Download Chapter 15 - Western High School

Chapter 15
Evolution
Section 15.1
• Darwin’s Theory of Evolution by Natural
Selection
– Charles Darwin developed a theory of
evolution based on natural selection
– Darwin on the HMS Beagle
– Galapagos Islands
– Artificial selection: (selective breeding)-the
process of directed breeding to produce
offspring with desired traits
Natural Selection
• Those better equipped for survival are able to
reproduce
• Four basic principles
– Individuals in a population show differences or
variations
– Variations can be inherited
– Organisms have more offspring than can survive on
available resources
– Variations that increase reproductive success will
have a greater chance of being passed on
Natural Selection
• Given enough time, natural selection could
modify a population enough to produce a
new species
• Figure 15.3 page 421 Natural selection in
a sunflower
Basic Principles of Natural
Selection
• Individuals in a population show variations
among others in the same species
• Variations are inherited
• Animals have more young than can
survive on the available resources
• Variations that increase reproductive
success will be more common in the next
generation
The Origin of Species
• Book written by Darwin compiling his work
• Evolution used to define cumulative
change in groups of organisms through
time
• Natural selection is not synonymous with
evolution: it is a mechanism by which
evolution occurs
Section 15.2
• The theory of evolution states that all organisms
on Earth have descended from a common
ancestor
• Evidence of Evolution
– Multiple lines of evidence support the theory of
evolution
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The fossil record
Comparative anatomy
Comparative embryology
Comparative biochemistry
Geographic distribution
The fossil record
• Derived traits – newly evolved structures
(feathers) do not appear in the fossils of
common ancestors
• Ancestral traits – more primitive features
(teeth, tails) that do appear in ancestral
forms
Comparative Anatomy
• Homologous structures – anatomically
similar structures inherited from a common
ancestor (reptiles and birds)
• Vestigial structures – structures that are
the reduced forms of functional structures
in other organisms (snake pelvis, kiwi
wings, human appendix)
Comparative Anatomy
• Analogous structures – structures that can
be used for the same purpose and can be
superficially similar in construction but are
not inherited from a common ancestor
(wings of eagle vs. wings of beetle)
Comparative Embryology
• Bird and mammal
embryos share
several
developmental
features
– Tails
– Pharyngeal pouches
Comparative Biochemistry
• Amino acid
sequences
– Cytochrome c
– Figure 15.9 page 427
Geographic Distribution
• Biogeography – the field of study that links
climate and geological forces (plate
tectonics) to ancestral relationships and
geographic distribution seen in fossils and
living organisms today
Adaptation
• Types
– Camouflage
• Ability to blend in with environment
– Peppered moths
– Mimicry
• One species evolves to resemble another
– California Kingsnake and Western Coral Snake
– Antimicrobial resistance
• Some species of bacteria have developed drug
resistance
– MRSA
Consequences of Adaptations
• Not all features of an organism are
necessarily adaptive.
• Some features might be consequences of
other evolved characteristics
– Spandrel
• Architectural consequence to support dome
– Human
• Helplessness of human babies
• Ability to walk upright and big brains