Class Notes (836,840)
Canada (509,920)
Biology (2,229)
BIO120H1 (1,171)
Lecture 20

Lecture 20

3 Pages
81 Views
Unlock Document

Department
Biology
Course
BIO120H1
Professor
James Thomson
Semester
Fall

Description
Lecture 20 Two main species concept - Taxonomic or morphological o Based primarly on distinct morphological differences o What the things look like o Commonly used o Can be arbitrary though o Collect species and identify gaps in phenotypic variation o Criticized by geneticists, because different people will come up with different numbers - Biological o Based on inter-fertility among individuals o A lot of organisms that you cannot cross o Have info only about those that we can o What about organisms that do not have sex, like bacteria o Found by Ernst Mayr – Harvard 1904-2005  A group od interbreeding natural populations that are reproductively o First idea was suggested by Dobzhansky Two main modes of speciation - Allopatric o Apart o Start with a population that gets split, geographical barrier that limits gene flow, evolution and genetic differentiation occurs; if they do come back together they cant interbreed o Geographical - Sympatric o Should be gene flow going on that stops diversion o Hardly occurs o Controversy: how you can differentiate it from allopatric? o Sympatric speciation occurs in plants, but rare in animals RI –reproductive isolation - Finding a compatible mate - Mating & fertilization - Development of zygote - Adult growth & survival - Reproduction & RI mechnisms - premating isolation o geography is different, or different habitats(ecology) o temporal, not the same time for mating; behavioral, female don’t choose you o mechanical, things just dont fit; prevention of fertilization occurs o apple maggot flies: habitat and temporal isolation; native to north America; use horthons as a host; population that subdivided in teo groups to different food resources; 6% matings between each other; example of sympatric speciation o Shemske; monkey flower: pollinator preferences & altitude; in the wild don’t mate together, but if you breed them by yourself they can mate - postmating isolation o individuals mate together but preventing the proper functioning of zygotes once they are formed o inviability, sterility, or abnormal
More Less

Related notes for BIO120H1

Log In


OR

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