The Journals of Charlotte Durand, Explorer – Teacher notes
From World Wildlife Fund’s Windows on the Wild: Biodiversity Basics
Before you begin:
For each student, make one copy of "The Journals of Charlotte Durand, Explorer", the "Twitomite Table",
the "Twitomites: What Do You Think?" questions, and the optional "Twitomite Time Line".
What to do:
1. Discuss Charles Darwin and his research.
Begin by asking students what they know about Charles Darwin and his research. When students have shared
as much as they know, explain that Charles Darwin, an English naturalist, sailed on a voyage of the HMS
Beagle to survey the natural history of the west coast of South America and some Pacific Islands. In 1835 he
surveyed the Galapagos Islands where, among other things, he observed and collected nine different types of
finches, small birds found in many parts of the world. Darwin wondered why there were so many different
kinds of finches on the islands. And in his attempt to explain why, he came up with one of the first theories
of evolution by natural selection. As we now know, there are 13 different species of finches in the
Galapagos, and all of them are believed to have descended from a common ancestral species that probably
arrived in the Galapagos from South America some 100,000 years ago.
Explain that in this activity, the students are going to do some of the same kind of detective work that
biologists such as Darwin have done to understand the evolutionary history of organisms. In other words,
they'll look at biological and geological clues to see if they can figure out why and how an ancestral creature
evolved into a number of distinct species.
2. Hand out “The Journals of Charlotte Durand” and the "Twitomite Table”
Tell the students that you've given them the journals of a fictional 19th century explorer who describes a
group of lizards she finds on an imaginary island chain off the west coast of Mexico. For homework, ask the
students to read the journals, look at the accompanying sketches, and fill out the 'Twitomite Table".
3. Discuss homework assignment.
In your next session, discuss any questions the students have about their homework assignment. Then divide
them into pairs and ask them to compare their answers on the 'Twitomite Table." After the students have
come to a consensus on their answers, have them edit any parts of the table that they think they filled out
incorrectly the first time.
4. 4. Hand out "Twitomites: What Do You Think?" and the "Twitomite Time line."
Working in their pairs, have the students use the journal, table, and time line to answer the "Twitomites:
What Do You Think?" questions.
5. Share results.
Discuss the answers to these questions as a group. The questions will encourage the students to think about
and compare how the different twitomites might have evolved.
1. How many species of twitomites were there 20,000 years ago? Were the individual twitomites
genetically identical? Explain. (Twenty thousand years ago, there was just one species of twitomite.
2.
3.
4.
5.
Individuals were not genetically identical because, even within a population, individuals have a lot of
genetic variation.)
When did the twitomites first become separated into three distinct populations? Do you think the
twitomite populations on the three islands were fairly similar or radically different at first? (The three
populations would have formed 10,000 years ago when the peninsula became separated into three
islands. At first the populations were probably quite similar because they'd so recently been part of
the same large population.)
Over time, what could have caused different species of twitomites to arise on each of the three
islands? Be specific. (Three distinct species could have arisen because the populations were isolated
and because their selective pressures and habitats-shrubby desert, sandy beach, and forest-were
different, making different traits more advantageous for individuals on each of the three islands.)
What had happened to the islands by the time the explorers arrived? How did this affect the
twitomites? (The three islands separated into seven distinct islands. Once again the twitomites were
divided into even more populations, and each population inhabited a different kind of habitat.)
Explain how each of the eight twitomites is particularly well adapted to its habitat. (Many of the
twitomites' adaptations helped them find food. The different snouts gave certain species the ability to
feed on the most abundant type of food in their habitat. The green twitomite was specially adapted to
hide from predators through camouflage. The marine twitomite had webbed feet that helped it feed
on marine creatures and get around more easily in its beach and marine habitat.)
6. Some scientists think about the process of speciation in terms of this formula:
isolation + time + evolution = speciation.
Apply this formula to the twitomites to explain how their single ancestor evolved into eight different
species. (First there was one common twitomite ancestral species 700,000 years ago, but then the sea
level rose to divide the peninsula where the twitomites lived into smaller and smaller pieces of land.
Because none of the twitomites was equipped to swim long distances, the separation of the islands by
water prevented the populations on the different islands from intermixing. This element provided the
"isolation" part of the formula. Also, because the islands were separated for 10,000 years, the twitomites
were isolated for a long period of time. This element accounts for the "time" part of the formula. Finally,
the twitomites in each habitat adapted to new conditions. Like the birds in Part I of the activity. the
twitomites in different areas developed certain traits that helped them thrive in their habitat-beach, desert,
or forest. Natural selection occurring over a long period of time on each of the islands led to evolution and
speciation of each of the different groups of twitomites. Each of the species is adapted to survive in its
habitat.)
6. Review concepts.
Once students have had a chance to discuss their answers, review the major concepts of the activity.
Can anyone clearly answer the question posed at the beginning of Part I: How do new species
develop?
Ask the students to list again some of the key factors necessary for evolution (genetic variation
among individuals in a population, selective pressures, time, and so on). Then see if they can apply
their understanding to the more advanced questions posed below.
How does evolution affect biodiversity? (Through the process of natural selection, an incredible
diversity of species has evolved on Earth.)
What effect will declining biodiversity have on the process of natural selection in the future? (With
many species' populations declining, there is much less genetic variety for natural selection to "work
with." Fewer individuals mean less genetic diversity in the population. Without a wide range of
genetic traits in a population, there is less chance that enough individuals will have the traits
necessary for survival. Rather than adapting to environmental changes, small populations of animals
could die out, accelerating the loss of biodiversity.)
What can we do to help protect and conserve biodiversity, and the processes of natural selection and
evolution? (We can protect biodiversity by maintaining large, diverse populations of species
throughout the world by protecting species' habitats, keeping introduced species from outcompeting
native species, preventing pollution from harming living things, and responsibly managing wild
populations of plants and animals we use for food, clothing, medicines, and other products.)
Assessment
Have each student "create" an insect or other creature that would live in his or her bedroom. Assume it is a
species that rapidly adjusts to change through evolution. The students should describe how their rooms may
change over time and how the insects or creatures would evolve to survive the changes. This assignment can
be done as either a series of pictures (cartoon or storyboard) or a written story.
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Unsatisfactory-The student does not demonstrate an understanding of evolutionary change.
Satisfactory-The student provides one example of how changing selective pressures affect evolution.
Excellent-The student uses creativity and logic in determining multiple evolutionary outcomes as the room
changes.
Portfolio
The students can write comments on their reactions to the evolution simulation game (Part I).Collect the
comments for portfolios. The "Twitomite Table" and answers to "Twitomites: What Do You Think?" can
also be part of the portfolio.
Writing Idea
Have the students keep a journal describing the unique features of some of the plants, animals, or other living
things in their own backyard or neighborhood. Tell the students to spend a few days looking closely at
several species from one major group (mammals, insects, flowering plants, and so on) as they encounter the
organisms around the yard or neighborhood. Ask the students to write about how they imagine the distinct
species within these groups could have evolved from similar ancestors. They should think about what kinds
of selective pressures influenced these species and look for adaptations these animals or plants have
developed over time.
Extensions
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For a real-life example of how evolution and speciation occur, hand out copies of "The Case of the
Peppered Moth" (page 60 in the Student Book). Tell the students to read the paragraph to themselves
and answer the ''Think It Over" questions. Then review their answers as a group. Be sure the students
understand that the peppered moths always had a range of coloration (much as humans can be fair
skinned or dark skinned or something in between) but that changing environmental conditions gave
an advantage to darker-colored moths for many years.
o Emphasize that natural selection can operate on any genetic trait-including color, size, body
shape, and behavior (such as ways of obtaining food)-that influences the survival of a species.
Have your students research Charles Darwin and Alfred Wallace. How did they "discover"
evolution? Which one is usually credited with the idea and why? How similar or different were their
theories?
Twitomite Table – Answer key
The Journals of Charlotte Durand, Explorer
Twitomite Table
DIRECTIONS-As you read the journals and look at the sketches, fill in this chart to get a better picture of twitomite diversity.
Shovel-nosed
Twitomite
Saw-Toothed
Twitomite
Long-Tongued
Twitomite
Vampire Twitomite
Big-Jawed
Twitomite
Long-Toothed
Twitomite
Green Twitomite
Marine Twitomite
Snout
Island Habitat
Food source
Outstanding Trait
Shovel shaped
Sandy Island
Beach
Insects and sea
creatures
Shovel-shaped
snout
How does this trait help it to
survive?
The shovel-shaped snout allows it
to easily dig through the sand and
eat insects and sea creatures
Twitomites – What do you think?
1. How many species of twitomites were there 20,000 years ago? Were the individual twitomites
genetically identical? Explain.
2. When did the twitomites first become separated into three distinct populations! Do you think the
twitomite populations on the three islands were fairly similar or radically different at first?
3. Over time] what could have caused different species of twitomites to arise on each of the three
islands? Be specific.
4. What had happened to the islands by the time the explorers arrived? How did this affect the
twitomites?
5. Explain how each of the eight twitomites is particularly well adapted to its habitat.
6. Some scientists think about the process of speciation in terms of this formula:
isolation + time + evolution = SPECIATION
Apply this formula to twitomites to explain how their single ancestor evolved into eight different species.
Twitomite time line