• Chapter 15 Section Assessments: Due Block Day
(4/16 or 4/17)
• Chapter 15.1 SA: p. 372 (1-4)
• Chapter 15.2 SA: p. 377 (1-4)
• Chapter 15.3 SA: p. 386 (1-3)
• Chapter 15 Assessment: p. 389 (1-10, 15, 18, 21,
23)
• Species
• Evolution
• Theory
• Fossil
• Artificial selection
• Struggle for existence
• Fitness
• Adaptation
• Survival of the fittest
• Natural selection
• Descent with
modification
• Common descent
• Homologous structure
• Vestigial organ
• The Puzzle of Life’s Diversity
• Ideas That Shaped Darwin’s Thinking
• Why do scientists use a classification system?
• To organize many diverse organisms (biological
diversity)
• What is a theory?
• A well-supported ,testable explanation of
phenomena that have occurred in the natural world.
• What is evolution?
• Change over time; process by which modern
organisms have descended from ancient organisms
• Charles Darwin: British scientist who made a
significant contribution to the understanding of
evolution; traveled with a sailing crew around
the world on the H.M.S. Beagle
• Key Concept: 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.
• Key concept: Darwin observed that the
characteristics of many animals and plants
varied noticeably among the different islands
of the Galápagos.
• Patterns of diversity: plants and animals
“matched” their environments
• Fossils of ancient organisms sometimes
resembled living organisms (Fig. 15-2)
• Characteristics of animals on the Galápagos
varied from island to island due to climate
change (Fig. 15-3)
• Darwin’s voyage occurred during a time of
great change in the perspective of the natural
world.
• At the time, many people believed that the
world was only several thousand years old.
• Key Concept: Hutton and Lyell helped scientists
recognize that Earth is many millions of years
old, and the processes that changed Earth in the
past are the same processes that operate in the
present.
• James Hutton and Geological Change
• Hutton proposed the rock formations occur over
millions of years at a very slow rate (Fig. 15-6)
• Charles Lyell’s Principles of Geology
• Darwin received a copy of Lyell’s book before his
voyage on the Beagle.
• Lyell proposed that processes that currently shape
Earth must be used to explain processes that shaped
Earth in the past.
• Darwin concluded that if Earth takes many years to
change, so should life on Earth.
• Key Concept: Lamarck proposed that by
selective use or disuse of organs, organisms
acquired or lost certain traits during their
lifetime. These traits could then be passed on to
their offspring. Over time, this process led to
change in a species.
• Jean-Baptiste Lamarck’s Evolution Hypotheses
(c.1809)
• Tendency toward perfection: all organisms have
an innate tendency toward complexity and
perfection (i.e. fiddler crabs, Fig. 15-7)
• Use and disuse: Organs that are not used will
decrease in size over generations and finally
disappear.
• Inheritance of acquired traits: these changes
are passed on to future generations (i.e. body
builders will have children with big muscles too)
• Key Concept: Malthus reasoned that if the human
population continued to grow unchecked, sooner or
later there would be insufficient living space and food
for everyone.
• Thomas Malthus and Population Growth
• English economist who stated that war, famine and disease
are the only factors working against population growth
Darwin Presents His Case
• Darwin’s On the Origin
of Species
• Darwin waited more than
25 years before he
published his thoughts on
evolutionary change.
• He received both positive
and negative reviews.
• What did Darwin’s work
actually say?
• Darwin observed how breeders used
heritable variations in organisms.
• Artificial Selection
• Key Concept: In artificial selection, nature
provided the variation, and humans selected
those variations that they found useful. (Fig. 510)
• Natural Selection
•Population growth would eventually lead to
competition for limited resources.
• Struggle for existence: members of each
species compete regularly to obtain food,
living space, and other necessities of life.
• Natural Selection
• Fitness: ability of an individual to survive and
reproduce in its environment.
• Adaptation: any inherited characteristic that
increases an organism’s chance of survival.
• Survival of the fittest: Individuals better suited for
their environment survive and reproduce more
successfully over individuals who are not well suited.
• Descent with modification: each living species has
descended, with changes, from other species over
time. (change over time)
• Natural Selection
•Read: 1st paragraph on page 382
• Common Descent: All species, living and
extinct, were derived from common ancestors.
•Did you catch the jump from microevolution to
macroevolution?
• Key Concept: Darwin argued that living things
have been evolving on Earth for millions of
years. Evidence for this process could be found
in the fossil record, the geographical
distribution of living species, homologous
structures of living organisms, and similarities in
early development, or embryology.
• The Fossil Record: comparison of fossils found in
old and young rock layers and discovery of
transitional fossils (Fig. 15-13)
• Geographic distribution of species: organisms in
different geographic locations share similar
features due to adaptation to similar climates.
(Fig. 15-14)
• Homologous body structures: have different
mature forms but develop from the same
embryonic tissues (Fig. 15-15)
• Vestigial organs: organs that decrease in size over
time (Fig. 15-16)
• Similarities in embryology: many embryos look
similar in early stages of development (Fig. 1517)