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Bell Bell
Ringer
Ringer – 10/01
1.What is the best indicator that
two organisms are the same
species?
Learning Target: We will describe how speciation occurs.
Closure task: I can determine which isolation method is
causing a particular species to speciate.
Agenda
Bell Ringer
1.What is a
species
2.Speciation
3.Dichotomous
Key
BIOLOGICAL SPECIES CONCEPT
Species: a species as a population or group of
populations whose members have the potential
to interbreed in nature and produce viable, fertile
offspring
WHAT HAPPENS WHEN YOU MATE TWO
DIFFERENT SPECIES?
Similarity between different species. The
eastern meadowlark (Sturnella magna, left)
and the western meadowlark (Sturnella
neglecta, right) have similar body shapes and
colorations. Nevertheless, they are distinct
biological species because their songs and
other behaviors are different enough to
prevent interbreeding should they meet in the
wild.
What if I find a new
species of Sturnella?
Diversity within a species. As diverse as we
may be in appearance, all humans belong to
a single biological species (Homo sapiens),
defined by our capacity to interbreed.
SPECIATION
New species occur due to reproductive isolation!
This can because of:
Geographic Isolation: Species live in different habitats
Temporal isolation: Species breed at different times.
Behavioral isolation: Species engage in distinct
courtship and mating rituals
Mechanical isolation: Interbreeding is prevented by
structural or molecular blockage (physically can’t
mate!)
Geographical Isolation
The separation of two populations of the same
species or breeding group by a physical barrier
Temporal Isolation
Mechanism that prevents species from
mating because they breed at different
times.
Northern Red-legged frog
Foothill Yellow-legged frog
Western spotted skunk
• Mates late summer
Eastern spotted skunk
• Mates late winter
Behavioral isolation:
Species engage in
distinct courtship
and mating rituals
Birds of paradise:
• https://www.youtube.com
/watch?v=nS1tEnfkk6M
Bowerbird:
• https://www.youtube.com
/watch?v=wCzZj21Gs4U
Mechanical isolation:
Interbreeding is prevented by structural
or molecular blockage (physically can’t
mate!)
HOW TO USE A DICHOTOMOUS KEY (ALIEN
WORKSHEET) MUST CLASSIFY 10 ALIENS
1. Look at only one creature (picture) at a time
2. Read statements 1a and 1b on the back. Decide
which statement is true.
3. Then follow the directions after that step (go to
direction 2 or go to direction 11)
4. Each step of directions will have two new statements.
Decide which statement is true and that will lead you
to new directions.
5. Follow the directions until you reach a Genus species.
6. Choose a new creature and start at directions 1
again.
ExitBellSlip
Ringer
1. Suppose a river cut across a population of frogs,
preventing the two groups from interbreeding. What
type of isolating mechanism is this?
2. Suppose a group of frogs choose their mates based on
their mating call. Different frogs having different mating
calls that attract different mates. What type of isolating
mechanism is this?
How did you do? Rate yourself!
We will classify organisms into taxonomic levels based on characteristics.
I can list the taxonomic levels and determine evolutionary relationships
based on taxonomic.