Transcript Unit 9: Evolutionary Biology

Chapters 14-17
 Change over time
 Spontaneous Generation: Living organisms arise from
non-living things.
 Many experiments were conducted to disprove
spontaneous generation.
SCIENTIST
DISPUTED
THEORY
CONCLUSIONS
Francesco Redi
(1600’s)
Maggots come
from rotting meat
Maggots come
from eggs laid by
flies
Lazzaro
Spallanzani
(1700’s)
Microorganisms
come from a vital
force in the air
Microorganisms
travel in the air
Louis Pasteur
(1800’s)
Boiling destroys
air’s vital force
Solid particles in
the air transport
microorganisms.
Redi—
Spallanzani—
 Pasteur--
Where did we come from?
 Formation of Simple Organic Compounds
 Alexander Oparin, 1923 (H2O, H2, CH4, & NH3)
 Formation of Complex Organic Compounds
 Amino acids formed chains in early atmosphere
 Concentration & Enclosure of Organic Compounds
 Coacervates & Microsphere formed
 Evolution of Growth, Metabolism, & Reproduction
 Approximately 4.6 – 3.5 billion years ago.
 First organisms – Prokaryotic cells
 Eukaryotic cells – 1 billion years ago
 Endosymbiont Theory – Eukaryotic mitochondria
evolved from bacteria & chloroplasts evolved from
cyanobacteria.
 We can find evidence of evolution by examining fossils
& modern day organisms
 Dating fossils
 Carbon-dating
 Position in sedimentary
rock
 Formation of the Fossil
Record
 Types of fossils:
 Mold
 Cast
 Imprint
 Common ancestry
 Hawaiian honeycreepers
 Homologous structures
 Similar embryologically,
have different functions
 Vestigial organs
 Functionless parts
 Biochemistry
 Similar biochemical metabolism
 Embryological Development
 Fish, rabbits, gorilla
but
 Jean Baptiste de Lamarck (1774-1829)
 Before Darwin
 Inheritance of Acquired Characteristics
 “If you don’t use it, you lose it”
 Natural Selection
 Organisms with favorable variations survive & reproduce
at a higher rate
 Variation exists among individuals of a species.
 Scarcity of resources in an increasing population will
lead to competition
 Individuals with advantageous variations are more
likely to survive & reproduce.
Type of
Environment
Two or more
species
Examples
CONVERGENT
EVOLUTION
Similar
DIVERGENT
EVOLUTION
Different
Similar but
unrelated
Cactus &
euphorbia
Related but
different
Red fox & kid
fox
 The joint change of two or more species in close
interaction.
 Example: Plants & animals that pollinate them
 Population
 All members of the same species living in a particular
location at the same time
 Gene Pool
 Collection of genes for all the traits in a population
 Allele Frequency
 Percentage of a specific allele of a gene in the gene pool
 Genetic Equilibrium
 Allele frequencies stay the same from generation to
generation
 A population will remain in GENETIC EQUILIBRIUM
if all of these conditions are met:
 No Mutations
 Individuals neither enter nor leave a population
 Population is large
 Individuals mate randomly
 Natural selection does not occur
 Mutation
 Migration
 Natural Selection
 Genetic Drift
 A phenomenon by which allele frequencies in a
population change as a result of random events or
change.
 Stabilizing Selection
 Favors average form (ex.
Lizard)
 Directional Selection
 Favors one extreme
form (ex. Anteaters)
 Disruptive Selection
 Favors both extreme
forms (ex. Limpets)
 Sexual Selection
 SPECIATION
 Formation of a new species.
 Geographic Isolation
 Physical separation of
members of a
populations
 Reproductive Isolation
 Results from barriers of
successful breeding
between population
groups in the same area