Transcript reproductive isolation

Abert’s Squirrel
Kiabab Squirrel
Species = population or group that interbreed
and produce fertile offspring
• formation of a new species is called
speciation
- interbreeding links members of
species genetically
- gene pool can split and cause the two
populations to no longer interbreed and
reproductive isolation occurs.
• reproductive isolation can create two
different species
• can develop in a variety of ways:
1. Behavioral isolation
2. Geographic isolation
3. Temporal isolation
• cannot interbreed due to differences in
courtship rituals or other behaviors
• habitats may overlap, but mating does not
occur between species
Ex. Eastern and Western meadowlarks use
different songs to attract mates
Eastern
Meadowlark
Western
Meadowlark
• populations separated by geographic barriers
(water, mountains, rivers)
• may limit some species and not others
• new population gene pools formed and N.S. and
genetic drift act on each new gene pool
Ex. Abert’s Squirrel and Kiabab Squirrel
• reproduction occurs at different times
when two or more species reproduce
Ex. Orchids pollinating at different times
• Species M migrates to
islands, survives, and
reproduces
• founder effect (allele
frequencies differ)
• Species A evolves
due to N.S., founder
effect, and geographic
isolation
• A few birds then
move to a different
island and become
isolated as well
• populations adapt to
local environment
over time
• N.S. causes two
distinct species to
form with different
phenotypes
• Differences in beak
size create
reproductive isolation
• Birds only mate with
birds with same beak
size
• competition occurs
between species in
drought season and the
birds that are most
different have higher
fitness
• combined processes of
geographic iso.,
behavioral iso., and
genetic change could
repeat across chain of
islands
Not a new species:
 Biology.com