Download Evol Theory, Evidence

Evolutionary Theory
 The Theory of Evolution is based on many types of
data.
 Fossil Record
 Morphological Evidence
 Embryological Evidence
 DNA Evidence
Homologous Structures
 Body parts with the
same structures but
have different
functions
Analogous Structures
 Body parts with
similar functions but
with different anatomy
(not good evidence)
Vestigial Structures
 Body parts that are
reduced in size and
are no longer used
 Hip bones in snakes
have no purpose, but
they suggest that
snakes evolved from
ancestors with hips
Embryological Structures
 Different species
have similar
embryos
 At certain stages
of development
many animal
embryos are
difficult to identify
Theories of Evolution
 Jean Baptiste Lamarck (1744 – 1829)
 Theory of Acquired Characteristics
1. Living species descended from a
common ancestor (True)
2. Acquired characteristics could be
passed on to offspring (False)
-an acquired trait is one that is not
determined by genes.
Ex.-birds’ feet, giraffe necks
Charles Darwin
 Darwin (1809 -1882)
 Darwin studied many
animals but the
finches from the
Galapagos Islands
were of great interest
to him.
The Journey
Galapagos Islands
Finches
 Finches on different
islands had different
characteristics.
 It is thought that a
single species from S.
America flew to the
islands and the
different islands
caused the finches to
evolve.
. Charles Darwin (1830)
 1. Overproduction
 2. Struggle for existence
(survival)
 3. Variation
 4. Survival of the fittest
 5. Natural selection
 6. Evolution of new species
Natural Selection
 The environment
selects the most-fit
organisms.
 The environment
selects organisms
with beneficial traits
Natural Selection
 Variation exists within a species
 Among members of a species, traits vary
Natural selection is based on . . .
 Non-random survival
 Albino squirrels
 Non-random mating
 Mate selection
 Woman’s choice
 Non-random fecundity
 Production of offspring
Advantageous
Traits/Adaptations
 MIMICRY- advantage gained by copying the
appearance of another, more dangerous, species.
 Ex.- flies and hornets
 CAMOUFLAGE- advantage gained by blending in w/
surroundings.
 Ex.- walking stick, tiger, leaf fish, etc.
Types of Natural Selection
 Stabilizing Selection Individuals with the
average form of a trait
have the highest
fitness
Types of Natural Selection
 Directional Selection Extreme forms of a
trait are more fit
Types of Natural Selection
 Disruptive Selection Either extreme form
of a trait is more fit.
Patterns of Evolution
 Coevolution
 The change of two or
more species in close
association with each
other
 Parasites & host,
predator & prey
Patterns of Evolution
 Convergent Evolution
 The environment
selects similar
phenotypes even
though the organisms
are quite different
 Sharks and dolphins
Patterns of Evolution
 Divergent Evolution
 Two or more related
populations or
species become more
and more dissimilar.
 Galapagos finches