Unit 7- Lesson 7 (Speciation)

Speciation
Unit2.Lesson7

1

Multiple Choice

RECALL: What is gene flow?

• Genes are ordered from best to worst on your chromosomes

• Exchange of genes between two populations

• When nature selects for the best adapted organisms

• When an individual has a mutation that changes it's phenotype

SPECIES
RECALL: What is a

species?

A species is a group of
organisms so similar to
one another that they
can interbreed and
produce fertile offspring

Domain
Kingdom
Phylum
Class
Order
Family
Genus
Species

2

Multiple Choice

What is an example of a species?

• Horses and their closest common ancestor.

• The animals that live in cave ecosystems

• Domestic Dogs (Husky, Lab, Beagle, etc.)

• The Birds (all birds of Earth)

Speciation

● Speciation is the evolution of new species over time

● Speciation is the rise of two or more species from

one existing species.

● Speciation occurs most rapidly in a small population

3

Open Ended

Why is speciation more rapid in small populations?

• The isolation of populations can lead to speciation.

• Populations become isolated when there is no gene flow.

• Isolated populations adapt to their own environments.

4

Speciation

Multiple Choice

What must STOP, in order for speciation to occur?

• Isolation must stop.

• Gene Flow must stop.

• Adaptation must stop.

• Mutations must stop.

Natural Speciation by
Reproductive Isolation

● Reproductive Isolation

occurs when members
of population can no
longer mate
successfully with one
another and produce
fertile offspring

5

Multiple Choice

What type of animal is this?

• Mammal

• Cartilaginous Fish

• Bird

• Mollusk

● Reproductive isolation is when members of a

population cannot interbreed and produce fertile
offspring

● Reproductive isolation can occur in a variety of

ways, including
○ Behavioral isolation
○ Geographic isolation
○ Temporal isolation

6

Natural Speciation by
Reproductive Isolation

Multiple Choice

Reproductive isolation means that members of a population...

• don't want to talk to each other.

• cannot interbreed and produce fertile offspring.

• Cannot find a mate.

• can interbreed and produce fertile offspring.

● Behavioral Isolation occurs when populations

are capable of interbreeding but have
differences in courtship rituals or other types
of behavior

● Example: Eastern and Western meadowlarks

use different songs to attract mates

Natural Speciation by

Behavioral Isolation

7

Multiple Choice

RECALL: What type of selection is a Bird's Mating Call?

• Intrasexual Selection

• Intersexual Selection

• Artificial Selection

• Unnatural Selection

Behavioral Isolation

Meadowlarks

9

Eastern Meadowlark

Western Meadowlark

Multiple Choice

Eastern and Western Meadowlarks have different mating calls. This is an example of...

• Natural Isolation

• Behavioral Isolation

• Temporal Isolation

• Geographic Isolation

● Geographical Isolation-Two populations are separated by

geographical barriers

● Geographical barriers: Mountain ranges, Deep

canyons, Bodies of water

○ Example:A population of Abert squirrels was separated

by the Colorado river and they evolved into two distinct
species

Natural Speciation by
Geographic Isolation

10

Draw

Create a geographic barrier between two populations.

Geographical Isolation

Kaibab and Abert squirrels

12

Multiple Choice

RECALL: If two phenotypes are preferred in an ecosystem we call that...

• Disruptive Selection

• Stabilizing Selection

• Directional Selection

• Interruptive Selection

● Temporal Isolation- Members of the same species

reproduce at different times

● Examples:

■ Plants that flower at different times

■ Animals that mate or nest build at different times

Natural Speciation by

Temporal Isolation

13

Multiple Choice

Why does it matter when plants flower?

• Flowers are plants' reproductive organs.

• Flowers look better in the daytime.

• Flowers need sunlight for photosynthesis.

• Flowers need to be close to each other to mate.

Temporal Isolation

● Speciation often occurs in patterns

● A pattern of punctuated equilibrium exists in the fossil

record

○ Episodes of speciation occur suddenly in geologic time

○ Followed by long periods of little evolutionary change

○ Revised Darwin’s idea that species arose through gradual

transformations

Speciation

15

Open Ended

What could cause rapid speciation?

Poll

What is the best review?

• Kahoot

• Gimkit

• Blooket

• Other

Top 3, get your prize