Post on 02-Jan-2016
Chapter 24The Origin of Species
Microevolution (you will remember from chapter 23) is …
Chapter 24The Origin of Species
Microevolution (you will remember from chapter 23) is the generation-to-generation change in allele frequencies within a species
Chapter 24The Origin of Species
Microevolution (you will remember from chapter 23) is the generation-to-generation change in allele frequencies within a species.
Macroevolution (on the other hand) is the origin of new species.
Chapter 24The Origin of Species
Macroevolution happens two ways:
Chapter 24The Origin of Species
Macroevolution happens two ways:
Anagenesis – linear evolution
Cladagenesis – branching evolution
Chapter 24The Origin of Species
Macroevolution happens two ways:
Anagenesis – linear evolution
Cladagenesis – branching evolution
Chapter 24The Origin of Species
Macroevolution happens two ways:
Anagenesis – linear evolution
Cladagenesis – branching evolution
Chapter 24The Origin of Species
What is a species?
Chapter 24The Origin of Species
What is a species?Reproductive isolation based on prezygotic and postzygotic barriers.
Chapter 24The Origin of Species
•Habitats
•Mating behaviors
•Mating seasons
•Mechanical incompatibility
•Gamete incompatibility.
Chapter 24The Origin of Species
Prezygotic barriers:
•Embryo is inviable
•Offspring do not survive to adulthood
•Offspring are infertile.
Chapter 24The Origin of Species
Postzygotic barriers:
Species concept does not apply to:
Chapter 24The Origin of Species
Species concept does not apply to:•Fossils
•Asexual reproduction.
Chapter 24The Origin of Species
Other proposed definitions of species:
Chapter 24The Origin of Species
Other proposed definitions of species:•Ecological
•Morphological
•Pluralistic
•Genealogical.
Chapter 24The Origin of Species
SpeciationAllopatric –
Sympatric –
Chapter 24The Origin of Species
SpeciationAllopatric – Geographic barriers divide a population
Sympatric –
Chapter 24The Origin of Species
SpeciationAllopatric – Geographic barriers divide a population
Sympatric – New species develop in the midst of parent species.
Chapter 24The Origin of Species
Causes of sympatric speciation:
Chapter 24The Origin of Species
Causes of sympatric speciation:
•Polyploidy (mostly in plants)
•Host switching (in parasites)
•Nonrandom mating (in polymorphic populations).
Chapter 24The Origin of Species
Punctuated equilibriumSpecies change quickly as they bud off from parent species, then change relatively little for the rest of their existence.
Chapter 24The Origin of Species
Evolutionary Novelties
Chapter 24The Origin of Species
Evolutionary Novelties•Modifications of older structures
Chapter 24The Origin of Species
Evolutionary Novelties•Modifications of older structures
•Functions may change or may stay the same.
Chapter 24The Origin of Species
“Evo-Devo”
Chapter 24The Origin of Species
“Evo-Devo”Genes that control development play a major role in evolution.
Chapter 24The Origin of Species
“Evo-Devo”
Chapter 24The Origin of Species
“Evo-Devo”
Chapter 24The Origin of Species
A trend is not a goal.
Chapter 24The Origin of Species
Evolution is not goal oriented.
A trend is not a goal.
Chapter 24The Origin of Species
Evolution is not goal oriented.
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