4th Class – Chapter 5 – Macroevolution processes of
Vertebrate and Mammalian Evolution.
I unfortunately missed this class because of the season’s
allergies that were attacking me that week, but I did read the chapter and I
will do an explanation based on the chapter.
It is important to understand that due to the large amount
of living organisms, biology classifies categories based on their physical
similarities. But biology also have to consider their evolutionary descendent.
If a structure is shared by the same species taking in consideration they are
descendants from a same ancestor, the structure is called homologies and that indicated an evolutionary relationship. If the
similarities shared are from different ancestors the structure is called analogies and the processes that lead
to the development of these analogies is called homoplasy.
To interpret evolutionary relationships, biologists use two
schools. The first one being: Evolutionary
systematics that is the more
traditional and Cladistics, they
both share plenty of similarities, they both recognize that organisms should be
compared using similar features, that some features are more informative than
others, and they are both interested in tracing evolutionary relationships. But
they do have some differences, for example the Cladistics is more explicit and
rigorous when defining the kings of homologies that yield most useful
information.
Despite of which approach, most biologist use biological species concepts to compare
organisms. To understand what they are, it is important to understand first how
they came about not forgetting the fact
that new species are usually created when present in an isolate condition.
Considering different types of variation of organisms, an
organism that is multicellular and moves around is considered an animal. The
vertebrates fall under the chordate phyla, which mean they are animals with a
nerve cord.
The vertebrates receive this name because they have a
vertebral column. They also have a developed brain and paired sensory
structures. Vertebrates are divided into:
Cartilaginous fish
Bony Fish
Amphibians
Reptiles
Birds
Mammals
Personal Input
Missing this class was hard for me just because I feel like
the book is very complicated at times, so I had to read several times the same
parts to get an overall understanding of what the subject was.
It is really interesting to know biologists take the time to
study the evolution of a certain organism that lived millions of years ago, just
to be able to separate into groups current species.
I understand this subject was important to understand the
classification of primates coming up in the next chapter.
Additional Information
For my additional information I decided to add some
information on the differences between the Evolutionary
systematics and the Cladistics:
This first link is a good explanation of the Cladistics. It
gives an introduction, methodology, implications and what is the need for them:
This next link is in the same website, but it explains the
evolutionary systematics, it presents graphics and presentations on the
subject.
