Video Transcript
The diagram provided shows an
incomplete evolutionary tree of existing primates belonging to the Hominoidea
superfamily. How many different species are
shown?
Let’s start by reviewing taxonomy,
which is the study of biological classification. We commonly use seven main
taxonomic categories: kingdom, phylum, class, order, family, genus, and species. The relationships between these
different taxonomic groups are illustrated in this diagram on the right.
The largest group displayed here is
the kingdom. Within each kingdom are multiple
phyla. Within each phylum are multiple
classes. Within each class are multiple
orders. Within each order are multiple
families. Within each family are multiple
genera. And finally, within each genus are
multiple species, which is the smallest taxonomic rank consisting of individual
organisms that can reproduce with each other to create fertile offspring.
It’s important to note that we can
create extra categories between these groupings as we require them, which is why the
question mentions a superfamily. This is an extra category that has
been placed above family to help organize primate taxonomy.
We often use an evolutionary tree
to help us visualize evolutionary relationships. On the left of the screen, you can
see an example of one provided by the question that outlines existing primate
taxonomy. The ends of the branches on the far
right of the evolutionary tree, which have been underlined in pink, show modern-day
species, including our own species, Homo sapiens. Each of the orange circles where
these branches connect illustrates the most recent common ancestor between these
modern species. The ancestral species evolved over
time into the species that exist today, listed on the far right of the evolutionary
tree.
The question is asking us how many
different species are shown in this evolutionary tree. To work this out, let’s count the
number of existing species, which you’ll recall are those that have been underlined
in pink. Now we know the correct answer to
this question. The evolutionary tree displays nine
species.
