Download Evolution Notes 14

Lemarck’s Theory
• Organisms develop new organs or change their
structures to meet changes in their environment
(use it or lose it)
• Inheritance of acquired traits – traits acquired
during a lifetime could be passed on to next
generation
FOLLOW
DIRECTIONS!
• Write your name at the bottom
• When you get a paper, draw what you see
as closely as you can on your own paper
– Pass their paper back when you are done with it
• Do NOT trace
• Do not let the people behind you see what
you are copying
• Pay attention and DON’T TALK!
Taxonomy
Grouping of organisms based on
similar characteristics.
Species
Organism that has at least one
characteristic not shared with any
other organism
Characteristics
Controlled by proteins
Proteins
Made of amino acids
Amino Acids
Coded for by a gene
Gene
Set of nitrogen bases in DNA
molecule
Mutation
Change in nitrogen bases through
any number of causes
• Darwin traveled 5 years on
the Beagle as its naturalist
• He sent samples back
• He wrote a 200 page essay
on his observations
• Darwin published his book
entitled
The Origin of Species
• all species reproduce in excess of the
numbers that can survive
• all organisms compete for limited
resources
• variations exist within a species
• environment selects for the more
advantageous variations = better
suited  leave more offspring (fitness)
Video
Darwin’s example of
Natural Selection
Galapagos Island Finches, p.305
– 13 species – closely resemble 1 species
living on South American mainland
– The mainland species strayed and
evolved into 13 different species
• Each island had slightly different conditions
• Best suited (most fit) to environ.  leave
most offspring
– Variation is heritable
– Natural Selection leads to adaptation, which
leads to new species
Conditions determine Characteristics
•Related organisms becomes less alike
• Change in gene frequency / species over time
• Unifying theory of biology based on scientific observation.
Change in a population’s alleles over a period of time
Evolution which gives rise to new species
Needed for evolution to occur
Mutations – changes in nucleotide
sequence of DNA
Recombination – reshuffling of
genetic material during meiosis
Gene flow – gene frequency
changes due to immigration from
other populations
Needed for evolution to occur
Natural selection – organisms with less
advantageous traits (genes) survive less often
Microevolution
Change in a population’s alleles over a period
of time
Macroevolution
Large changes
recorded in the fossil
record (large scale)
Speciation:
When a group of one species is cut off from the
rest of the population and gene flow is stopped.
Each group is acted on by local selective
conditions.
Kiabab Squirrel
Abert Squirrel
Divergent Evolution – two groups of the
same species separate and become less alike
over time
Video
Convergent Evolution –
two unrelated groups of
organisms develop similar
structures based on similar
living conditions
Gradualism
• Evolution in slow gradual steps
Punctuated Equilibrium
• short periods of rapid species formation followed by
long periods of little evolution
Video
Evidence Supporting Evolution
1. Fossil Record, p.299
•
Types/examples of
2. Geographic Distribution, p.300
3. Similarities in Structure, p.301
•
•
Homologous structures
Vestigial structures
4. Similarities in Development
5. Molecular Biology
Any preserved remnant or impression
left by organisms that lived in the past.
Relative dating – superimposition of
sedimentary rocks tells the relative age of
fossils
 Absolute dating – dating using half-lives
of radioactive isotopes (Potassium 40,
Rubidium 87, Uranium 238, Carbon 14)
Transitional forms
– Archeoptryx and
similar bird-like
reptiles.
Absence of some
forms can also be
used as an
argument against
evolution.
Geographic Distribution
Homologous structures Structures that share a common ancestry.
Modified versions of the same structure.
Vestigial structures Remnants of an organisms evolutionary
past. The structure serves no major purpose
at this time.
Developmental Similarities
Embryos start
out looking
very similar
salamander, cow,
pig, tortoise, fish,
chicken, human
rabbit
The longer it takes
into development
to look different,
the more closely
relate the species
DNA comparison
- The longer that species or populations are
separated, the more chance there is for mutations to
cause differences in DNA
Similar DNA = close relative (recent ancestor)
Protein comparison
- Similar to DNA comparison, but
focuses on amino acid sequence in
common proteins