Class notes
BIOB51: Evolutionary Biology - Lectures 2 & 3 Review
BIOB51: Evolutionary Biology - Lectures 2 & 3 Review with Questions
[Show more]
Connected book
Book Title:
Author(s):
- Edition:
- ISBN:
- Edition:
Seller
Follow
Content preview
LECTURE 2 TOPICS❖ Why is it often difficult to conceptualize biological evolution?
➢ Mechanisms within evolution are challenging to describe
➢ There are issues with scale and the concept of time
➢ Difficulty demonstrating and observing “evolution” in a teaching lab
❖ What is the difference between a theory and a fact?
➢ Misconception → “Evolution is not a theory, it's not a FACT”
■ “Fact” → information that can be used as evidence
■ Theory → well-established, well-supported, well-documented explanation
for our observations and is supported by facts
➢ A theory is an explanation of facts
❖ What is the relationship between theory and law?
➢ Law → a description
➢ Theory → explains the WHY
■ E.g. Law of gravity is a description and it does not explain the why,
whereas Newton's Theory of Gravity, Einstein’s Theory of Relativity
explains the WHY (theory)
➢ Evolution → also is something that is true,
observable and testable
■ E.g Speciation is a description
(law): when a group within a species
separates from other members of its
species (common ancestor) and
develops its own unique
characteristics
● A theory then will explain
this law → as to WHY
speciation occurs
❖ Why is it essential that we have a grasp on the concept of time, in an
evolutionary sense?
➢ Scale and the concept of time
■ Several million years may seem like a long time to us BUT in
evolutionary terms, it is considered recent because even after
several million years of divergence, our DNA is still 99%
identical
, ➢ Demonstrating Evolution
■ Showing the effect of light on plants is something that can
be done in the lab even now → Anywhere in the world
■ Proving that DNA is the heritable material in our body is
also something that can be demonstrated in a lab setting
➢ BUT, You can’t “do” evolution again
■ You can’t demonstrate evolution
■ How do you show that a whale evolved from a
camel
➢ All of this “stuff” (change) didn't happen overnight → took a very very long time
■ Biological evolution → is a process by which populations of organism
change over time
❖ How does an understanding of evolution inform us about all aspects of life and the
interconnectivity of life?
➢ Every organism that lives today on Earth are all a PRODUCT of evolution
■ By understanding evolution, we can understand
● WHY is the natural world the way it is today?
● The similarities and differences among and between species
● The geographical distribution of species
● The adaptation and weaknesses of living things
➢ Studying evolution can help us in many ways (E.g.)
■ Finding new ways to fight off deadly viruses and bacteria that make us
sick
■ Allows us to have a better understanding of how insects become resistant
to pesticides
■ We can understand the consequences of human impact on the planet
● Pollution
● Climate change
● Invasive species
■ We can compare today's extinctions to the past → which can help us
predict and think about new strategies to combat the current wave of
extinctions
,❖ Why do we know that whales are mammals? We discussed several features and
examples.
➢ Whales share many synapomorphies with mammals
■ Synapomorphies → derived form of a trait that is shared by a group of
related species, a trait that evolved in the immediate common ancestor of
the group and was inherited by ALL its descendants
● E.g Synapomorphies in whales and mammals
◆ Mammary glands
◆ Three middle ear bones
◆ Hair (in developing embryos)
❖ What is Pakicetus and how does it fit within the phylogeny of
cetaceans?
➢ Pakicetus (“whale of Pakistan”) → ancestors of whales
■ Was the first terrestrial cetacean (Latin: “large sea
creature” - collective noun used to describe all 90
species of whale, dolphins and porpoises) ever
discovered
■ Fossils showed → a whale that spent at least some time on land
➢ Pakicetus shared similarities with modern relative (E.g dolphins and whales)
Dorudon: they show strong resemblance to
teeth of some extinct land mammals
(pakicetus)
, Pakicitus had cetaceans synapomorphies
● Fragments of skull revealed Pakicetus
to have cetacean-like involucrum
(thick lip of dense bone that forms the
inner wall of the ectotympanic found
in mammals)
● Bone found in the ear: Both have the
same bone structure links the
Pakicetus to the dolphin
Talus = Astragalus → “ankle bone” →
synapomorphy
Shape of the astragalus bone is more
important in this case:
● The bone is more similar to the bone
of ungulates (having hoofs and
specifically even-toed).
●
● Thus revealing that the pakicetus
could have been more closely
connected to ungulates rather than
canines
● Transitional fossils reveal that
pakicetus are linked to land
mammals
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through credit card or Stuvia-credit for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying these notes from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller emerald1. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for CA$12.23. You're not tied to anything after your purchase.
Can Stuvia be trusted?
4.6 stars on Google & Trustpilot (+1000 reviews)
72042 documents were sold in the last 30 days
Founded in 2010, the go-to place to buy study notes for 14 years now