1. 1.C.1: Speciation and Extinction
JULIAN ANDERSON

2. Learning Objectives Learning Objectives:
LO 1.20 the student is able to analyze data related to questions of speciation and extinction throughout the Earth’s History
See SP 5.1
LO 1.21 the student is able to design a plan for collecting data to investigate the scientific claim that speciation and extinction have occurred throughout the Earth’s history
See sp4.2

3. Speciation
Definition: lineage-splitting event that produces two or more separate species
Speciation rates can vary, especially when adaptive radiation occurs when new habitats become available

5. Causes of Speciation Geographic isolation Rivers change course
Mountains rise
Continents drift
Organisms migrate

6. Causes of Speciation Reproductive isolation
Evolution of different mating location, time, or rituals
Lack of fit between sexual organs
Offspring unviability or sterility

9. Modes of Speciation Allopatric Peripatric Parapatric
Allo = other, patric = place
Geographically isolated populations
Peripatric
Peri = near, patric = place
A small population isolated at the edge of a larger population
Parapatric
Para = beside, patric = place
A continuously distributed population

11. Modes of Speciation Sympatric Sym = same, patric = place
Within the range of the ancestral population

14. Extinction
Definition: the cessation of existence of a species or group of taxa, reducing biodiversity
Species extinction rates are rapid at times of ecological stress
5 major extinctions

18. Causes of Extinction Competition Sudden unprecedented event
Habitat loss
Fires
Disease

20. The 5 Extinctions Permian Extinction Ordovician-Silurian Extinction
266 million to 252 million years ago
95% of marine species wiped out
70% of land species
Ordovician-Silurian Extinction
444 million years ago
25% of marine families
85% of marine species

22. The 5 Extinctions
Cretaceous-Tertiary (K-T)/Cretaceous-Paleogene (K-Pg) Extinction
66 million years ago
80% of all animal species
End-Triassic Extinction
201 million years ago
Caused by rapid climate change or asteroid striking earth
20% marine families
76% of all species

24. The 5 Extinctions Devonian Extinctions
407 million to 359 million years ago
15-20% of marine families
70-80% of animal species

25. Further Reading
life/a/species-speciation