Textbook Notes (378,542)
CA (167,160)
UTSC (19,214)
Anthropology (538)
ANTB14H3 (34)
Chapter 4

Chapter 4

2 Pages
119 Views

Department
Anthropology
Course Code
ANTB14H3
Professor
Michael Schillaci

This preview shows half of the first page. Sign up to view the full 2 pages of the document.
Week 3
Chapter 4: Speciation and Phylogeny
Microevolution: how populations change under the influence of natural selection and other
evolutionary forces
oNatural selection, mutation, genetic drift
oAffect morphology, physiology, behaviour of particular species in particular environments
Macroevolution: how species and higher taxa are created
oTells how new species, genera, families, higher groupings come into existence
Species can usually be distinguished by their behaviour and morphology
Most zoologists believe in biological species concept: defines a biological species as a group of
organisms that interbreed in mature and are reproductively isolated
Reproductive isolation: members of a given group of organisms do not mate successfully with
organisms
Biological species concept defines a species in terms of ability to interbreed because successful
mating leads to gene flow
Gene flow: the movement of genetic material within parts of a population or from one population to
another
oTends to maintain similarities among members of same species
Reproductive isolation prevents species from genetically blending
Ecological species concept emphasizes the role of selection in maintaining species boundaries
Allopatric speciation: when population divided by some type of barrier and different parts of
population adapt to different environments
If there is some gene flow after the members of 2 populations initially come back into contact, 2
additional processes may increase degree of reproductive isolation and facilitate the formation of
new species
oCharacter displacement: occur if competition over food, mates or other resources increases
the morphological differences between the immigrants and the residents
oReinforcement: may act to reduce the extent of gene flow between the populations
Allopatric speciation requires a physical barrier that initially isolates part of population,
interrupts gene flow, allows isolated subpopulation to diverge from original population under
influence of natural selection
New species may also form if there is strong selection that favours two different phenotypes
Gene flows welds species together, species can be split only if gene flow is interrupted
Selection can lead to speciation even when there is interbreeding
oWeak version of hypothesis: parapatric speciation: selection alone is not sufficient to
produce a new species, but new species can be formed if selection is combined with partial
genetic isolation
At habitat boundaries, animals that come from different habitats and have different
characteristics may mate and create hybrid zone
oStrong version: sympatric speciation: strong selection favouring different phenotypes can
lead to speciation even where there is no geographic separation, therefore initially there is
extensive gene flow among individuals in population
Adaptive radiation: when a single kind of animal or plant diversifies to fill many available niches
Phylogenetic reconstruction plays 3 important roles in study of organic evolution:
oPhylogeny is basis for identification and classification of organisms
oKnowing phylogenetic relationships often helps explain why a species evolved certain
adaptation and not others
oWe can deduce function of morphological features or behaviours by comparing the traits of
different species called comparative method
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
Week 3 Chapter 4: Speciation and Phylogeny Microevolution: how populations change under the influence of natural selection and other evolutionary forces o Natural selection, mutation, genetic drift o Affect morphology, physiology, behaviour of particular species in particular environments Macroevolution: how species and higher taxa are created o Tells how new species, genera, families, higher groupings come into existence Species can usually be distinguished by their behaviour and morphology Most zoologists believe in biological species concept: defines a biological species as a group of organisms that interbreed in mature and are reproductively isolated Reproductive isolation: members of a given group of organisms do not mate successfully with organisms Biological species concept defines a species in terms of ability to interbreed because successful mating leads to gene flow Gene flow: the movement of genetic material within parts of a population or from one population to another o Tends to maintain similarities among members of same species Reproductive isolation prevents species from genetically blending Ecological species concept emphasizes the role of selection in maintaining species boundaries Allopatric speciation: when population divided by some type of barrier and different parts of population adapt to different environments If there is some gene flow after the members of 2 populations initially come back into contact, 2 additional processes may increase degree of reproductive isolation and facilitate the formation of new species o Character displacement: occur if competition over food, mates or other resources increases the morphological differences between the immigrants and the residents
More Less
Unlock Document


Only half of the first page 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