1. EVOLUTION

2. Early scientists proposed ideas about evolution.
KEY CONCEPT There were theories of biological and geologic change before Darwin.
Early scientists proposed ideas about evolution.
Evolution is the biological change process by which descendants come to differ from their ancestors.
There were many important naturalists in the 18th century
Linnaeus
Buffon
E. Darwin
Lamarck

3. Theories of geologic change set the stage for Darwin’s theory.
There were three theories of geologic change.
Catastrophism
gradualism
Uniformitarianism

4. Darwin observed differences among island species.
KEY CONCEPT Darwin’s voyage provided insight on evolution.
Darwin observed differences among island species.
Variation is a difference in a physical trait
An adaptations is a feature that allow an organism to better survive in its environment.
Species are able to adapt to their environment.
Adaptations can lead to genetic change in a population
Darwin observed fossil and geologic evidence supporting an ancient Earth.
found extinct animals looking like modern
fossils up in the Andes mountains

5. Several key insights led to Darwin’s idea for natural selection.
KEY CONCEPT Darwin proposed natural selection as a mechanism for evolution.
Several key insights led to Darwin’s idea for natural selection.
Artificial selection
Natural selection is a mechanism by which individuals that have inherited beneficial adaptations produce more offspring on average than do other individuals.
Darwin proposed that adaptations arose over many generations.
There are four main principles to the theory of natural selection.
variation
overproduction
adaptation
descent with modification

6. Natural selection can act only on traits that already exist.
Structures take on new functions in addition to their original function.

7. Evidence for evolution in Darwin’s time came from several sources.
KEY CONCEPT Evidence of common ancestry among species comes from many sources
Evidence for evolution in Darwin’s time came from several sources.
1. Fossils
2. Geography
3. embryology
4. anatomy
Homologous structures- similar structure different function
Human hand
Bat wing
Mole foot

8. Analogous structures -similar function.
Analogous structures are not evidence of a common ancestor.
Human hand
Bat wing
Mole foot
Fly wing
Vestigial structures are remnants of organs or structures that had a function in an early ancestor.

9. KEY CONCEPT New technology is furthering our understanding of evolution.
Paleontology is the study of fossils or extinct organisms.
Molecular and genetic evidence support fossil and anatomical evidence.
Pseudogenes are sequences providing evidence of evolution.
Hox genes indicate a very distant common ancestor.
Protein comparisons, or molecular fingerprinting reveals similarities among cell types of different organisms.
Evolution unites all fields of biology.

10. KEY CONCEPT A population shares a common gene pool.
Genetic variation in a population increases the chance that some individuals will survive.
Genetic variation leads to phenotypic variation.
Phenotypic variation is necessary for natural selection.
Genetic variation is stored in a population’s gene pool.
Genetic variation comes from several sources
Mutations
Recombinations
Hybridizations

11. KEY CONCEPT Populations, not individuals, evolve.
Natural selection acts on distributions of traits.
normal distribution
Natural selection can change the distribution of a trait in one of three ways.
directional selection- favors extreme phenotype
stabilizing selection- favors intermediate phenotype
disruptive selection- favors both extreme phenotypes

13. KEY CONCEPT Natural selection is not the only mechanism through which populations evolve.
Gene flow is the movement of alleles between populations.
Genetic drift is a change in allele frequencies due to chance.
Genetic drift causes a loss of genetic diversity.
It is most common in small populations.
A population bottleneck can lead to genetic drift.
Sexual selection occurs when certain traits increase mating success.
intrasexual selection: competition among males
intersexual selection: males display certain traits to females

14. KEY CONCEPT Hardy-Weinberg equilibrium provides a framework for understanding how populations evolve.
Hardy-Weinberg equilibrium describes populations that are not evolving.
Genotype frequencies stay the same if five conditions are met.
very large population: no genetic drift
no emigration or immigration: no gene flow
no mutations: no new alleles added to gene pool
random mating: no sexual selection
no natural selection: all traits aid equally in survival
Real populations rarely meet all five conditions

15. used for traits in simple dominant-recessive systems
The Hardy-Weinberg equation is used to predict genotype frequencies in a population.
used for traits in simple dominant-recessive systems
must know frequency of recessive homozygotes
p2 + 2pq + q2 = 1
"The Hardy-Weinberg equation is based on Mendelian genetics. It is derived from a simple Punnett square in which p is the frequency of the dominant allele and q is the frequency of the recessive allele."

16. There are five factors that can lead to evolution.
1. Genetic drift changes allele frequencies due to chance alone.
2. Gene flow moves alleles from one population to another.
3. Mutations produce the genetic variation needed for evolution.
4. Sexual selection selects for traits that improve mating success.
5. Natural selection selects for traits advantageous for survival.
In nature, populations evolve.
respond to changing environments

17. KEY CONCEPT New species can arise when populations are isolated.
The isolation of populations can lead to speciation
Populations become isolated when there is no gene flow
Reproductive isolation can occur between isolated populations.
Speciation is the rise of two or more species from one existing species.
Populations can become isolated in several ways
Behavioral barriers can cause isolation.
Geographic barriers can cause isolation.
Temporal barriers can cause isolation

18. KEY CONCEPT Evolution occurs in patterns.
Evolution through natural selection is not random
Convergent evolution describes evolution toward similar traits in unrelated species.
Divergent evolution describes evolution toward different traits in closely related species.
Two or more species can evolve together through coevolution.
Coevolution can occur in beneficial relationships.
Coevolution can occur in competitive relationships, sometimes called evolutionary
Species can become extinct
Background extinctions occur continuously at a very low rate.
Mass extinctions are rare but much more intense. (5 have occurred)
Many species evolve from one species during adaptive radiation.

19. Coevolution
adaptive radiation

20. KEY CONCEPT The origin of life on Earth remains a puzzle.
Several sets of hypotheses propose how life began on Earth.
Organic molecule –
1. Miller-Urey
2. meteorite
There are different hypotheses of early cell structure
iron-sulfide bubbles
lipid membrane
A hypothesis proposes that RNA was the first genetic material.
electrodes
heat source
amino acids
water
“atmosphere”
“ocean”

21. KEY CONCEPT Single-celled organisms existed 3.8 billion years ago.
The oldest known fossils are a group of marine cyanobacteria.
prokaryotic cells
added oxygen to atmosphere
deposited minerals
Fossil stromatolites provide evidence of early colonies of life.
Eukaryotic cells may have evolved through endosymbiosis.

22. Eukaryotic cells may have evolved through endosymbiosis
Mitochondria and chloroplasts may have developed through endosymbiosis.

23. The evolution of sexual reproduction led to increased diversity.
KEY CONCEPT Multicellular life evolved in distinct phases.
Life moved onto land in the middle of the Paleozoic era.
Reptiles radiated during the Mesozoic era.
Mammals radiated during the Cenozoic era.
Anatomically modern humans appeared late in the era.

24. KEY CONCEPT Humans appeared late in Earth’s history.
Humans share a common ancestor with other primates.
Primates evolved into prosimians and anthropoids.
Anthropoids are humanlike primates
Bipedal means walking on two legs.
Most hominids are either the genus Australopithecus or Homo.
Homo sapiens fossils date to 200,000 years ago
Australopithecus
afarensis
Homo habilis
Homo
neanderthalensis
Homo sapiens