The Origin of Species

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6

Depending on the species in question, speciation might require the change of only a single allele or many alleles.

From Speciation to Macroevolution:

Macroevolution is the cumulative effect of many speciation and extinction events.

Slide 36

Speciation Review

Original population

Allopatric speciation

Sympatric speciation

Slide 37

Speciation

Ancestral species:

Triticum

monococcum

(2n = 14)

AA

BB

Wild

Triticum

(2n = 14)

Product:

AA BB DD

T. aestivum

(bread wheat)

(2n = 42)

Wild

T. tauschii

(2n = 14)

DD

Slide 38

You should now be able to:

Define and discuss the limitations of the four species concepts.

Describe and provide examples of prezygotic and postzygotic reproductive barriers.

Distinguish between and provide examples of allopatric and sympatric speciation.

Explain how polyploidy can cause reproductive isolation.

Define the term hybrid zone and describe three outcomes for hybrid zones over time.