2. The Story...
Toby was a young adventurous Joey who lived
in the Australian outback with his Mum, Dad
and three sisters. Toby loved hearing stories
was interested in hearing more about his
heritage. He became interested in developing
his understanding of how Kangaroos have
evolved over time and where they came from.
Toby
3. Toby’s parents were not able to tell him much except
that their family had been living in Alice Springs for the
past 100 years. This did not satisfy Tody’s intrigue and
so he set out determined to find some more answers.
Joey had no idea of where to begin his investigation
but knew that his teachers at school always had
answers. So his first stop was to visit his favourite
teacher at school Mr Amos. Mr Amos was Toby’s
science teacher and Joey recalled learning about
ancestry the previous term. Toby thought that Mr
Amos must be able to help him out somehow! Off Joey
went in search of Mr Amos and hopefully some
answers!
Mr Amos
4. Hi Toby. To what
do I owe this
Hi Mr Amos! pleasure of have
you visit me on
your day off?”
5. Well Mr Amos I’m trying Well Joey I’m very
to research my ancestry impressed that you are so
and figure out where they interested in your ancestry.
came from but I need Do you remember what we
your help because I don’t talked about last term
know where to start!” when we were learning
about ancestry.
6. Do I ever Mr Amos. We
learnt about how species
evolve and
palaeontologists who Very good Joey. I’m very
look at comparative impressed with how much
anatomy to figure out you remember.”
major lineages of species.
7. Thank you Mr Amos but Well Joey it just so happens
how will this help me that a close friend of
figure out my ancestry?” mine, Samantha, is a
palaeontologist who I’m
sure would be more than
happy to have a look into
your ancestry with you.
8. Gees Mr Amos that would
be fantastic! Thank-you!
No worries Joey. I’m glad I
could help. Good luck in
your quest for
information!”
9. So off Toby went to meet Samantha. He was
very excited about this as the prospect of
finally learning something about his ancestry
was in close reach!
10. Samantha greeted Toby with open arms. She was
very excited to see him as Mr Amos had called
ahead and informed her that Toby was on his way
over. Samantha loved visitors and embraced any
opportunity she had to talk about her love and
passion of palaeontology. Samantha had a
particular interest in the area of comparative
anatomy and so was very keen to look into Toby’s
ancestry and determine how comparative
anatomy has played a part in the evolution of
Toby’s family.
Samantha
11. Why hello young Toby! I’m very
excited that you have come to Sounds good Samantha.
visit me and that you have I’m very interested to
taken an interest in my work. learn about anything to
Let’s start by providing you with do with ancestry.
some background information
about comparative anatomy so
you know how and why its used.
12. 1. Alright lets get started! 2. It is assumed that groups
Comparative anatomy is about with little in common have Wow like how its
establishing relationships on the diverged from a common believed that tree
basis of structural similarities and ancestor much earlier in Kangaroos evolved from
differences. Palaeontologists geological history compared Possums because they
research comparative anatomy as a to groups that have a lot in both use their tails .
means of determining how closely common.
related species are.
3. Comparative anatomists
look for structures in species
which although may serve
different functions are
fundamentally similar, and
therefore suggests a common
origin. These are called
homologous structures.
13. That’s a perfect example Toby. Great work!
Comparative anatomists look at three Cool so they look at things
things when trying to determine whether like the shape of a kangaroos
or not two structures or homologous or tail and how this has evolved
not. These are their relative as well as the development
positions, gross morphology, studying the of the embryo to determine
shape and general appearance or form of how different structures may
an organism and histological have similarities.”
appearance, the appearance of the tissues
of the body of an organism.
14. Exactly right Toby. Your
showing a fantastic
Animals are said to evolve in two So this is like what they
understanding already!”
different ways. These are referred to as say has happened with
divergent and convergent evolution. our pouch. It evolved
Divergent evolution occurs when the from another species and
same species splits into two or more Kangaroos adapted it to
descendant species due to developing
enable survival in their
new characteristics to enable them to
survive in their new and differing
new environment.
habitats.
This means that species that were
once similar or related then
become more and more
dissimilar. The newly produced
organisms have certain features in
common with each other and
with the ancestral stock from
which they arose and this forms
the basis of what we call
homology.
15. 1. Exactly right. That’s a perfect
3. The other type of
example of divergent evolution
evolution, convergent , occurs when
Toby. We call the result of divergent
complete organisms (or their parts)
evolution adaptive radiation, the
come to resemble each other more
process whereby populations move
closely than their ancestors (or
into new environments and undergo
ancestral structures) did, as a result o
rapid evolution as they adapt to the
their sharing similar environments.
unexploited habitats.
2. Comparative anatomists
construct evolutionary trees which
illustrates adaptive radiation in
which branches represent separate
lines of descent from a common
ancestor. The more similar two
organisms are, the more recently
they are assumed to have diverged.
16. So like how both Kangaroos
The anatomical similarity and Wombats have both
between species is said not to evolved to have sharp claws
be caused by common ancestry for digging in Australia’s dry
but by the fact that structures climate. Their claws are an
that perform the same functions analogous structure. And an
are likely to resemble one example of convergent
another to a degree. These evolution would again be
structures are described as possums and tree kangaroos.
analogous.
17. Excellent! You’ve got a
really good Thanks Samantha! You
understanding now. I have been a great help!
think I have given you
enough information to
do a bit of your own
investigating! Good
luck!
