Changes in Organisms Over Time

1
Changes in Organisms Over Time
1
2
Age of Earth

• Scientist believe that the Earth is 4.6 Billion
  years old.
• Evidence
• Rock data, environmental changes

CLIP
2
3
Natural Selection

• Also know as survival of the fittest.
• Ones that are most suited to the environment.
• Only certain members of the population will
  survive and reproduce

3
4
What if the environment changes?

• The organisms that are most suited will survive,
  the others will die.
• This is a very slow process.does not occur over
  nightmany generations must past before any
  change in the population can be seen.

4
5
5
6
6
7
7
8
Example Peppered Moth
Two versions of the moth- Black and
Peppered During the industrial revolution on
England Population of moths changed WHY???
8
9
9
10
Decent with modifications
Organisms that were once the same have now grown
apart and have become different organisms.
Overtime natural selection produces organisms
that have different structures.
These changes increase a species fitness in
their environment.
10
11
History

• James Hutton -1785-Propsed that he Earth is
  millions of years old.
• Thomas Malthus -1798-populations outgrew food
  supplies, causing competition and a struggle for
  one species to survive against another
• Jean-Baptiste Lamark -inheritance of acquired
  characteristics

11
12
History Continued

• Lylle -1833-plant and animal species had arisen,
  developed variations, and then became extinct
  over time
• Alfred Russel Wallace -1858-idea of competition
  for resources as the main force in natural
  selection
• Charles Darwin -1859- Publishes On the Origin of
  Species

12
13
Charles Darwin
British Naturalist 1809 -1882 I have called
this principle, by which each slight variation,
if useful, is preserved, by the term Natural
Selection. Charles Darwin from "The Origin of
Species"
13
14
1831 to 1836-Darwin served as naturalist aboard
the H.M.S. Beagle on a British science expedition
around the world. In South America Darwin found
fossils of extinct animals that were similar to
modern species. Galapagos Islands - noticed many
variations among plants and animals of the same
general type as those in South America.
CLIP
14
15
Artificial selection- intentional breeding for
certain traits People have been artificially
selecting domesticated plants and animals for
thousands of years. Examples Broccoli and
brussels sprouts bear little superficial
resemblance to their wild mustard relatives
(left).
Humans select and breed for certain
traits. Examples The largest hog, the cow that
gives the most milk, or fastest horse.
15
16
Evidence for Change Over Time

• Fossil Record
• Fossils that show how the same organism looked
  millions of years ago.
• Use rock layers
• Isotope dating

16
17
Relative Dating
17
18
18
19
Homologous structures Structures that have
different mature forms in different organisms but
have developed from the same type of tissue.
19
20

• Embryology
• Early development of an organism

20
21
Stages of developmentfrom an embryo
21
22
Vestigial organs

• Organs or structures that do not seem to be used
  by the organism any longer.
• They are usually reduced in size.

22
23

• Evidence in Genetics to Show Change Over Time
• DNA sequences in organisms are close
• Sources of genetic variation in species
• Mutations
• Gene Shuffling
• Crossing over
• during meiosis

23
24
Speciation

• is the evolution of a new species
• occurs when interbreeding happens, or when the
  production of fertile offspring is prevented
• natural barriers form and cause the breakup of
  populations to form smaller populations
• Examples Volcanoes, sea-level changes, and
  earthquakes

24
25
Speciation Mechanisms
25

• Behavioral Isolation
• Populations are capable of interbreeding, but
  have different courtship rituals or other type of
  behavior.
• Geographic Isolation
• Separated by bodies of water or mountains.
• Temporal Isolation
• Reproduction takes place at different times of
  the year

• Overtime they can change so much that they become
  unable to breed as they adapt to their
  environment.

26

• Gene Pool
• Combined genetic information of a particular
  population.
• All the genes present with in a population
• Can change

26
27
Changes in allele frequency within a population

• Genetic drift
• Random changes in allele frequency that occurs in
  small populations
• Also know as the founder effect
• Populations may move into a new area and the
  alleles that carry with them will be passed on to
  their offspring.

27
28
3 Types of Evolution

• 1) Divergent
• 2) Convergent
• 3) Co-Evolution

29
Divergent Evolution

• Divergent evolution is the process of two or more
  related species becoming more and more
  dissimilar.
• ExThe red fox and the kit fox provide and
  example of two species that have undergone
  divergent evolution.

Red Fox
29
Kit Fox
30
Convergent Evolution

• the emergence of biological structures or species
  that exhibit similar function and appearance but
  that evolved through widely different
  evolutionary pathways.
• examples include the multiple origins of wings
  (bats, birds) and eyes.

30
31
Coevolution

• Examples
• Predators and their prey
• Parasites and their hosts
• Plant-eating animals and the plants upon which
  they feed
• plants and the animals that pollinate them.

Coevolution is the joint change of two or more
species in close interaction.
31
32

• Evolution is the change in a species over time.

32
33
Phylogenetic Trees

• Shows how closely organisms are related
• Are whales more closely related to camels or
  humans?
• Are snakes more closely related to birds or
  camels?

33
34
Phylogenetic Trees (cont.)
Which are more closely related, sharks and
amphibians or sharks and ray-finned fish? Which
2 species are the most closely related because
they have hair? How did you know
34
35
Rates of Evolution

• Gradualism
• Punctuated Equilibrium

35
36
Gradualism Punctuated Equilibrium

• A species can evolve by only one of these, or by
  both.

CLIP

• Species with a shorter evolution evolved mostly
  by punctuated equilibrium
• Species with a longer evolution evolved mostly by
  gradualism.

36
37

• Gradualism
• Very gradually, over a long time....
• Small variations that fit an organism slightly
  better to its environment are selected for
• Change is slow, constant, and consistent.

• Punctuated equilibrium
• change comes in spurts.
• period of very little change, and then one or a
  few huge changes occur
• often through mutations in the genes of a few
  individuals.

37
38
Resistance in Bacteria due to Evolution
38
Read page p403.
39
39
40
Two main sources of genetic variation

1. Mutations
2. Genetic Shuffling

40
41
EOCT- It is important that you are able to
explain how the concepts of genetics provide the
basis for explaining natural selection and
evolution. This will help you answer questions
like this

• What is the end result of natural selection?
• A increased number of offspring of a given
  phenotype that survive
• B changes in the frequency of alleles in a
  population
• C fossil formation through extinction
• D environmental changes of a habitat

41
42
Although the Arctic fox and the kit fox are
closely related, they look very different because
the individuals A acquired traits during their
lifetimes that contributed to survival B with
traits most suited to their environments
reproduced most successfully C migrated long
distances to environments that most suited their
traits D passed on to their offspring acquired
behaviors that were helpful
42
43
Fossils of Archeopteryx show that this animal
had feathers, like a bird. It also had a bony
tail, teeth, and claws on its wings, like a
reptile. This fossil is evidence that supports
the idea that A birds and reptiles have a common
ancestor B birds have changed very little over
150 million years C reptile species are more
advanced than bird species D reptiles are
warm-blooded like birds
43
44
Horses and tapirs have a common ancestor, but now
look very different. Horses now are grassland
animals adapted for grazing on grass and shrubs.
Tapirs are jungle animals that live in dense
forests and eat fruit, leaves and aquatic
vegetation. Which of the following led to the
development of such differences in the two
species? A selective breeding B convergent
evolution C DNA hybridization D natural selection
44