Download 16.3 Speciation

Chapter 16 Section 3
The Process of Speciation
AZ State Science Standards S4C4PO1: Identify the following components of natural selection, which can
lead to speciation: potential for a species to increase its numbers; genetic variability and inheritance of
offspring due to mutation and recombination of genes; finite supply of resources required for life;
selection by the environment of those offspring better able to survive and produce offspring
S4C4PO2 Describe how the continuing operation of natural selection underlies a population’s ability to
adapt to changes in the environment and leads to biodiversity and the origin of new species
Objectives:
-Identify the condition necessary for a new species
to evolve
-Describe the process of speciation in the
Galapagos finches
• Evolution of Corvette
• List three adaptations that have occurred and
the pressures that may have caused these
changes
Speciation:
• Changes that lead to the formation of new
species
• SpeciesA group of organisms that breed with one
another and produce fertile offspring (progeny)…
which means they share a common gene pool
Isolating Mechanisms:
• In order for a species to evolve into a new
species, the gene pools of two populations
must become separated…they must become
reproductively isolated from one another
Isolating Mechanisms Con’t:
• Behavioral Isolation:
-Occurs when two populations are capable
of interbreeding but have differences in
courtship rituals or other reproductive
strategies
For example: eastern vs western and songs that
attract mates
Isolating Mechanisms Con’t:
• Geographic Isolation:
– Occurs when barriers such as rivers, mountains,
etc separate two populations
– For example: Albert and Kaibab Squirrels are
separated by the Grand Canyon
Isolating Mechanisms Con’t:
• Temporal Isolation:
• -Two or more species reproduce at different
times
For example: Three similar species of
orchid release pollen on different days, thus
they are unable to pollinate one another
Temporal Isolation
Darwin’s Finches
• Read pages 408-409
• What type of isolating mechanism was
important in the formation of Galapagos finch
species?