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5. Evolution and Biodiversity
• Central Concepts: Evolution is the result
of genetic changes that occur in constantly
changing environments. Over many
generations, changes in the genetic makeup of populations may affect biodiversity
through speciation and extinction.
• 5.1 Explain how evolution is demonstrated
by evidence from the fossil record,
comparative anatomy, genetics, molecular
biology, and examples of natural selection.
Chapter 15-1 The Puzzle of Life’s
Diversity
• 1809 Charles Darwin – Father of Evolution.
Naturalist from England. Sailed on the surveying
ship HMS Beagle and traveled to various lands.
• During his travels, Darwin made numerous
observations and collected evidence that led him
to propose a revolutionary hypothesis about the
way life changes over time.
Darwin’s Observations

Patterns of Diversity – organisms seemed well suited to
their environment! There were SO many different types of
similar organisms (68 different types of beetles in the Brazilian
rainforest). Was there such way that leads to variety. Why were
certain types or organisms only found in certain areas? How
were they so well suited for their environment?

Living Organisms and Fossils – Darwin collected the
preserved remains of ancient organisms from many places
(fossils). Why have so many species disappeared and how were
they related to living things.
  The Galapagos Islands – One of the most influential places
- off the coast of S. America. They were close together – they
have very different climates very different organisms (from hot,
dry  nearly barren; lots of plants  few plants).
 Finches – 16 different types of birds – differed in color
and beak shape (based on what they ate.
o Tortoises – varied from one island to another.
Darwin observed that the characteristics of many
animals and plants varied noticeably among the different
islands of the Galapagos
15-3 Darwin Presents His Case
• Darwin put his thoughts and evidences into a book (title above).
• Inherited variation and artificial selection
• Artificial Selection – nature provided variation, and human selected
those variations that they found useful. Horse/dog breeders; farm
animals (breed the best ones – not the worst)
• Natural Selection – process by which individuals that are better suited
to their environment survive and reproduce most successfully (survival
of the fittest)
  Fitness – ability to survive and reproduce
  Adaptation – any inherited characteristic that increases an
organism’s chance of survival.
  Descent with modification – over long time, natural selection
produces organisms that have different structures, establish different
niches, or occupy different habitats. (that’s why they look different
from their ancestors)
EVIDENCES FOR
EVOLUTION
• Darwin argued that living things have been
evolving on earth for millions of years.
FOSSILS
• Preserved remains of ancient organisms
• fossils lower in rocks and mountains are
older than those in higher areas. They also
show that organisms changed a LOT over
time. Gaps remain in the fossil record.
HOMOLOGOUS BODY
STRUCTURES
structures that have different mature
forms but develop the same embryonic
tissue. Provide evidence that all fourlimbed vertebrates have descended with
modifications from common ancestors.
VESTIGIAL ORGANS
• organs of many animals are so reduced in
size that they are just vestiges, or traces of
homologous organs in other species. It may
not affect an organisms ability to survive
and reproduce, so natural selection did not
eliminate the organ
EMBRYOLOGY
early stages of embryos of many animals
with backbones are very similar. They
look really similar.
4 Evidences for Evolution
•
•
•
•
1. Fossils
2. Homologous Structures
3. Vestigial Organs
4. Embryology
DARWINS THEORY
1. Individual organisms differ, some
variation is heritable
2. organisms produce more organisms than
survive
3. Organisms compete for limited resources
4. Most fit organisms survive
5. species alive today are descended with
modification
17-1 The Fossil Record
• Paleontologists: scientists who study
fossils
• The fossil record provides evidence about
the history of life on Earth. It also shows
how different groups of organisms,
including species, have changed over time.
• 99.9% of anything that was ever living on
this earth is now extinct.
• Most fossils form in sedimentary rock, as
shown in the figure at right. Sedimentary
rock is formed when exposure to rain, heat,
wind, and cold breaks down existing rock
into small particles of sand, silt, and clay.
• In relative dating, the age of a fossil is determined by
comparing its placement with that of fossils in other
layers of rock, as shown in the figure at right. Recall that
sedimentary rock is formed from the gradual deposition
of layers of sand, rock, and other types of sediment. The
rock layers form in order by age—the oldest layers on the
bottom, with more recent layers on top, closer to Earth's
surface.
• Relative dating allows paleontologists to estimate a
fossil's age compared with that of other fossils.
• 5.2 Describe species as reproductively
distinct groups of organisms. Recognize
that species are further classified into a
hierarchical taxonomic system (kingdom,
phylum, class, order, family, genus,
species) based on morphological,
behavioral, and molecular similarities.
Describe the role that geographic isolation
can play in speciation.
SECTION 18-1 Finding Order in
Diversity
• SCIENTISTS HAVE IDENTIFIED MORE THAN 2 MILLION
SPECIES OF ORGANISMS ON EARTH, BUT ESTIMATE 40
MILLION SPECIES INHABIT THE EARTH.
 
A Universal System is necessary to have clear communication
among scientists worldwide. A system that required an International
System for Classifying and Naming all organisms.
 
2,000 years ago Greek philosopher Aristotle classified things
as either Plant or Animal and then as land dwellers, water dwellers and
animal dwellers.
 
Scientists found that Using COMMON NAMES, such as robin or
fir tree, for an organism presented its own problems; common names
varied from on locale to the next and common Names May Not
describe species accurately.
 
Carols Linnaeus in the mid-1700s, Swedish Biologist
established a simple system for classifying and naming organisms
(taxology). He developed a Hierarchy for classifying organisms based
on morphology (using what it looks like to categorize it)
Today we have SEVEN LEVELS OF
CLASSIFICATION:
•
A. KINGDOM (largest classification)
B. PHYLUM
C. CLASS
D. ORDER
E. FAMILY
F. GENUS
G. SPECIES (smallest classification)
KING PHILIP CAME OVER FOR GRAPE SODA.
  BINOMIAL NOMENCLATURE is a 2 name system
based on the organims’s genus and species.
•
• SAMPLE: Acer rubrum - RED MAPLE TREE
•
Acer is the Latin name for Maple (genus)
•
rubrum is the Latin word for Red (species)
•
OR THE NAME CAN BE ABBREVIATED AS:
A. rubrum.
•
HUMANS ARE NAMED: Homo sapiens
•
Homo because of our large brain and upright posture.
sapiens because of our intelligence and ability to
speak.
CHAPTER 18-2 Modern
Evolutionary Classification
• When placing an organism into a Taxonomic
Category, Modern Taxonomists May consider its:
• MORPHOLOGY (what it looks like)
• CHROMOSOMAL CHARACTERISTICS
• NUCLEOTIDE (DNA AND RNA) AND
AMINO ACID SEQUENCES
• EMBRYOLOGICAL DEVELOPMENT
• FOSSIL RECORD
SECTION 18-3, Kingdoms
and Domains
• THE SIX-KINGDOM SYSTEM
• 5.3 Explain how evolution through natural
selection can result in changes in
biodiversity through the increase or
decrease of genetic diversity within a
population.
16-3 The process of speciation
• Factors such as natural selection and
chance events can change the relative
frequencies of alleles in a population. But
how do these changes lead to the formation
of new species, or speciation?
ISOLATING MECHANISMS:
1. Reproductive Isolation: As new species evolve,
populations become reproductively isolated from each
other and can no longer produce fertile offspring.
2. Behavioral Isolation: when two populations are capable
of interbreeding, but have differences in courtship rituals
or reproductive strategies that involve behavior.
3. Geographic Isolation: two populations are separated by
geographic barriers such as rivers, mountains or bodies
of water.
4. Temporal Isolation: two or more species reproduce at
different times.
17-4
PATTERNS OF EVOLUTION
• PATTERNS OF EVOLUTION
• important topics in macroevolution are
1. EXTINCTION: 99.9% of all species ever on this earth are now
extinct. Mass extinction. (most extinctions today are due to human
activity)
2. ADAPTIVE RADIATION: a single species or small group have
evolved into different forms that live in different ways. Ex.
FINCHES, homologous structures
3. CONVERGENT EVOLUTION: Unrelated
organism come to resemble one another. Ex.
Dolphin/sharks
4. COEVOLUTION: process by which 2 species are
closely connected to one another by ecological
interactions evolve together. Ex. Plants and plant
eating insects
5. PUNCTUATED EQUILIBRIUM: some
groups of organism have evolved rapidly
after a mass extinction