2. 5.1 Evidence for Evolution
• Evolution – cumulative change in the
heritable characteristics of a
population.
• Changes must be passed on genetically
• Usually takes a long period of time
• One change is not enough to make major
impact
• Does not affect just one individual
Evolution
3. Fossil Record
• Sedimentary Rock
• As layers are put down the inorganic
components of:
• Plants
• Animals
• Bacteria
are preserved.
• Older the rock layers ----- older the
fossil
4.
5.
6.
7.
8. Selective Breeding
• Darwin - humans select desirable traits in
domesticated animals.
• Artificial Selection – foundation of selective
breeding in Plants and Animals.
• Mating of organisms with favorable traits.
Eliminating traits with negative characteristics
• May affect other characteristics
• Furthers variation of species
9.
10.
11. Homologous Structures
• Homologous – similar
• Similar characteristics seen in organisms
that evolved from a common ancestor
• Divergent Evolution
• Seen in organisms over wide geographical
ranges
• Adaptive Radiation – single species
gives rise to several (or many) related
species
• Finches of Galapagos Islands
15. Analogous Structures
• Similar structure and function BUT….
NO COMMON ANCESTOR
• Convergent Evolution - characteristics
becomes more similar as they evolve and
adapt to similar environments.
16.
17.
18. 5.2 - Theory of Evolution by Natural Selection
Charles Darwin
• NATURAL
SELECTION
Alfred Wallace
• INTELLIGENT
EVOLUTION
19. Natural Selection – Five Parts
Be ready to explain the following:
1. Populations tend to produce more offspring than the
environment can support.
2. There will be a struggle for survival.
3. Variation will exist among the offspring produced.
4. Natural Selection will favor the offspring that:
I. Possess the best traits
II. Are most “Fit”
III. Surviving members will reproduce and pass on fit traits.
5. Over many generations…gene pool changes
21. Variations - Random Mutation
• Permanent change in the nucleotide
sequence of the genome.
• 7 different types….frame -shift, deletion,
insertion…..
Random Mutation occur during:
i. DNA Replication
ii. Viral Infection
DOES NOT OCCUR VERY OFTEN!
23. Variations - Sex Cell Production
Meiosis:
Crossing Over
• Occurs during Prophase I
• Creates New combination of
alleles
• Genetic Recombination
Independent Assortment
• Random
• Alleles sort independently
during Metaphase I
24. Variations - Sexual Reproduction
Fertilization
• Alleles from Male and Female combine
• Larger the number of chromosomes greater the variety
• HUMANS – appx. 8,400,000
25. Required Examples of Natural
Selection
•Melanistic Insects(transient polymorphism)
•Beaks of Finches on Daphne
Major(adaptive radiation)
•Antibiotic Resistance
26. Melanistic Insects
• Peppered Moth (Biston betularia)
• Selection Pressure: Predation by Birds
• Variation:
White (typica) Before Black(carbonaria) After
Environmental change – sooty pollution from factories
Result – typica stands out. More carbonaria survive.
Has reversed with clean air policies!
28. Beaks of Finches
• Galapagos Islands – 14 islands, off coast of
Ecuador
• Unknown as to how finches arrived.
• Selection Pressure: increased competition for food
• Variation: different beak shapes and sizes to consume
different food sources. (03-04 – more smaller beaks)
• Environmental change: drought (2003-04). Small seeds
available; large seeds in shorter supply.
• Adaptive radiation
• Speciation
29. Antibiotic Resistance
Bacteria:
• Short life cycle. Can reproduce quickly.
• Why are they resistant? How does resistance occur?
• Mutation
• Plasmid transfer
32. 5.3 – Classification and Biodiversity
• Carl Linnaeus (1735)
Binomial Nomenclature – two-name system; universal
system
• Homo sapiens - human
• Canis familiaris - dog
• Zea mays - corn
Remember – ALWAYS CAPTIALIZE FIRST NAME
33. Hierarchy of Taxa
• Taxonomy – study of classification
•Domain System – 3 domains
1. Eubacteria
2. Archaea
3. Eukaryote
34. Principle Taxa
Taxa are organized from INCLUSIVE to EXCLUSIVE:
DOMAIN
KINGDOM
PHYLUM
CLASS
ORDER
FAMILY
GENUS
species
Taxonomists - can reclassify if evidence warrants
35. Hierarchy of Classification
animal
Domain - Eukarya
Kingdom – Animal
Phylum - Chordata
Class – Mammalia
Order - Primate
Family - Hominidae
Genus - Homo
Species - sapiens
plant
Domain - Eukarya
Kingdom - Plantea
Phylum - Magnoliophyta
Class - Lilopsida
Order - Poales
Family - Poaceae
Genus - Zea
species - mays
36. Some Final thoughts….
• As technology improves several species have been
reclassified for a variety of reasons.
• Artificial Classification –uses arbitrary characteristics to
classify
• Natural Classification – uses ancestry
• Tries to make sense of an organisms place in the world
• Shows evolutionary links
• Predicts characteristics shared by members of a group
48. Dichotomous Keys
Used to identify
organisms based on
structures and features
that organisms possess
•Each level contains two
statements
49.
50. 5.4 - Cladisitics
• Clade – a complete group of
members who have evolved from a
common ancestor.*
• Cladogram – a branching
representation of clades that show
evolutionary relationships.*
• Phylogeny – system of classifying
organisms based on evolutionary
origins and changes over
time.(phylogenic tree)*
53. Formation of Clades
What evidence must be obtained to assign a species to a
clade?
1. ALL ORGANISMS PRODUCE DNA.
2. ALL ORGANISMS PRODUCE PROTEINS FROM THE
SAME 20 AMINO ACIDS CODED FOR IN SEQUENCS
BY DNA.
3. CLOSER THE PROTEIN STRUCTURE…CLOSELY
RELATED
USE A COMMON PROTEIN (cytochrome c)
4. CHANGES IN PROTEINS IN
SPECIES….EVOLUTIONARY CLOCK
Suggests common ancestry for ALL living organisms.
54.
55.
56. Amino Acid Sequence of Cytochrome c
Organism # of a.a. that differ from Humans
Yeast 42
Wheat germ 37
Fruit fly 24
Bullfrog 20
Pigeon 12
Cow 10
Rabbit 9
Rhesus monkey 1
Chimpanzee 0
59. Constructing Cladograms
• These two cladograms are identical (although they don’t look it)
• The shape and the order of the terminal nodes does not matter.
• The only information to be gathered from the cladograms below is the
order of nesting of sister clades and the relative relatedness of
species
60. Human HumanChimp ChimpGorilla Gorilla
Root
Terminal nodes Sister clades: have a
common ancestor
Out group: Defines
the ancestral
characters
Nodes:
Common ancestors
63. Characters Shark Frog Kangaroo Human
Vertebrae X X X X
Two pairs of
limbs
X X X
Mammary glands X X
Placenta X
1. Compile a table of the characters being
compared.
Modified from:
http://www.bu.edu/gk12/eric/cladogram.pdf
65. Shark Frog Kangaroo Human
Mammary Glands
Lungs
Vertebra
e
Placenta
3) Convert the Venn diagram into a
cladogram
66. Analyze cladograms in terms of phylogenetic relationships
1
2
3
DCBA
Of the three nodes,
3 is most recent and 1
occurred earliest.
Node 3 is the most recent
common ancestor for C and D
Node 2 is the most recent common
ancestor for B and C
Node 3 is the common ancestor of all taxa
And so on…
Notes de l'éditeur
Example of adaptive radiation observed by Darwin finches in the Galapagos Islands (nicknamed Darwin's finches). Darwin speculated that the common ancestor of all existing species of Galapagos finches is a seed-eating finch nesting ground. This finch has probably given rise to two lineages, one of finches nesting ground, the other finches tree. The first line has diversified into six seed-eating species and the second in seven insectivorous species and seed-eating species. Here we see a female of each species.
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