Transcript
EVOLUTION
Evolution• Change over time• Occurs to species, not individual
• Explains diversity on Earth today
Diversity• Great variety of types of living
things• Between species
– 10 – 100 million species on earth• Within a species• Result of evolution
Diversity
Diversitybacteria
phytoplankton
zooplankton
Diversity
sponges
mollusks
Diversityechinoderms
Diversity
Evolutionary Tree
How Evolution Works• Explained by Charles Darwin
and Alfred Russell Wallace• Darwin wrote On
the Origin of Species
How Evolution Works• Darwin visited Galapagos
Islands on HMS Beagle
How Evolution Works1. Overpopulation• more individuals born than
can survive
How Evolution Works2. Competition• for limited resources• some will survive, some will
not
How Evolution Works3. Variation• differences among individuals• a result of geneticmutation – changes inDNA
How Evolution Works4. Adaptation• some variation gives some
individuals a slight survival advantage
• these are favorable traits
How Evolution Works5. Natural Selection• those with best traits survive,
reproduce and pass favorable traits on to their offspring
• the mechanism of evolution
natural selectionresulting inreduced armor insticklebacks
How Evolution Works6. Speciation• changes build up and the
species changes over time
Adaptations• traits or characteristics that help an organism survive in its ecosystem
• three types:
Adaptations1. Structural- physical structure thathelps organism survive
Adaptations2. chemical
- chemical that helps organism survive
Adaptations
3. behavioral- behavior that helpsorganism survive
Adaptations
Camouflage• Allows an organism to
blend with its environment
AdaptationsWarning Coloration• bright colors make an
organism easily recognized
AdaptationsMimicry• one species is protected by
resembling another species or part of an organism
flatworm (right)mimicing atoxic nudibranch(left)
Isolation• if one part of a population is separated or
isolated from another, speciation is more likely
Isolation
Through the process of evolution by natural selection we have the great diversity of organisms that inhabit the Earth today.
For the rest of the school year we will be examining the results of evolution. We will study the adaptations of marine organisms and how they evolved over the 3.7 billion years that there has been life on Earth.
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