EVOLUTION
Jean-Baptiste Lamark:
1744-1829
•
•
•
most famous for incorrectly theorizing
on the process of evolution
As a giraffe stretches its neck to reach
for food, its neck grows longer; this
trait is passed to offspring
did not realize that acquired traits are
not genetic
Tree of Life
Sometimes the variation among organisms is too great;
eventually they could become separate species
SPECIATION: the development of a new species
SPECIES: a population of organisms that can produce
fertile offspring
X
HORSE – Equus caballus
MULE
DONKEY – Equus assinus
Allopatric Speciation:
two populations are separated by geographic
barriers such as rivers, mountains, bodies of
water, etc.
Ex: Albert Squirrel and Kaibab Squirrel
PANGAEA:
• a proposed supercontinent
that formed over 300 million
years ago
• Began separating 200 million
years ago
Allopatric Speciation:
two populations are separated by geographic
barriers such as rivers, mountains, bodies of
water, etc.
Ex: Albert Squirrel and Kaibab Squirrel
Sympatric Speciation:
two populations are reproductively isolated;
commonly due to polyploidism
Parapatric Speciation:
two populations living in the same geographic
area become different species due to different
selective pressures
BEHAVIORAL
Ex: Eastern Meadowlarks & Western Meadowlarks
have different mating songs
TEMPORAL
Ex: flowers blooming at different seasons
DIVERGENT EVOLUTION:
evolution of different features from similar lineages
DIVERGENT EVOLUTION:
evolution of different features from similar lineages
DIVERGENT EVOLUTION:
evolution of different features from similar lineages
DIVERGENT EVOLUTION:
evolution of different features from similar lineages
Divergent Evolution and Homologous Structures
show how certain species may have come from the
same ancestor
CONVERGENT EVOLUTION:
evolution of similar features from different lineages
CONVERGENT EVOLUTION:
evolution of similar features from different lineages
CONVERGENT EVOLUTION:
evolution of similar features from different lineages
CONVERGENT EVOLUTION:
evolution of similar features from different lineages
CONVERGENT EVOLUTION:
evolution of similar features from different lineages
Convergent Evolution and Vestigial Structures
show how different species adapt to similar environments
CONVERGENT
different becomes
same
DIVERGENT
same becomes
different