Speciation mechanisms A species is Speciation is the

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Speciation mechanisms • A species is… • Speciation is… • …the evolution of reproductive

Speciation mechanisms • A species is… • Speciation is… • …the evolution of reproductive isolation between once-interbreeding populations • How does reproductive isolation evolve? • In most situations, speciation requires geographic isolation of once-interbreeding populations

Speciation mechanisms • Speciation results in the evolution of two or more “descendant” species

Speciation mechanisms • Speciation results in the evolution of two or more “descendant” species from a single “ancestral” species • transmutation of species, cladogenesis

Speciation mechanisms • Continental allopatric speciation…

Speciation mechanisms • Continental allopatric speciation…

continental allopatric speciation Species A

continental allopatric speciation Species A

continental allopatric speciation Population A''

continental allopatric speciation Population A''

continental allopatric speciation Species A no speciation

continental allopatric speciation Species A no speciation

continental allopatric speciation Population A''

continental allopatric speciation Population A''

continental allopatric speciation Species B Species C complete speciation

continental allopatric speciation Species B Species C complete speciation

continental allopatric speciation Population A''

continental allopatric speciation Population A''

continental allopatric speciation Species A'' “incipient speciation”

continental allopatric speciation Species A'' “incipient speciation”

continental allopatric speciation Species A'' “incipient speciation” How will natural selection act in this

continental allopatric speciation Species A'' “incipient speciation” How will natural selection act in this situation?

continental allopatric speciation Species A'' “incipient speciation” reinforcement

continental allopatric speciation Species A'' “incipient speciation” reinforcement

continental allopatric speciation Species B Species C “incipient speciation” reinforcement

continental allopatric speciation Species B Species C “incipient speciation” reinforcement

continental allopatric speciation

continental allopatric speciation

continental allopatric speciation

continental allopatric speciation

continental allopatric speciation meadowlark narrow-mouth toad kingbird diamondback rattlesnake ribbon snake monarch butterfly scrub

continental allopatric speciation meadowlark narrow-mouth toad kingbird diamondback rattlesnake ribbon snake monarch butterfly scrub jay Species B Species C

Speciation mechanisms "Adaptive Radiation" evolutionary time derived, descendant species “speciation events” ancestral species phenotypic

Speciation mechanisms "Adaptive Radiation" evolutionary time derived, descendant species “speciation events” ancestral species phenotypic divergence

Speciation mechanisms

Speciation mechanisms

Speciation mechanisms

Speciation mechanisms

Speciation mechanisms

Speciation mechanisms

The Galapagos Islands

The Galapagos Islands

The Galapagos Islands

The Galapagos Islands

island allopatric speciation

island allopatric speciation

island allopatric speciation OCEAN Hawaiian

island allopatric speciation OCEAN Hawaiian

island allopatric speciation

island allopatric speciation

island allopatric speciation OCEAN Hawaiian B A

island allopatric speciation OCEAN Hawaiian B A

island allopatric speciation OCEAN Hawaiian B A

island allopatric speciation OCEAN Hawaiian B A

island allopatric speciation OCEAN B' Hawaiian A' B A

island allopatric speciation OCEAN B' Hawaiian A' B A

island allopatric speciation OCEAN B' Hawaiian A' B A

island allopatric speciation OCEAN B' Hawaiian A' B A

island allopatric speciation B''' B" A" B' Hawaiian OCEAN A' B A

island allopatric speciation B''' B" A" B' Hawaiian OCEAN A' B A

island allopatric speciation

island allopatric speciation

allopolyploid speciation Species A 2 N = 6 Species B 2 N = 4

allopolyploid speciation Species A 2 N = 6 Species B 2 N = 4

allopolyploid speciation meiosis Species A 2 N = 6 meiosis Species B 2 N

allopolyploid speciation meiosis Species A 2 N = 6 meiosis Species B 2 N = 4

allopolyploid speciation meiosis A gametes N=3 Species A 2 N = 6 meiosis Species

allopolyploid speciation meiosis A gametes N=3 Species A 2 N = 6 meiosis Species B 2 N = 4 B gametes N=2

allopolyploid speciation meiosis hybridization A gametes N=3 Species A 2 N = 6 allopolyploid

allopolyploid speciation meiosis hybridization A gametes N=3 Species A 2 N = 6 allopolyploid hybrid zygote N = 5 (haploid) meiosis Species B 2 N = 4 B gametes N=2

allopolyploid speciation mitosis vegetative reproduction division replication allopolyploid hybrid individual N = 5 (haploid)

allopolyploid speciation mitosis vegetative reproduction division replication allopolyploid hybrid individual N = 5 (haploid)

allopolyploid speciation mitosis vegetative reproduction allopolyploid hybrid individual N = 5 (haploid)

allopolyploid speciation mitosis vegetative reproduction allopolyploid hybrid individual N = 5 (haploid)

allopolyploid speciation allopolyploid hybrid individual N = 5 (haploid)

allopolyploid speciation allopolyploid hybrid individual N = 5 (haploid)

allopolyploid speciation allopolyploid hybrid individual N = 5 (haploid)

allopolyploid speciation allopolyploid hybrid individual N = 5 (haploid)

allopolyploid speciation replication followed by nondisjunction during mitosis allopolyploid hybrid individual N = 5

allopolyploid speciation replication followed by nondisjunction during mitosis allopolyploid hybrid individual N = 5 (haploid) allopolyploid hybrid individual 2 N = 10 (diploid)

allopolyploid speciation mitosis vegetative reproduction allopolyploid hybrid individual N = 5 (haploid) allopolyploid hybrid

allopolyploid speciation mitosis vegetative reproduction allopolyploid hybrid individual N = 5 (haploid) allopolyploid hybrid individual 2 N = 10 (diploid)

allopolyploid speciation allopolyploid hybrid individual N = 5 (haploid) allopolyploid hybrid individual 2 N

allopolyploid speciation allopolyploid hybrid individual N = 5 (haploid) allopolyploid hybrid individual 2 N = 10 (diploid)

allopolyploid speciation allopolyploid hybrid individual N=5 mitosis vegetative reproduction allopolyploid hybrid individual 2 N

allopolyploid speciation allopolyploid hybrid individual N=5 mitosis vegetative reproduction allopolyploid hybrid individual 2 N = 10 (diploid)

allopolyploid speciation meiosis allopolyploid hybrid individual N = 5 (haploid) allopolyploid hybrid individual 2

allopolyploid speciation meiosis allopolyploid hybrid individual N = 5 (haploid) allopolyploid hybrid individual 2 N = 10 (diploid)

allopolyploid speciation hybrid individual can reproduce sexually

allopolyploid speciation hybrid individual can reproduce sexually