1.C.1: Speciation and Extinction JULIAN ANDERSON

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

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

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

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

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

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

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

Causes of Extinction Competition Sudden unprecedented event Habitat loss Fires Disease

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

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

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

Further Reading https://evolution.berkeley.edu/evolibrary/article/0_0_0/evo_42 https://evolution.berkeley.edu/evo101/VC1bAllopatric.shtml https://www.khanacademy.org/science/biology/her/tree-of- life/a/species-speciation https://www.sciencedaily.com/terms/extinction.htm https://www.sciencelearn.org.nz/resources/1188-extinction https://www.britannica.com/science/extinction-biology