Textbook Notes (381,224)
CA (168,409)
UTSG (11,042)
BIO (604)
BIO120H1 (306)
Chapter 3

COYNE CH3

3 Pages
96 Views

Department
Biology
Course Code
BIO120H1
Professor
Jean Jiang Nash

This preview shows page 1. Sign up to view the full 3 pages of the document.
Chapter 3: Remnants: Vestiges, Embryos, and Bad Design
There are features (vestigial) and genes that were once useful.
Vestiges feature of species that was an adaptation in its ancestors but has lost
its usefulness or has been adapted for other uses. VESTIGIAL BECAUSE NO
LONGER PERFORMS FUNCTION FOR WHICH IT EVOLVED (not necessarily
that it has no function).
Example: ostrich wings not for flight but for balance, weaponry and mating. Flightless
birds descend from flying ancestors. Bones of wings same in both flying and flightless birds.
Why lose flight: Flight is metabolically expensive and wings easily injured. If lack of
predators on island or food abundant on ground, then makes sense to reserve energy.
Still visible because a) has other uses b) actually in the middle of transition
Also, eyes in burrowers and cave dwellers: mutations over time can just accumulate if they
neither harm nor help the animal.
Whales: have hind limbs. Humans: appendix (for digesting cellulose).
VESTIGIAL TRAITS ONLY MAKE SENSE IN THE LIGHT OF EVOLUTION. i.e. moving
ears and non-functional wings dont make sense if we were created like this
ATAVISMevolutionary throwback. Ancestral traits reappearing occasionally on
individuals (not in the whole species). Come from re-expression of genes that were
functional in ancestors but silenced by natural selection. They are dormant and can
sometimes be reawakened. Ex. Horses with extra toesused to have 5 toed ancestors.
ATAVISM IS PROOF OF REMNANTS OF ANCIENT GENES.
DEAD GENES Atavisms and vestigial traits show us that when a trait is no longer used
or is reduced, the genes that make it dont instantly disappear from the genome. Evolution
deactivates them but does not eradicate them. Therefore, VESTIGIAL GENES MUST
EXIST. If we were created, then no vestigial genes will exist. (pseudogene-gene that does
not function).
Ex. Human: GLO-enzyme to metabolize vitamin c. Primates, fruit bats and guinea pigs
have pseudo-GLO because of missing nucleotide. Also, sequence of gene in close relatives
similar (similar pseudo-gene in humans and chimps compared to orangutans; bats and
guinea pigs have totally different pseudo-GLO).
www.notesolution.com

Loved by over 2.2 million students

Over 90% improved by at least one letter grade.

Leah — University of Toronto

OneClass has been such a huge help in my studies at UofT especially since I am a transfer student. OneClass is the study buddy I never had before and definitely gives me the extra push to get from a B to an A!

Leah — University of Toronto
Saarim — University of Michigan

Balancing social life With academics can be difficult, that is why I'm so glad that OneClass is out there where I can find the top notes for all of my classes. Now I can be the all-star student I want to be.

Saarim — University of Michigan
Jenna — University of Wisconsin

As a college student living on a college budget, I love how easy it is to earn gift cards just by submitting my notes.

Jenna — University of Wisconsin
Anne — University of California

OneClass has allowed me to catch up with my most difficult course! #lifesaver

Anne — University of California
Description
Chapter 3: Remnants: Vestiges, Embryos, and Bad Design There are features (vestigial) and genes that were once useful. Vestiges feature of species that was an adaptation in its ancestors but has lost its usefulness or has been adapted for other uses. VESTIGIAL BECAUSE NO LONGER PERFORMS FUNCTION FOR WHICH IT EVOLVED (not necessarily that it has no function). Example: ostrich wings not for flight but for balance, weaponry and mating. Flightless birds descend from flying ancestors. Bones of wings same in both flying and flightless birds. Why lose flight: Flight is metabolically expensive and wings easily injured. If lack of predators on island or food abundant on ground, then makes sense to reserve energy. Still visible because a) has other uses b) actually in the middle of transition Also, eyes in burrowers and cave dwellers: mutations over time can just accumulate if they neither harm nor help the animal. Whales: have hind limbs. Humans: appendix (for digesting cellulose). VESTIGIAL TRAITS ONLY MAKE SENSE IN THE LIGHT OF EVOLUTION. i.e. moving ears and non-functional wings dont make sen
More Less
Unlock Document


Only page 1 are available for preview. Some parts have been intentionally blurred.

Unlock Document
You're Reading a Preview

Unlock to view full version

Unlock Document

Log In


OR

Don't have an account?

Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


OR

By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.


Submit