Download 10th abbreviated evolution - Hatboro

EVOLUTION
http://www.pbs.org/wgbh/evolution/
Charles Darwin
Voyage of the Beagle
The Galapagos Islands
• Dates: Left England in 1831, Arrived @
Galapagos in 1835
• 13 Islands: each with a different climate and
ecosystem
• Darwin Collected Fossils & live organisms from
each island:
– Tortoises: variations in shell
– Finch Birds: variations in beak and color
– Blue-Footed Boobies
– Marine Iguanas
Animals
Darwin’s Conclusion
• Variation: Individual organisms in a species look
different from one another
• Hypothesis: New species could appear
gradually due to small changes in an original
species
– Cannot see the changes occur, so looked to
BREEDING
Natural Selection vs. Artificial Selection
• Artificial selection- nature provides the
variation among different organisms, and
humans select those variations they find
useful.
– Ex. BREEDING
Evolution by Natural Selection
“Nature Selects”
• The Struggle for Existence:
– members of each species have to compete
for food, shelter, other life necessities
• “Survival of the Fittest”:
– Some individuals better suited for the
environment due to physical traits
– Allows them to REPRODUCE & pass on
genetic traits
Struggle For Existence & Survival of The
Fittest
Natural Selection
• Four Principles of Natural Selection
–Individuals in a population show
differences, or VARIATIONS
–Variations are INHERTIED (genes)
–Organisms have more offspring than
available resources
–Any variations that increase survival are
passed on to future generations
Types of Natural Selection
“Fur color”
• Directional Selection (Dark OR Light)
• Stabilizing Selection (Medium)
• Disruptive Selection (Dark AND Light
Darwin’s Theory of Evolution
• Published a book, On the Origin of Species by
Means of Natural Selection, in 1858
• Used the term “evolution” on the LAST PAGE!
• Evolution, or change over time, is the process by
which modern organisms have descended from
ancient organisms.
Evidence of Evolution
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The Fossil Record
Geographic Distribution of Living Things
Comparative Anatomy
Similarities in Embryology
Biochemistry
• http://science.discovery.com/tv-shows/greatestdiscoveries/videos/evolution.htm
Evidence for Evolution
• The Fossil RecordLayers in Earth’s crust
show change
• The deeper the fossil,
the older it is
• Compare old and
new fossils
Evidence of Evolution
• Geographic Distribution of Living Things:
Organisms that live in similar environments
have similar characteristics, even if far
apart
Evidence of Evolution
• Comparative Anatomy
– Homologous Structures: anatomically similar
structures inherited from a common ancestor
– Analogous Structures: structures that are
anatomically different, but have the same
purpose, came from different ancestor
– Vestigial Organs: organs that do not serve a
purpose, lost through evolution and mutation
(ex. Appendix, tail
Evidence for Evolution
• Comparative Embryology: embryos of
different organisms are similar, came from
common ancestor
Adaptation
• Basis of Natural Selection
• Organisms CANNOT choose to have an
adaptation…controlled by DNA
• Adaptation increases FITNESS: ability to
survive and reproduce
Types of Adaptation
• Camouflage: ability to blend with environment
• Mimicry: ability to resemble another species
http://www.thefeaturedcreature.co
m/category/endangered-species
Mary
River
Turtle
Skull
Caterpillar
(Australia)
Glauert's seadragon
Human Ancestors
• 99% identical DNA between Humans and Apes
• Australopithecus africanus: small brain, big teeth,
walked on all 4 limbs
• Homo habilis: larger brain, 1st to use tools, smaller
molars
• Homo erectus: first to always stand completely upright,
most “human” like qualities
• Homo neaderthalensis: unsimilar mitochondrial DNA
and Y-chromosome material, scientists think they were
separate species, no our ancestors!
• Homo sapien : US
“Finding Lucy”
• http://www.youtube.com/watch?v=SPit_Mca
8dM
“Ardi”
• Ardipithecus ramidus – 1992
– 50kg Female
– Missing “step” between chimp
and human; had both sets of
characteristics
– Bipedal on land, Quadruped in
trees
EVOLUTION FUN FACTS…
• Homo sapiens is still evolving rapidly.
• Homo sapiens has only had a culture for less than
50,000 years.
• The human population crashed about 80,000 years
ago.
• Humans have incredibly low genetic diversity.
• We Share 70% of our DNA with a Slug.
Causes of Evolution
• If alleles in a population remain the same,
evolution will remain at EQUILIBRIUM; no
change.
• Disruptions of Equilibrium:
– Mutations (changes in DNA)
– Natural selection (change in environment causes
certain traits to be more favorable)
– Random mating (mating outside of the population)
– Genetic Drift
– Gene Flow
Genetic Drift
• Change in allele frequency
• Founder Effect: small group of organism
settle in an area separated from population
– Ex. Amish People
• Bottleneck Effect: population declines in size,
then rebounds
– Ex. Northern Elephant Seals – Humans hunted
them, population decreased, now less variation in
current populatioin
Gene Flow
• Genes/traits in a population remain the same until
new organisms enter or leave the population
Speciation
• Formation of a new species
• Allopatric
– Creation of a new species due to a physical
barrier
– Ex. Grand Canyon; Kaibab vs Abert Squirrel
• Sympatric
– Creation of a new species without a physical
barrier
– Ex. Several insects and plants, change in
chromosome number
Patterns of Evolution
• Adaptive Radiation
– Aka Divergent Evolution
– Species diverged from a single ancestor
– Usually due to different environments
• Coevolution
– Species evolve in close relationship with other
species
• Convergent Evolution
– Unrelated species evolve to form similar
adaptations, due to living in similar environments
Coevolution of
Humans & Dogs!
Evolution video shorts
• http://www.pbs.org/wgbh/nova/evolution/litt
le-people-flores.html evolution of
…HOBBITS?!
• http://www.pbs.org/wgbh/nova/evolution/de
coding-neanderthals.html decoding
neanderthals
• http://www.pbs.org/wgbh/nova/evolution/w
hat-makes-us-human-pro.html becoming
human
Hmm…Ha Ha Ha!
• Are humans the only species that can laugh?
• Why do we laugh?
• Does the ability to laugh help organisms to
survive?
• http://www.pbs.org/wgbh/nova/evolution/evolu
tion-laughter.html evolution of laughter!