Chapter 15: Evolution
I. DARWIN’S THEORY OF EVOLUTION BY NATURAL SELECTION
A. Developing the Theory of Evolution
1. collected rocks, fossils, plants, and animals
2. Influenced by other scientists
a. Lyell’s Principles of Geologyb. Gould’s discovery of finch speciesc. Malthus’s essay on human population growthB. The Galapagos Islands
1. each island had specific species
2. populations of finches changed after reaching ____________________________
C. Darwin continued his studies
1. Hypothesis: new species could appear through ______________________________
___________________________________________________________________________
2. Artificial Selection- process of directed breeding to produce offspring with desired traits
a.
b.
D. Natural Selection
1. Process in which competitors struggle for existence and some of those competitors would be better
equipped for survival than others.
2. Basic principles for how a trait can change over time
a. Variation: Individuals in a population will differ from each other
b. Heritability: variations are genetic (kids will often look like parents)
c. Overproduction: Populations produce more offspring than needed
d. Advantage: Some individuals will have variations that allow them to live better and
reproduce more (and their offspring will look like them)
3. Given enough time, natural selection could modify a population so much it would produce a new
species
E. The Origin of Species
1. book of evidence and explanation of how natural selection provides the mechanisms for the origin
of species
2. evolution- changes in groups of organisms over time
a. evolution does not change an _________________________!!!
b. natural selection is only one mechanism of evolution
Draw a population of any species. Circle an individual.
II. EVIDENCE OF EVOLUTION
A. Support for Evolution
1. Fossil record
a. shows how ancient species are similar to current species
b. transitional fossils- show changes from ancestral to current species
2. Anatomy
a. homologous structures- anatomical structures inherited from common ancestor but modified
function
1.)
2.)
b. Vestigial structures-structures that functioned in ancestral species that are inherited but do not
function
1.)
2.)
3.)
c. Analogous structures
1.) definition:
2.) example:
3. Embryology
a. Vertebrate embryos exhibit homologous structures during certain phases of development
but become totally different ______________ in the ____________ form.
b. The shared features in the early embryos suggest ___________________ ______________________
4. Biochemistry
a. Molecules in species with a recent common ancestor should share certain amino acid sequences
b. The more closely related the species are, the greater ______________________________________
5. Geographic distribution
a. biogeography: distribution of
b. climate and plate tectonics explain
B. Adaptation
1. Fitness:
2. Types of Adaptation
a. camouflage
1. allows organisms to become almost invisible to predators
2. advantageous because __________________________________________________________________
b. mimicry
1. one species
2. advantageous because __________________________________________________________________
C. Features can be adaptation or consequences…
III. SHAPING EVOLUTIONARY THEORY
A. Mechanisms of Evolution: Natural selection is not the only mechanism of evolution!
1. Population Genetics
a. Hardy-Weinberg principle
b. genetic equilibrium will be held if allelic frequencies do not change
1.) large population size
2.) no immigration or emigration
3.) mating is ____________________
4.) no mutations
5.) no ________________ ___________________
2. Genetic Drift: change in allelic frequencies from CHANCE
a. Founder effect
1.)definition:
2.)example:
b. Bottleneck:
1.)definition:
2.)example:
3. Selective Pressures
a. Stabilizing selection
1.)definition:
2.)example:
b. Directional selection:
1.)definition:
2.)example:
c. Disruptive selection:
1.)definition:
2.)example:
4. Convergent Evolution vs. Adaptive Radiation
a. Adaptive Radiation (divergent evolution)
1.) Many species diverge from one ancestral species
2.) due to different environmental pressures
b. Convergent Evolution
1.) Species do not share a close common ancestor
2.) Similar environmental pressures leads to evolution of similar traits