This document summarizes key concepts related to evolution and biodiversity. It discusses evidence for evolution such as the fossil record and homologous/analogous structures. It also describes Charles Darwin's theory of evolution by natural selection, focusing on how natural selection acts on phenotypic variation in populations to change the gene pool over generations. Finally, it discusses modern classification systems and how cladistics is used to construct phylogenies based on shared derived characteristics.

1. Evolution and Biodiversity
IB TOPIC 5

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

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

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

12. Darwin’s Finches

13. Pentadactyl Limbs

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.

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

20. Struggle for Survival
•Competition for Food
•Predation
•Parasitism
•Disease
•Competition for Mates
•Competition for Living Space

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!

22. Deletion

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!

27. Beaks of Finches

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

30. Antibiotic Resistance
• Bacteria – Staphylococcus aureus
• Antibiotic: Methycillin (selection pressure – addition of)
• Variation
I. Methycillin Resistant (MRSA)
II. Methycillin Suseptible (MSSA)
Environmental change: addition of methycillin
Result: MSSA killed, MRSA survives – increases &
dominates
Methycillin no longer effective

31. MRSA

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

37. Bryophyta

38. Fillicinophyta

39. Coniferophyta

40. Angiospermophyta

41. Porifera

42. Radial vs. Bilateral
• Radial – circular with
one center point. (pie)
• Bilateral – can be
divided into “mirror”
halves through a
single plane

43. Cnidaria

44. Platyhelminthes and Annelid
Platyhelminthes
Annelid

45. Mollusca

46. Arthropod

47. Chordata

48. Dichotomous Keys
Used to identify
organisms based on
structures and features
that organisms possess
•Each level contains two
statements

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)*

51. Phylogenic Trees

52. Characteristics for Classification
1.Morphology
2.Anatomy
3.Cytology
4.Photochemistry
5.Chromosome numbers
6.Molecular differences

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.

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

57. Vertebrate
Hai
r
Shelle
d eggs
Amniotic Egg
Four
Limbs
Bony
Skeleton
Each clade
is determined by
common
characteristics
of its members that are
different from that of
the other species from
which it has diverged

58. Homologous vs. Analogous
REMEMBER:
HOMOLOGOUS – inherited from a common ancestor
ANALOGOUS - do not stem from a common ancestor.
Bats – Birds – Bugs > >>>>>WINGS

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

61. Thisis acomputergeneratedcladogramfor bacteria.

62. Building Cladograms

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

64. Vertebrae:
Shark
Two Pairs
of Limbs:
Frog
Mammary
Glands:
Kangaroo
Placenta:
Human
2) Use the data to
construct a Venn diagram,
Start with the
characteristic
shared by all
taxa in the
biggest circle
and work
inwards

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…