Download Bio 1010 Dr. Bonnie A. Bain

Bio 1010
Dr. Bonnie A. Bain
CHAPTER 13
Evolution
Part 2
The Theory of Evolution
Both Charles Darwin and Alfred Russell
Wallace came up with the mechanism
for evolution
Mechanism: natural selection
(more details later)
Figure 1.12
November 24, 1859
Origin of Species published
In this book,
Darwin lays out the evidence for the theory
of evolution by natural selection
Extra Photo 13.03x1
Extra Photo 13.03x2
Figure 13.00d
Darwin presented 2 main concepts in his
book:
1. Contemporary species arose from a
succession of ancestors through descent
with modification [Evolution]
2. Mechanism for evolution:
Natural Selection
Evolution or Descent with Modification
As descendants of the earliest organisms
spread into various habitats
over millions of years,
they accumulated different modifications to
diverse ways of life
The history of life is analogous to a tree
Patterns of descent are like the branching
and re-branching from a common trunk
Located at each fork (node) of the tree is
the common ancestor for all of the ones
above that node
Closely related species share many
characteristics because they both share a
common ancestor
Figure 13.6
Descent with Modification
Fig. 13-16
Lungfishes
Amniotes
Mammals
Tetrapod
limbs
Lizards
and snakes
Amnion
Crocodiles
Feathers
Hawks and
other birds
Birds
Ostriches
Tetrapods
Amphibians
Natural Selection
Evolutionary adaptations:
The results of natural selection
Adaptation:
An inherited characteristic that enhances an
organism's ability to survive and reproduce
in a particular environment
Figure 1.13
Adaptive
Radiation
Cultural and Scientific Context for Darwin's
Work
The view of life presented in The Origin of
Species contrasted sharply with prevailing
cultural views during Darwin's lifetime:
Earth was relatively young (6,000 yrs)
Lots of different species on Earth, but
they were not related to each other
Evolutionary thought prior to Darwin
Ancient Greece (2,500 years ago)
Anaximander (Greek philosopher)
Life originated in the water
Simplest forms evolved first
Gradually changed into more complex
forms
Ancient Greece (2,500 years ago)
Aristotle (Greek philosopher)
Species are fixed (permanent)
and do not evolve
Aristotle's ideas survived the Dark Ages and
influenced Renaissance science
1766
Georges Buffon
French naturalist, studied fossils
Earth much older than 6,000 yrs.
(based on fossil evidence)
Fossils are ancient versions of many
contemporary species
1809
Jean-Baptiste de Lamarck
Best explanation for fossils:
Life evolves
Mechanism for evolution:
Inheritance of acquired traits
Extra Photo 13.03x4
Jean-Baptiste de Lamarck
Mechanism for evolution:
Inheritance of acquired traits
By using or not using certain body parts, an
individual may develop (acquire) certain
traits which can be passed on to its
offspring
Example: Giraffe's long neck
Was Lamarck right??
Do we inherit acquired traits??
Whether or not Lamarck was right about
inheritance, he did help set the stage for
Darwin's ideas
(Darwin was born in 1809)
Also, Lamarck got lots of other things right
(described lots of new species, etc.)
Figure 13.3
Extra Photo 13.03x5
Next:
Charles Lyell
Scottish geologist
1830
Principles of
Geology