1. SPECIATION Ch. 16-3 pp. 326-330 Warm up 2/25:
Define: Homologous Structures, Analogous Structures and Vestigial Organs/Structures.
Give 1 example of each
What is the main difference between a homologous structures and vestigial Structures.
SPECIATION
Ch pp

2. Forming a new species Speciation: forming a new species
Species: a group of organisms that can mate and produce fertile offspring
1. same number of chromosomes
2. similar morphology (body
structure)

3. Species Types
Morphological Species – Defined using similar characteristics.
Biological Species – A species can reproduce and have fertile offspring.
A group of organism that can successfully interbreed.
Cannot breed fertile offspring with other species.

4. Disruptive Selection
Divergent evolution that most likely results in two new species

5. Mechanisms
Allopatric speciation caused by geographic isolation (physical separation of organisms)

6. Mechanisms Cont.
Sympatric Speciation due to reproductive isolation (barriers to successful breeding)
Prezygotic: before fertilization (i.e breeding times or home range)
Postzygotic: after fertilization- infertile
offspring (chromosome # doesn’t add up)
Liger – Tiger and Lion produce an infertile offspring

7. Rates of Speciation Gradualism: slow divergence
Punctuated equilibrium: sudden shift in form (irregular)

8. Homework: Tri-fold Vocab Due Tuesday 2/26
Genetic Drift
Biological Species Concept
Allopatric Speciation
Sympatric Speciation
Prezygotic Isolation
Postzygotic Isolation
Gradualism
Punctuated Equilibrium
Speciation
Homework: Due Wednesday 2/27
Read p Do p 330 # 1-7
Study Guide & Raft Due Thursday
Exam Friday: Intervention this week.