical barrier and thereby
reproductive isolation. What type of evolution occurred as a result?
This caused divergent evolution. Divergent evolution is when two
species evolve to become more and more different from each other.
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6. Evolution usually happens slowly. How long did it take for the speciation of
London mosquitoes to occur and why did it happen so fast?
It took just a few hundred generations for the speciation of London
mosquitoes to occur. It happened so fast because with one species
breeding above ground and the other below, the stage was set for a
new subspecies to evolve.

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 7. What could be an alternative explanation for the origin of Culex pipiens
molestus?
The alternative explanation for the origin of Culex pipiens molestus is
that it was brought in from the fruit movement and the freight into the
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docks of London.

8. Why does Reznick feel that London is the birthplace of the Culex pipiens
molestus?
Reznick feels that London is the birthplace of the Culex pipiens
molestus because he argues that there is a number of genetic factors
that suggest that the mosquito was first evolved in london.

9. Fill in the blanks: “ A few hundred years in the _________________

_________________ can form a new _________________ ,” says Reznick.

Right circumstances Species

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10. Is a physical barrier necessary to speed up the process of speciation? Give
an example of an organism that is proof of this.
A physical barrier is not needed to speed up the process of speciation.
Marine and freshwater sticklebacks are a proof of this theory.

Task 3 - Reflection Questions

1. The mosquitoes in London’s underground became a new species. TRUE/FALSE
True

2. Going underground and drifting out to sea are examples of isolation. TRUE/FALSE
False

3. What environmental factors were necessary for speciation to occur among the mosquito
population?
The species of mosquitoes had to be geographically isolated from each other.

4. How is reproductive isolation evidence for the speciation of the mosquito population?
Reproductive isolation is evidence for the speciation of the mosquito population
because the underground mosquitoes are not able to breed with other mosquitoes.

5. What are the key adaptations (advantageous traits) unique to the underground mosquito
compared to the above ground mosquitos?
Key adaptations are that since the underground mosquito lived underground there

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 was no way to tell seasons, they mated in closed areas because they had lost their
tendency to hibernate in winter since they couldn’t tell what season it was.

6. Would it have been possible for the mosquitos to speciate if they weren’t geographically
isolated? Explain why.
I think that it wouldn’t have been possible for the mosquitoes to speciate if they
weren’t geographically isolated because then the underground mosquito wouldn't
have become its own species, it would've just turned into the same species of the
above ground mosquito which ruins the whole point of speciation. Being
geographically isolated gave the underground mosquitoes different traits making it a
new species.

Task 4 - Writing Prompt

Directions: Research the answer then write 2-3 paragraphs (5-7 sentences each) that
answers the following question:
How do humans drive speciation as well as extinction in organisms?

YOU MUST CITE YOUR SOURCE(S)!! Be sure to include links to websites where you gathered your
information at the end of your paragraph.

Humans drive speciation to organisms in many ways. Humanity has been found to be actually
well effective with speciation, just like humanity can help speciation it can also ruin it and
cause it extinction. Speciation happens when a group of organisms or species separates from
its own and creates a new and different species. This happens with isolation. There are
different types of isolations like geographic isolation, behavioral isolation and temporal
isolation. These all have different effects but still create different species. So as you can
imagine humans can be a big factor when it comes to speciation. One example is the
introduction of a new habitat from a human to a species can be one cause of speciation.

A lot of times the way humans can bring speciation to an organism is the same way it can
bring extinction. So sometimes humans can be helpful to speciation but they can also be
harmful. One example I found was “ Invasive species can out-compete natives and drive them
to extinction. But the new environment in which animals and plants find themselves, and their
isolation from other populations, can encourage morphological changes to develop, as well.”
as stated in the article “how humans create as well as destroy species” by mongabay. Another
way humans can cause extinction is hunting or poaching. This has caused several problems
with species and extinction. With one species gone it’s impossible to create speciation of that
species. WIthout speciation of a species the whole population of genes from that species dies
out or becomes extinct therefore having the species no longer exist.

MASTERY RUBRIC AND COMPLETION CHECKLIST

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 Learning Target
(HS-LS4-5) I can evaluate evidence that changes in the environment may lead to
larger populations, new species, or extinction.

Guiding Questions
1. What factors were necessary for speciation to occur among the mosquito population?
2. How did this impact the mosquito’s chances of survival?

1 Concerns (2) Goal Achieved (3) Exceeded Mastery (4)

(Similar to a C) (Similar to a B or B+) (Similar to an A or A+)
1) Topic and Content
A score of 2 means you My argument has a ❏ Real-world examples or
applications used not from the
did everything you were knowledgeable and
class activity.
supposed to but your thoughtful response to ❏ Supported my argument with
answer may have used the learning target(s) and information that was not
some vocabulary guiding question(s). provided in class and cited
incorrectly or your use correctly.
of evidence was unclear 2) Use of Evidence and ❏ Used all score 4 vocabulary.
or missing some Analysis
You need at least 3 boxes
important details. My argument is
checked from the above
supported by
boxes to have a chance at
information from the
earning a grade of 4 if you
provided class resources
got a 3 on everything else.
and class activities.

IMPORTANT! Any information used that is NOT learned from class MUST be
cited or you will have to redo the entire assignment! If you google it, you must
use YOUR OWN WORDS.
Required Vocabulary: If you do not use ALL of the Score 2 words you will get
ZERO CREDIT.

Score 2 Words Score 3 Words Score 4 Words

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● Genes ● Reproductive Isolation ● Reproductive Isolation
● Genetic Drift ● Divergent Evolution ● Divergent Evolution
● Speciation ● Geographic isolation ● Geographic isolation
● Species ● Genes ● Natural Selection
● Genetic Drift ● Genes
● Species ● Genetic Drift
● Speciation ● Species
● Speciation
● Alleles
● Founder Effect