EVOLUTION
EVOLUTION AS A SCIENTIFIC THEORY
Scientific Theory
A well-supported, testable explanation
Takes into account all known observations, experiments, and data
HISTORY OF THE UNIVERSE
Big Bang
15 billion years ago
Formed all matter of the universe
Earth formed as a result of the Big Bang
Fully formed 4.6 billion years ago
STEPS TO THE EVOLUTION OF
MULTICELLULAR LIFE
Heterotroph Hypothesis
Proposed by Oparin and Haldane
Three criteria for life to originate on Earth
1. Inorganic molecules combined to form organic
molecules
2. Organic molecules combined to form complex polymers
3. Polymers organized themselves into a system that could
replicate itself
STEPS TO THE EVOLUTION OF
MULTICELLULAR LIFE
1. Formation of basic chemicals of life
2. Formation of pre-cells
3. Formation of proteins
4. Evolution of prokaryotes
5. Increase of oxygen in the atmosphere
6. Evolution of eukaryotes
STEPS TO THE EVOLUTION OF
MULTICELLULAR LIFE
1. Formation of basic chemicals of life
Chemical reactions on early Earth changed simple inorganic molecules into complex organic ones
Tested by Miller & Urey
Produced amino acids
Repeated similar experiments have
produced other complex organic compounds
Tested by Cairns
Clay could have attracted and catalyzed bonding of
STEPS TO THE EVOLUTION OF
MULTICELLULAR LIFE
2. Formation of pre-cells
In the right conditions organic molecules can form “bubbles” called proteinoid microspheres and
coacervates
Characteristics similar to cells
STEPS TO THE EVOLUTION OF
MULTICELLULAR LIFE
3. Formation of first proteins
Experiments (Miller/ Urey, Cairns) show
RNA could form and replicate on its own
Simple RNA probably existed as genetic
STEPS TO THE EVOLUTION OF
MULTICELLULAR LIFE
4. Evolution of
prokaryotes
If RNA or DNA became trapped in a microsphere, it would have formed the first prokaryotic cell
Reproduction through asexual reproduction Heterotrophic
STEPS TO THE EVOLUTION OF
MULTICELLULAR LIFE
5. Increase of oxygen in the atmosphere
Early prokaryotes were likely photosynthetic
Produced oxygen as a waste product
STEPS TO THE EVOLUTION OF
MULTICELLULAR LIFE
6. Evolution of eukaryotes
Endosymbiotic Theory
Smaller prokaryotes taken up by larger prokaryotes Developed a mutually helpful, or interdependent, relationship
STEPS TO THE EVOLUTION OF
MULTICELLULAR LIFE
7. Sexual reproduction and multicellularity
Offspring produced
from a combination of parent cells
Offspring unique
Populations became diverse
Colonies combined together to form multicellular organisms with
MICROEVOLUTION AND NATURAL
SELECTION
Darwin’s Theory of Natural Selection
Influenced by
Hutton:
Earth was much older than previously believed
Lyell:
Geologic processes changed Earth over time
Malthus:
Populations cannot continue to grow without running out of resources
Lamarck:
Theory of Acquired Characteristics, which was rejected based on the laws of genetics
Artificial Selection:
MICROEVOLUTION AND NATURAL
SELECTION
Darwin’s Theory of Natural Selection
Main ideas: Variation
Genetic difference between members of a species
Adaptation
Variations that aid in survival
Struggle for existence
Members of a species are in constant competition
Fitness
Ability to survive and reproduce
Descent with modification
Species descend from other species over time, with changes
Common Descent
MIRCOEVOLUTION AND NATURAL
SELECTION
Darwin’s Theory of Natural Selection
Organisms do not change to fit into their environment
Random mutations result in variations
Some variations are adaptations that aid in survival
Organisms that survive will have like offspring
EVIDENCES FOR EVOLUTION
Fossils
Comparative Anatomy (Unity of Pattern)
Biochemical Analysis
EVIDENCES FOR EVOLUTION
Fossils
The fossil record groups and arranges organisms in the order which they lived to show how species have changed over time
The fossil record is incomplete
No sediment in areas to bury for the process to occur
Organisms decay or are eaten by predators and scavengers Rocks with fossils erode away
EVIDENCES FOR EVOLUTION
Fossils
Relative Dating
Comparing placement with other fossils as well as known index fossils
Radioactive Dating
Using radioactive isotopes and information about their
EVIDENCES FOR EVOLUTION
Comparative Anatomy
Comparing structures and functions of organisms to determine evolutionary relationships
EVIDENCES FOR EVOLUTION
Comparative Anatomy
Homologous structures
Similar structures indicate common ancestry Vestigial structures
Homologous structures with little or no purpose in the organism
Embryology
Homologies in development indicate common ancestry
Analogous structures
Different structures with similar functions
EVIDENCES FOR EVOLUTION
Biochemical Analysis
Comparison of DNA, amino acids, and/or proteins to
determine a genetic
relationship to common ancestry
EVIDENCES FOR EVOLUTION
Geographic distribution
Scientists propose that species dispersed when the continents were connected and were later carried to their present positions as the continents drifted
Isolated organisms then adapted and changed over time in their new environment
Similarities show how the populations are related
MACROEVOLUTION AND SPECIATION
Microevolution leads to macroevolution
Small-scale changes over time (microevolution) can accumulate and lead to large-scale changes
(macroevolution) over a long period of time
Macroevolution can result in speciation
SPECIATION
Geographical isolation
Organisms that cannot geographically come into contact cannot interbreed
Ecological isolation
Organisms that have adapted to different habitats cannot interbreed
Behavioral isolation
Organisms that have developed different courting, premating, or mating behaviors will cannot interbreed
Seasonal isolation
Organisms that mate at different times of the year cannot interbreed
Physical/Mechanical isolation
MACROEVOLUTION AND SPECIATION
Patterns of macroevolution
Divergent evolution (adaptive radiation) Convergent evolution
Coevolution Extinction Gradualism
MACROEVOLUTION AND SPECIATION
Divergent evolution (adaptive radiation)
Common ancestor splits into different groups
Associated with homologous structures
Convergent evolution
Unrelated organisms come to resemble one another due to similar environmental demands
Associated with analogous structures
Coevolution
MACROEVOLUTION AND SPECIATION
Extinction
The dying out of a group of organisms
Gradualism
The idea that change in populations occurs slow and steadily over time
Punctuated Equilibrium
The idea that change in populations
PRIMATES
Common ancestor
65 million years ago
Diverged into differing groups Humans most
closely related to chimpanzees
Branch