UNIT 1 Evolution & Classification

There are millions of different organisms on earth, the variety that exists among organisms is called… BIOLOGICAL DIVERSITY .
The questions many asked…
– What makes organisms so diverse?
– Could these diverse organisms be related in some way?
– How?

First of all a quick reminder of the term
THEORY….
– Well supported and test explanation that unifies a broad range of observations.
Evolution is a THEORY that states …
– GRADUAL change over TIME , is the process by which modern organisms have descended from ancient organisms

PBS VIDEO (Evolving Ideas)…
– Video: Isn’t Evolution Just a Theory? http://www.pbs.org/wgbh/evolution/library/11/2/quic ktime/e_s_1.html

LAMARK (1809)
– First to propose how organisms change, but theory is flawed
– Use and disuse of organs cause organism to change; organism change because they need to change; Ex: Bird doesn’t fly loses wings
DARWIN (1831)
– Sets sail on HMS Beagle, the voyage provides evidence that leads to his Theory of Evolution.
LYELL (1833)
– Geologist proposing the Earth has changed over time; thus organisms must also change

Collected Fossils….
– Fossils he collected
RESEMBLED organisms that were currently living.
Galapagos Islands west of
South America
– The Island had different climates
– Tortoises on 3 different islands were different on each Island to suit their climate

PBS VIDEO (Evolving Ideas)
– Video: Who Was Charles Darwin? http://www.pbs.org/wgbh/evolution/library/11/2/quic ktime/e_s_2.html

Natural Variation… there are differences among species; individual organisms differ ; alleles
Struggle for Existence… All organisms produce more offspring than can survive; therefore must compete for limited resources.
Natural Selection “Survival of the Fittest”… individuals best adapted for the environment survive and pass on traits to offspring .
Adaptation… any inherited characteristic that
INCREASES chance for survival

Evolution occurs because of Natural Selection
– Over time natural selection (nature) results in changes in the INHERITED characteristics .
– These changes are inherited and increase that species
FITNESS in its environment.
– Organisms more FIT for the environment, survive , reproduce , and pass on their genes (alleles).
Principle of Common Descent
– States that all species… living and extinct… were derived from common ancestors

PBS VIDEO (Evolving Ideas)
– Video: How does Evolution Really Work? http://www.pbs.org/wgbh/evolution/library/11/2/quic ktime/e_s_4.html

Natural Selection takes place because of genetic
VARIATION that exists in a population
– POPULATION – group of individuals of the same species that live in the same area
– GENE POOL – common group of genes shared by a population ( all the genetic information; alleles)
Sources of Genetic Variation
– Mutations – any change in the DNA sequence
– Gene Shuffling – change in allele frequency in a population; formation of gametes and crossing over allow for new gene combination (more variation)

Natural Selection acts on the PHENOTYPE
– It affects which individuals having different phenotypes survive and reproduce
– This is how natural selection determines which alleles are passed to next generation
– It changes the RELATIVE FREQUENCY of alleles in a population ( the number of one allele compared to the other in a population)

How would the gene pool be affected if these mice lived in an environment where the brown fur mice were more camouflaged?
48% heterozygous black
16% homoz black
Brown
Allele
Black
Allele
36% homozygous brown

Genetic Equilibrium (Allele frequencies stay the same) = NO Evolution
Hardy-Weinberg Principle Allele Frequencies will remain the same ONLY if ALL of the following …
– Random Mating (equal opportunity to reproduce)
– Very Large Population
– No migration in or out of population
– No Mutations
– No natural selection ( no phenotype has advantage)

How can natural selection and evolution lead to the formation of a new species ( speciation )
– Species is defined as a group of organisms that breed and produce fertile offspring (share the same gene pool)
New species are created when a population evolves and becomes reproductively isolated
(can not mate)

Behavioral Isolation
– They could breed, but do not because of differences in mating rituals (song birds)
Geographic Isolation
– Geography separates 2 species that use to breed
(rivers, mountains)
Temporal Isolation
– Species reproduce at different times (release pollen)

PBS VIDEO (Evolving Ideas)
– Video: How Do We Know Evolution Happens? http://www.pbs.org/wgbh/evolution/library/11/2/quic ktime/e_s_3.html

FOSSILS
– Show similar extinct organisms
GEOGRAPHIC
– Similar organisms in different locations
HOMOLOGOUS
STRUCTURES
– Similar body structures with different functions
– Some from common ancestors
VESTIGIAL ORGANS
– Organs that once had functions but not now
– Humans appendix
EARLY DEVELOPMENT
– Many vertebrates look similar as embryos
BIOCHEMICAL
– DNA, RNA are similar
– Use of ATP

TURTLE ALLIGATOR BIRD
MAMMAL
HOMOLOGOUS
STRUCTURES
PRIMITIVE FISH

PBS VIDEO (Evolving Ideas)
– Video: Why is Evolution Controversial Anyway?
http://www.pbs.org/wgbh/evolution/library/11/2/quic ktime/e_s_7.html

Ch 18

Taxonomy is the classifying of organisms and assigning a universally accepted name.
– Provides LOGICAL means for naming organisms
COMMON NAMES (misleading, differ from region, lengthy)
– EX: Groundhog is not a HOG, Sea Horse is not a HORSE
ARISTOTLE: Classified organisms in 2 categories…
– Plants or Animals
LINNEAUS: Binomial Nomenclature
– Two-Word (Latin) Naming System
– Currently used today as Scientific Name
– EX: Man is Homo sapiens

Binomial Nomenclature
FIRST WORD: Genus (noun)
– Broader category and may include many species
• EXAPMPLE: Homo (noun) means man
SECOND WORD: Species (adjective)
– More specific category
• EXAMPLE: Sapiens (adjective) means wise or thinking
Correct way to write
– Homo sapiens (italics when typed)
– Homo sapiens (underlined when hand written)

Categories (TAXA) based on…
– Structural and Functional similarities
– Lines of evolutionary descent
• CLADOGRAM – shows evolutionary relationship
– Similarities in DNA and RNA (biochemical)
• MOLECULAR CLOCK – use DNA to estimate how long species have evolved separately
– Developmental Similarities (embryological)

Explain the differences between traditional classification and cladograms (modern classification).
Appendages Conical Shells Crustaceans Gastropod
Crab Barnacle Limpet Crab Barnacle Limpet
TRADITIONAL
CLASSIFICATION
Molted exoskeleton
Segmentation
Tiny free-swimming larva
CLADOGRAM

Scientific Name: Homo sapiens)
K INGDOM (ex: Animal)
– K ids
P HYLUM (ex: Chordate)
– P refer
C LASS (ex: Mammal)
– C andy
O RDER (ex: Primates)
– O ver
F AMILY (ex: Hominid)
– F resh
G ENUS (ex: Homo)
– G reen
S PECIES (ex: sapiens)
– S pinach
KINGDOM Animalia
PHYLUM Chordata
CLASS Mammalia
ORDER Carnivora
FAMILY Ursidae
GENUS Ursus
SPECIES Ursus arctos

Turn to a friend.
Create your own Mnemonic device to remember classification from Kingdom thru Species…

EUBACTERIA
ARCHAEBACTERIA
PROTISTA
FUNGI
PLANTEA
ANIMALIA

DOMAIN
ARCHAEA
DOMAIN
BACTERIA
DOMAIN
EUKARYA
Kingdoms
Eubacteria
Archaebacteria
Protista
Plantae
Fungi
Animalia

DOMAIN
KINGDOM
CELL TYPE
CELL
STRUCTURES
NUMBER OF
CELLS
MODE OF
NUTRITION
EXAMPLES
Classification of Living Things
Bacteria
Eubacteria
Archaea
Archaebacteria
Prokaryote
Cell walls w/ peptidoglycan
Prokaryote
Cell walls w/out peptidoglycan
Protista
Eukaryote
Unicellular
Autotroph
Heterotroph
Unicellular
Autotroph
Heterotroph
Streptococc us, E. coli
Halophiles
Most unicell… some multi… some unicell…
Most multi…
Autotroph
Heterotroph
Hetero…
Amoeba,
Paramecium,
Fungi
Eukarya
Plantae
Eukaryote
Mushrooms, yeasts
Eukaryote
Multi…
Autotroph
Animalia
Eukaryote
Multi…
Heterotroph
Mosses, ferns, flowering plants
Sponges, worms, insects, fishes, mammals