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Diversity of Life
Mutations cause diversity by
DNA and as a result, proteins
changing _________________________
in cells
Sexual Reproduction causes diversity
by changing genetic combinations in
cells.
= GENE SHUFFLING
Diversity
• Estimated 5-30 million different kinds of
species on the earth
• All species share similarities such as the
genetic code, cellular structures, and
adaptations to ways of life
• Where did these different types of
organisms come from?
Evolution
• Theory – a well supported testable
explanation of phenomena that have
occurred in the natural world
• Evolution: The process that has
transformed life from it’s earliest beginning
to the unending diversity that exists today
• “Change over time”
Charles Darwin
• Joined H.M.S. Beagle in 1831
– Sailed around the world - 5 year voyage
– Observations from journey and collected evidence
(plant and animal specimen) lead to theory of
evolution
• Observations:
– most species were well suited to environment they
inhabited
– several ways in which organisms reproduced and
survived
Charles Darwin
• Fossil Collections:
– Some fossils resembled organisms that were
still alive
Heliobatis radians
(Common name; stingray or skate)
Eocene
Paratriakis curtirostris Fossil Shark
Cretaceous
– Other fossils did not resemble anything he
had ever seen
Eurypterus remipes
Upper Silurian
Published ideas in “Origin of Species”
Galapagos Islands
• Group of small islands 1000 km west of
South America
• Islands have very different climates
– Smallest, lowest islands were hot, dry, and
nearly barren (little vegetation)
– Higher islands had greater rainfall and a
different assortment of plants and animals
Galapagos Islands
Galapagos Islands
• Characteristics of many animals and
plants varied noticeably among the
different islands
• Did these separate species have a
common ancestor?
Galapagos Islands
• Tortoises differed from island to island
• Shape of the tortoise’s shell could be used
to tell which island it was from
More Rainfall
Less Rainfall
Galapagos Tortoises
Galapagos Tortoise photo by theBIGzoo.com
Photo courtesy Marc Shandro.
Photograph by Charlotte (AKA, "moxythecat")
Galapagos Islands
• Darwin also studied
several types of small
brown birds
– Had different shaped
beaks
– Assumed they were
all different kinds of
birds
– Later noticed that the
birds he collected
from the different
islands were all
finches
/www.galapagosonline.com/nathistory/wildlife/birds/galapagosbirds.htm
Santa Cruz. Medium ground
finch (female), Geospiza fortis.
Large ground finch (female?), Geospiza
magnirostris.
Small ground finch (female),
Geospiza fuliginosa.
Struggle for Existence
Organisms compete for resources
- not enough materials/space for all organisms born
Survival of the Fittest
Organisms have differences = adaptations
- adaptations are inherited characteristics
- physical, behavioral
Ex.=
- adaptation have to be suitable for the
environment
- adaptations help organisms survive,
increase fitness.
Survival of the Fittest
Organisms that are better fit are more likely to survive
Organisms that survive get to reproduce
Organisms that reproduce pass their genes and
thus their adaptations to the next generation
Assignment:
Guppy Natural Selection Simulation
Common Descent
Offspring of the same parents exhibit genetic variability
Variability allows them to inhabit different niches
i.e.: compromise
NICHE = physical and biological conditions that
an organism lives with AND the way it uses those
conditions
Downy Woodpeckers
Males forage on small trees or on small
branches of large trees;
Females forage on the trunks and larger
limbs of large trees.
Example of Niche in Warbler Species
Left to right: Cape May, Yellow-rumped, Black-throated Green,
Blackburnian, and Bay-breasted Warblers.
Black areas in stylized conifers show where feeding is concentrated.
Common Descent
Eventually descendents of common ancestors may be very
different from each other = Descent With Modification
Ex. Gazelle species feeding at different times
Dama Gazelle:
active during daytime
Arabian Sand Gazelle:
active at twilight
Common Descent
Over time organisms gain different adaptations
and become different species
= EVOLUTION
New species shared common ancestors
A single “Tree of Life” can be made for all organisms
Formation of New Species
Species = a population that cannot interbreed with
another population and produce fertile offspring
Gene pools must be separated somehow for species to develop
Isolating Mechanisms
- create separate gene pools
Behavioral Isolation:
- habitats overlap
- courtship behaviors differ
Ex. = Bird mating calls, courtship dances
Geographical Isolation:
- habitats are separated by geographical feature
Ex. = lakes separate fish species,
Colorado River separates squirrel species
Temporal Isolation:
- habitats overlap
- reproduce at different times
Ex. = orchids pollinate on different days,
Diversity
Taxonomy – discipline of classifying
organisms and assigning each organism a
universally accepted name
• Grouping organisms by similarities has
given taxonomists the present day system
of classification
• Organisms placed into a particular group
are more similar to each other than they
are to organisms in another group
Kingdoms and Domains
• The three-domain system
Bacteria
Archaea
Eukarya
• The six-kingdom system
•
Eubacteria Archaebacteria
•
Plantae
Fungi
• The traditional five-kingdom system
•
Monera
Protista
•
Fungi
Animalia
Protista
Animalia
Plantae
Three-Domain System
•
Domain is a more inclusive category than
any other – larger than a kingdom
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Eukarya
Bacteria
Archaea
Eukarya
• Composed of protists, fungi, plants and
animals
Bacteria
• Correspond to the Kingdom Eubacteria
– Unicellular
– Prokaryote
Archaea
• Correspond to Kingdom Archaebacteria
– Unicellular
– Prokaryote
– Live in some of the most extreme
environments
• Volcanic hot springs, brine pools, black organic
mud devoid of oxygen
Linnaeus’s System of Classification
(Largest to Smallest)
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Kingdom (You already know these 5!!)
Phylum
Class
Order
Family
Genus
Scientific Name
Species
K
P
C
O
F
G
S
Binomial Nomenclature
• Each species is assigned a two-part
scientific name
– Always written in italics
– First word is the genus
• Group of closely related species
• Always capitalized
– Second word unique to each species within
the genus
• Always lowercase
Classifying Organisms Using
Dichotomous Keys
• Dichotomous keys can be used to identify
unfamiliar organisms
• A series of paired statements that describe
physical characteristics of different organisms
• Paired statements are always opposite
statements and lead to more detailed statements
which eventually determine the identity of the
organism