THE ORIGIN OF NEW SPECIES

Speciation

Lesson #20

STAGES IN THE FORMATIONOF A NEW SPECIES

1. Production of evolutionary changes in populations

2. Genetic isolation of the new population

3. Gradual differentiation

4. Speciation

GENETIC ISOLATION OF THE NEW POPULATION

1. Allopatricspeciation:

a. Geographical barriers

2. Sympatricspeciation: Speciation withinthe samegeographical area.

a) Sexual barriers

b) Physiologicalbarriers

c) Chromosomalbarriers

d) Ethological barriers: (behavioral)

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PROCESSES OF EVOLUTION: SPECIATION

Microevolution

The process of evolutionthat causes the appearanceof new species.

Species belonging to thesame genus were causedby microevolution.

PROCESSES OF EVOLUTION: SPECIATION

Macroevolution

The type of evolution thatresulted in large groups of different species because of drastic changes.

Example: Birds and mammals evolving fromreptiles.

Darwin supported this type of evolution worked in the samemanner, but over longer periodsof time under more intense situations.

Palaeontological studies indicateotherwise. A quick process.