Transcript Principles of evolution

Principles of evolution, our heritage
and the Origins of Life
What was life like a long time ago?
How did we come into being?
How do we know this?
What is the process?
Evolutionary History



Darwin did not come up with his theories all by
himself.
Many others set up a foundation that would allow
Darwin to think as he did.
Others came up with the same theory
Independently
Bio 130 Human Biology
The “species problem”


Why do populations of organisms change over
time?
If an organism is present in a particular area, it
must be perfect for that area, so why then do
exotic species pose a threat?
Bio 130 Human Biology
Evolution vocabulary words




Evolution: Change in lines of descent
over time.
Microevolution: series of changes that
give rise to a new species (population).
Macroevolution: major large scale
patterns of change in groups of living
organisms.
Population: a group of individuals of the
same species
Bio 130 Human Biology



Populations evolve not individuals.
Populations exhibit great variability. When
this variability changes over time is when we
get new species. (micro evolution)
Sources of variation within a population



mutations create new alleles
crossing over during meiosis leads to new
combinations of alleles
independent assortment mixes alleles
Bio 130 Human Biology
Microevolution Processes





Mutation
Natural selection
Genetic Drift
Gene flow
Reproductive isolation
Bio 130 Human Biology
Mutation


Any heritable change in
DNA sequence.
Three types




lethal mutation
neutral mutation
beneficial
The vast majority of
mutations are probably
invisible or harmful.
Bio 130 Human Biology
Natural selection:


Is the major process to produce populations
that have different characteristics.
First described by Darwin


If a trait is more adaptive it improves the chances
of producing offspring (adaptation)
It gives more of its alleles to the following
generation (greater fitness)
Bio 130 Human Biology
Genetic drift:



Random fluctuation of
allele frequencies over
time
Works better in small
populations
Influenced by who
starts a population


Inhabitants of Pitcairn island,
descendants of the 7 Bounty
Mutineers
Bio 130 Human Biology
Bottleneck effect
Founder effect
Gene Flow:


Genes flow with the
individuals of a
population
Physical flow tends to
minimize genetic
variation, like shuffling
the deck.
Bio 130 Human Biology
Reproductive Isolation and
speciation



Species: are populations of individuals that
can interbreed.
When separated by 10,000 or more
generations many species can no longer
interbreed.
Types of isolation

geographic, behavioral, biochemical
Bio 130 Human Biology
Rates of evolutionary change



Gradualism: Evolution is a slow and methodical
process
Punctuated equilibrium: Evolution occurs in rapid
bursts followed by long periods without change
Adaptive radiation: numerous branches from a
single point on an evolutionary tree. Typically
follows periods of change (a big dieoff)
Bio 130 Human Biology
Evidence for Microevolution




Fossil record
Comparative
morphology
Comparative
biochemistry
Biogeography
Bio 130 Human Biology
How Fossils are formed
Fig 22.1
The process of
fossilization
Homologous
structures share a
common origin
Fig 22.4
Early developmental
similarity among
vertebrate embryos
Fig 22.5
Bio 130 Human Biology
We do not go through evolution
during embryogenesis, we just
share homologous structures and
vestigial structures
Comparative biochemistry


Human Birth control works in Chimpanzees
Cytochrome C a protein of 104 AA length





Exactly the same in Humans and Chimps
1 AA difference in rhesus monkeys
16AA difference in Chickens
50AA difference in Yeast
Insulin
Bio 130 Human Biology
/
biogeography
Fig 22.7
Bio 130 Human Biology
Life Evolved on the Earth
about 3.8 Billion Years Ago



Small organic molecules joined to form larger
molecules
Genetic material originated
Organic molecules aggregated into droplets
Bio 130 Human Biology
Major Milesones
in evolution,
starting with
chemistry and
ending with more
recognizable
things
Photosynthesis and
Oxygen atmosphere
Multicellular organisms are
1.3 billion years old
Aerobic metabolism
How do we arrange life?
Making an evolutionary tree
A phylogenetic tree
Sim to fig 22.11
Human evolution
We are a class of organisms called Mammals (Mammalia)
(120mya)
Mammals are vertebrates

Phylum (550 MYA)



Nerve cord
Vertebrae (backbone)
Brain
Bio 130 Human Biology
Mammals




Hair
Long infancy
(comparatively)
Flexibility in responses
due to large brain
Produce milk
(mammary glands)
Bio 130 Human Biology
How biologist classify man
Bio 130 Human Biology
Primates

Monkeys & Apes Physically and
Biochemically similar
Bio 130 Human Biology
Hominoids:

Chimps and Man

Common ancestor about 4-5 million years ago
Bio 130 Human Biology
Bio 130 Human Biology
Evolutionary Trends from
primate to human





Upright walking
Precision and Power grip
Daytime color vision w/ depth perception
More generalized teeth for omnivore diet
Increase in brain size allows for new and
abstract behavior
Bio 130 Human Biology
Another way to list the family
tree of primates
hominoids
Bio 130 Human Biology
Origins of primates





60 mya- nighttime omnivores
40mya Daytime larger brains
35mya ancestor to monkeys and apes and
humans
25mya hominoids
Humans and our like are hominid’s
Bio 130 Human Biology
Bio 130 Human Biology
Humans

Roughly 100,000 years old (from H. erectus)
15,000 years in the Americas
35,000 years in Asia decline of Neanderthal

2 modes




Multiregional hypothesis (humans from
independent evolution in Europe, Asia, Africa and
Australia
Out of Africa, one ancestor
Bio 130 Human Biology
We are evolving now

Our evolution is cultural not morphological
Bio 130 Human Biology
0
Millions of years ago
10
Hominid
Hominoids
20
30
Primates
40
50
Common primate ancestor
60
Figure 22.11
Bio 130 Human Biology
Differences Within the Human
Species


Racial differences are slight differences in
phenotypes between subgroups of a common
species
Differences helped populations adapt to
environments



Dark skin: provides protection from ultraviolet
(UV) damage in intense sunlight
Light skin: allows adequate UV radiation for
vitamin D production in less intense sunlight
Racial differences are no more significant
than individual differences
Figure 22.16



Is natural selection always natural?
What effect does Mass extinction have?
What effect will global travel and
communication have on our phenotypic and
cultural differences?
Bio 130 Human Biology