Download Concept 14.1 - Hatboro

Darwin Developed a Theory of Evolution
Ideas from Darwin’s Time
 A new view of life came into focus in 1859, when
Charles Darwin published his book the Origin of
Species, Darwin’s ideas provided a framework for
understanding Earth’s diversity of organisms and their
relationships to one another and their environment.
Evolution
 Generation-to-generation change in the proportion of
different inherited genes in a population that accounts
for all changes that have transformed life over an
immense time.
Adaptation
 An inherited characteristic that improves an
organism’s ability to survive and reproduce in a
particular environment.
The Voyage of the H.M.S. Beagle
 The intent of the voyage in 1831 was to set sail and
chart stretches of the South American coast. Darwin’s
job was to document the plants, animals and geology
encountered during the voyage, but more came from
it.
The Galapagos Islands
 This is an island area about 600 miles of the coast of
South America. Here Darwin made many
observations. There were many unique animals here
that were similar but different from the animals on the
mainland.
Descent with Modification
 He proposed that the descendants of the earliest
organisms spread into various habitats over millions of
years. In these habitats, they accumulated different
modifications or adaptations to diverse ways of life.
Natural Selection
 It is the process by which individuals with inherited
characteristics well suited to the environment leave
more offspring on average than do other individuals.
 Key to natural selection is offspring is not power or
speed, although this will help.
Concept 14.2
 Evolution has left much evidence.
Fossils
 Preserved remains or markings left by organisms that
lived in the past.
Fossil Record
 It is the chronological collection of life’s remains in the
rock layers, recorded during the passage of time.
Extinct
 These are species that no longer exists on Earth.
Similarities in Structure
 Homologous vs. Analogous
Homologous Structures
 These are characteristics that share a common
ancestor.
 The limbs of the following organisms:
 Human
 Cat
 Whale
 Bat
Analogous Structures
 These are structures that share no common ancestor.
 Wings of a bird and the wings of a bat.
Population Genetics
 It is the study of evolution from a genetic point of view.
Microevolution
 It is defined as a change in the collective genetic
material of a population. (Alleles)
Bell Curve
 It is a graph of the frequency of a particular
occurrence.
Gene Pool
 It is a term used to describe the total genetic
information available in a population.
Allele Frequency
 How often an allele occurs in a population.
Phenotypic Frequency
 It is equal to the number of individuals with a
particular phenotype divided by the total number of
individuals in the population.
Immigration
 It is the movement of individuals into a population.
Emigration
 It is the movement of individuals out of a population.
Gene Flow
 It is the process of genes moving from one population
to another.
Sexual Selection
 Possessing traits that favor the opposite sex for
reproductive means.
Stabilizing Selection
 Individuals with the average form of a trait have the
highest fitness.
Disruptive Selection
 Individuals with either extreme variation of a trait have
a greater fitness than individuals with the average form
of the trait.
Directional Selection
 Individuals that display a more extreme form of the
trait have a greater fitness than individuals with an
average form of the trait.
Speciation
 The process of species formation.
Geographic Isolation
 It is the physical separation of members of a
population.
Allopatric Speciation
 This happens when species arise as a result of
geographic isolation.
Reproductive Isolation
 It results from barriers to successful breeding between
population groups in the same area.
Sympatric Speciation
 It occurs when two subpopulations become
reproductively isolated within the same geographic
area.
Gradualism
 The idea that speciation occurs at a regular, gradual
rate.
Punctuated Equilibrium
 It refers to a sudden rapid change.