Download Natural selection

Mind Stretcher 3/9/16
1. Which of the following symbiotic relationships is
considered parasitic?
A.
B.
C.
D.
ticks taking nutrients from a dog
bees transporting pollen from flowers
pilot fish swimming under sharks
birds eating the insects from the back of a hippopotamus
2. Ants and acacia trees have a mutualistic
relationship because…
A.
B.
C.
D.
they benefit each other.
they are part of the same ecosystem.
they are both adapted to a humid climate.
the ants eat part of the acacia tree.
The Evolution of
Living Things
Georgia Performance Standards (GPS)

S7L5 Students will examine the evolution of living
organisms through inherited characteristics that
promote survival of organisms and the survival of
successive generations of their offspring.

S7L5.a Explain that physical characteristics of
organisms have changed over successive generations
(e.g. Darwin’s finches and peppered moths of
Manchester).

S7L5.c Trace evidence that the fossil record found in
sedimentary rock provides evidence for the long history
of changing life forms.
Let’s compare….
Rough Green Snake
Corn Snake
Key Vocabulary

A species is a group of organisms that can
mate with one another to produce fertile
offspring.
(fertile means can have offspring too!)

Speciation- the formation of new and distinct
species in the course of evolution.
Speciation
In their separate niches, the groups of shrimp go their own evolutionary ways,
accumulating different gene mutations, being subjected to
different environmental factors, experiencing different historical events, finally
becoming incapable of interbreeding should they ever come together again.
Key Vocabulary


A characteristic that helps an organism
survive and reproduce in its environment is
called an adaptation.

Examples of Adaptations: Hibernation,
Camouflage, migration, hair, resource
conservation
What type of adaptation is shown in the picture?
a. homologous structure
b. artificial selection
c. camouflage
d. mimicry
Camel Adaptations Rap

http://www.watchknowlearn.org/Video.aspx?
VideoID=53373&CategoryID=2855
Pay attention to the various ways camels are
ADAPTED to their environment…
Camouflage

The ability to blend into
the surrounding environment
is helpful when avoiding
a predator
Copy 2 examples!
Examples:
 Scorpionfish and leaf frogs- can change their
appearance to match their surroundings.
 Walking stick- looks very much like a twig
 Zebras fool would-be predators;

to a lion, they may look more like a mass of black-and-white
stripes than a delicious prey species!
Hibernation

EX: chipmunks, hedgehogs, bats and bears.
It’s usually quite difficult to stir these animals during
hibernation!
Migration

Movement of a population
of animals as they migrate
from one place to another

Reasons -finding food and a good place to mate.

Example- the arctic tern makes an annual migration
from its breeding grounds in the Arctic to its wintering
grounds in Antarctica, covering a distance of 25,000
miles!
Hair
• Hair offers important
protection from the
elements
• Musk Ox- Its thick, shaggy hair hangs down to the ground and
gives the ox the protection it needs to endure frigid temperatures
in the Alaskan tundra. (Winter temperatures= average of -30°F)
• Sheds some hair in time for summer, to itself cool down as
temperatures reach 40-50°F
Copy the red!
•
Resource
Conservation
Scarce/limited resources?
• Ability to conserve fat and
water in the body can mean
the difference between life
and death
• EX: Bactrian camel, a two-humped ungulate that lives in the rocky and
arid regions of Central and Eastern Asia, where temperatures range
from -20°F in winter to 100°F in summer.
• humps are filled with fat, which can be converted into energy and
water
• can forgo sweating until their body temperatures reach nearly
105°F.
Do species change over time?
Yes, The process in which
populations gradually change over
time is called evolution.

Ways Evolution Can Occur:

Punctuated Equilibrium: Species evolve
very rapidly and then stay the same for long
periods of time

Gradualism: Slow, constant change
Mind Stretcher:
The following statements describe the process of
speciation. Fill in the appropriate term in each sentence
and put them in the correct order in which they occur:
Terms: division, separation, adaptation
COPY- The process of speciation begins with

separation , when part of a population splits
________
apart. Because they respond to different
environmental conditions over time, organisms
traits evolve through adaptations
_________. Over time, the
two groups become so different they are no
longer able to interbreed. This is called
division
____________.
Quick Demonstration…
• As the “food source” comes around to
each table, QUICKLY pick out the 1st
M&M you see.
• The other food in the bucket is
poisonous (candy corn) and you may
NOT pick it!
• Set the M&M aside and wait to tally up the
class results. Do NOT eat them…some
have been used previously!
Think About It…

Which M & M colors were picked the
most? Why?

Relate the outcomes of the M&M activity to
camouflage in nature.

Give an example of an animal that uses
camouflage to avoid predators. Explain.
Evidence of change over time…

The remains or imprints of once-living
organisms found in layers of rock called
fossils.
Paleontologists work
among some of the
hundreds of fossilized
skeletons at
Nebraska's Ashfall
Fossil Beds.
Sedimentary
Rock
Formation


Formed from deposited sediments, as the
sediments build up, pressure increases,
pressure squeezes the bottom layers and
they form rocks. (lithification)
Laid down in layers or beds, younger beds
are above the older beds
Younger
Older
How do we get a fossil?
Fossils are RARE!
Using Fossils to Estimate Age

By identifying which layer of sediment the
fossil is found in, we can estimate the age of
the animal.
*Identify layer of fossil = estimate age!
REVIEW: The diagram below shows a geologic
cross section. Which rock layer most likely contains
fossils of the most recently evolved organisms?
A1
B2
C3
D4
MOST RECENT
OLDEST
Fossil Record
Scientists have made a
“timeline of life” known
as the fossil record. It
organizes fossils by
their estimated ages
and physical
similarities.
Scientists examine fossil
record to determine
relationships between
extinct and living
organisms.
Additional Evidence: DNA

DNA: Scientists can compare DNA
and find similarities among traits
Additional Evidence: Embryology

Embryology: During the very early stages
of life (in the womb), many organisms go
through similar stages of development.

Homologous Structures: Structures
derived from a common ancestor.
Homologous Structures (link to activity)
Evidence for Evolution Includes:
 FOSSIL RECORD

DNA & TRAITS

HOMOLOGOUS STRUCTURES

EMBRYOLOGY
Tree of Life Video clip (4 min)

http://www.watchknowlearn.org/Video.aspx?
VideoID=33080&CategoryID=4792
Ways to Show
Evolutionary Relationships:

Branching Tree Diagrams

“Tree of Life”- all species on Earth

BRANCHING TREE DIAGRAM- diagram/model
showing evolutionary relationships through shared
characteristics

Which species’ has a jaw and lungs, but does
not have claws or nails?
Tree of Life includes all
known
organisms on
Earth.
(Incomplete…
new species
always being
discovered)
Natural Selection and Adaptations
Natural Selection
What is Natural Selection? Natural selection is
the process by which individuals that are better
adapted to their environment are more likely to
survive and reproduce than other members of
the same species.
“Survival of the fittest!”
Who's Going
to Survive?
Charles Darwin &
Theory of Natural Selection…




British Naturalist aboard HMS Beagle
Collected animal & plant samples
Noticed variations among species…tortoise,
finches, etc.
Devised theory of natural selection
From 1 species to 14 species…
Warbler finch
Cactus finch
Woodpecker finch
Sharp-beaked finch
Small
insectivorous
tree finch
Large
insectivorous
tree finch
Small
ground
finch
Cactus
eater
Insect eaters
Seed eaters
Vegetarian
tree finch
variation
Bud eater
Medium
ground
finch
Large
ground
finch
natural selection for best
survival & reproduction
Finch Beaks
 different
beaks are inherited variations
 serve as adaptations
that help birds compete for food
 these birds (who got the food) survive &
reproduce
 pass on the genes for those more “fit”
beaks
 over time nature “selected” for different
species with different beaks
Relationship between species (beaks) & food
Natural Selection
Natural Selection
There are several factors that Darwin
identified that affect the process of natural
selection:
• Overproduction of offspring
• Competition
SKIP two lines
• Variations
between
each of these
factors!
Competition
Natural Selection
Overproduction
Variation
Overproduction
- Most species
produce far more
offspring than can
possibly survive
Competition
-Struggle between
organisms for the
limited resources
in a habitat
Variation
- Any
difference
between
individuals
of the same
species
Natural Selection: Examples
Are these two butterflies the same species?
These are the Monarch and Viceroy butterflies.
The Monarch on the left is poisonous and the Viceroy is not.
Question: Why would it be beneficial for the Viceroy to look like the
Monarch?
Natural Selection: Examples
Checkpoint: A species of hare
(rabbit) that is found in a cold
tundra environment. How are
oversized feet an advantage to
the Arctic Hare?
Natural Selection: Examples
How many moths do you see?
DIRECTIONS:
1. Go to my.hrw.com and login to the textbook
username: kilkenny11 password: x5s5d
2. Select "Go to Interactive Online Edition"
Go to Chapter 7 and click on E-Activities
(orange tab at the top)
3. Complete the Virtual Investigation