Transcript Darwin`s Theory of Evolution

Evolution—change over time,
the process by which modern
species have descended from
ancient organisms
Darwin’s Theory of Evolution
Who was Charles Darwin?
http://www.pbs.org/wgbh/evolution
/library/11/2/e_s_2.html
Fossil—preserved remains of
ancient organisms
1. Geospiza magnirostris.
2. Geospiza fortis.
3. Geospiza parvula.
4. Certhidea olivawea
Artificial Selection—selection by
humans from natural variation
among different organisms for
breeding of useful traits
Fig. 22-9
Terminal
bud
Lateral
buds
Cabbage
Brussels sprouts
Flower
clusters
Leaves
Kale
Cauliflower
Stem
Wild mustard
Flowers
and stems
Broccoli
Kohlrabi
• Other examples of Artificial Selection?
Selective Breeding—method of
improving a species by allowing
only those individual organisms
with desired characteristics to
produce offspring
Hybridization—breeding
technique that involves crossing
dissimilar individuals to bring
together the best traits of both
organisms
•Other example of hybridization?
Genetic engineering—the
process of making changes in
the DNA code of living
organisms
Ex.-inducing mutations to increase
genetic variation
Fig. 17-6
(a) Tobacco plant expressing
a firefly gene
(b) Pig expressing a
jellyfish gene
Natural variation—genetic
differences among individuals
of a species
Genetic variability starts with
natural mutations
Fig. 22-10
Struggle for Existence—
members of each species
compete regularly to obtain
food, living space, and other
necessities of life
Adaptation—any inherited
characteristic that increases
an organism’s chance of
survival
Camouflage as an example of
evolutionary adaptaition
Signate Melanophila Moth
Pandora Sphinx Moth
Polyphemus Moth
Luna Moth
A flower mantid
in Malaysia
A stick mantid
in Africa
Fig. 23-14a
(a) Color-changing ability in cuttlefish
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Fig. 23-14b
Movable bones
(b) Movable jaw
bones in
snakes
Question: What would happen if a
well-adapted population experienced
a sudden major change in its
environment
Answer: If the population had
a variety of traits some of
them may survive and
reproduce in the new
environment, if not they would
probably become extinct
Fitness—the ability to survive
and reproduce viable offspring
Descent with modification—
principle that each living species
has descended, with changes,
from other species over time
Common descent—principle
that all living things have a
common ancestor
Homologous structures—
structures that have different
functions but develop from the
same embryonic tissue
Fig. 22-17
Humerus
Radius
Ulna
Carpals
Metacarpals
Phalanges
Human
Cat
Whale
Bat
Vestigial organs—organs that
serve no useful function
Early development
The early embryos of many
animals with backbones are so
similar that they can be hard to
tell apart
Fig. 22-18
Pharyngeal
pouches
Post-anal
tail
Chick embryo (LM)
Human embryo
Biogeography
The study of the past and present
distribution of species