Transcript Lesson Overview

Darwin’s Voyage of Discovery
Lesson Overview
Lesson
Overview
16.1 Darwin’s Voyage
of Discovery
Darwin’s Voyage of Discovery
Lesson Overview
Darwin’s Epic Journey
Evolution: process of change over time
Darwin developed a scientific theory of biological
evolution that explains how modern organisms
evolved over long periods of time through descent
from common ancestors.
Darwin published his first complete work on evolution: On
the Origin of Species
He sailed on the HMS Beagle’s for five-years ,
mapping the coastline of South America.
Darwin’s Voyage of Discovery
Lesson Overview
Darwin observed 3 patterns of
Biodiversity
1. Species vary globally – different yet
ecologically similar animals are found in
different yet similar environments.
2. Species vary locally – different yet related
species occupy different habitats in one area.
3. Species vary over time – fossils of extinct
species are similar to current species.
Darwin’s Voyage of Discovery
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Evolution
The Earth is old and the process of
change exists today.
Traits acquired during an organism’s
lifetime are NOT passed to it’s
offspring!
Most organisms don’t survive to
reproduce!
Examples: sea turtles, insects, etc.
Darwin’s Voyage of Discovery
Lesson Overview
Common descent!
Common descent – all species (living and
extinct) descended from a common
ancestor!
Over many generations, adaptations caused
a successful species to evolve into a new
species!
The fossil record provides evidence for this
descent with modification!
Darwin’s Voyage of Discovery
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Evidence of descent from common
ancestors:
1. Geographic distribution of
species
2. Fossils
3. Anatomy (homologous
structures)
4. Physiology (analogous
structures)
5. Embryology
6. Universal genetic code
Darwin’s Voyage of Discovery
Lesson Overview
Artificial selection
Nature provides variation in
organisms’ traits, but
humans choose to breed those
organisms
that have the most useful traits.
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Example: humans breed cows that
produce the
most milk.
Example: humans breed trees that
create the
most fruit.
Darwin’s Voyage of Discovery
Lesson Overview
Natural Selection
Natural selection is the process by which
organisms with variations most suited to their
local environment survive and reproduce.
By surviving, these attributes can be passed
onto their
children, causing an
increase of these traits in the species
population, thus causing a gradual change in
the
characteristics of the population.
Individuals whose characteristics are not
well-suited to
their environment die or leave few offspring.
Because natural selection favors a certain trait
over
others, more individuals in the population
carry the
genes for that trait.
survival of the fittest
.
Darwin’s Voyage of Discovery
Lesson Overview
Species Vary Locally- Finches
Adapted from one original
species. Due to different food
availability.
Darwin’s Voyage of Discovery
Lesson Overview
Darwin’s Voyage of Discovery
Lesson Overview
The scarlet king snake exhibits mimicry—an
adaptation in which an organism copies, or mimics,
a more dangerous organism. Although the scarlet
king snake is harmless, it looks like the poisonous
eastern coral snake, so predators avoid it, too.
A scorpionfish’s coloring is an example of
camouflage—an adaptation that allows an
organism to blend into its background and avoid
predation.
Darwin’s Voyage of Discovery
Lesson Overview
Fitness describes how well an
organism can survive and reproduce
in its environment.
Individuals with adaptations that are
well-suited to their environment can
survive and reproduce and are said to
have high fitness.
Darwin’s Voyage of Discovery
Lesson Overview
Darwin’s Voyage of Discovery
Lesson Overview
PHYSIOLOGY
Analogous structures Body parts that share
a common function, but not structure.
Examples: a bat’s wing and a moth’s
wing--both are
wings and both are
used for flight, but a bat has bones
and a moth does not.
Vestigial Structures- body structures that have
reduced or no body function
As species adapt to environments the change
in form and behavior and continue to inherit
these structures as part of the body even
though they
have no function.
Examples: A human’s appendix, a
whale’s pelvis!
Darwin’s Voyage of Discovery
Lesson Overview
ANATOMY
Homologous structures – similar in structure but
differ in function!
parts of different organisms (that are often quite
dissimilar) that developed from the same
ancestral body parts!
Forelimbs of whales, bats, crocodiles, and chickens
have similar anatomy but are modified for different
functions – common Ancestry!