This document discusses key concepts in biological evolution and taxonomy. It defines natural theology as the study of nature to understand the creator's plan. It describes the work of Carolus Linnaeus in establishing taxonomy and Jean Baptiste Lamarck's comparison of current and fossil species. The document then covers Darwin and Wallace's theory of descent with modification through natural selection and genetic inheritance. It discusses populations, species, and mechanisms of evolution like genetic drift, mutation, gene flow and natural selection. Finally, it summarizes population genetics, speciation, phylogeny, cladistics, and allopatric versus sympatric speciation.

1. JJA Obico, Instructor, Department of Biology

2. Natural TheologyNatural Theology
Philosophy dedicated top y
discovering the Creator’s plan by
studying nature
Classify species in order to reveal
the steps of life that God had
createdcreated
Carolus Linnaeus
- sought to discover order in the
diversity of life
- founder of Taxonomy- founder of Taxonomy

3. Jean Baptiste LamarckJean Baptiste Lamarck
In-charge of invertebrate
collection at the Natural History
Museum in Paris
Compared current species to
fossil formsfossil forms
Use and DisuseUse and Disuse
Inheritance of Acquired
Characteristics

5. Biological EvolutionBiological Evolution
Descent with modification
Charles Darwin and Alfred WallaceCharles Darwin and Alfred Wallace
Descent
- Transfer of genetic material to offspring overtimeg p g
a. Clonal reproduction (asexual)
b. Sexual reproduction

6. Biological EvolutionBiological Evolution
ModificationModification
- Change in genetic material
Mutation; genetic- Mutation; genetic
recombination

8. What evolves?What evolves?
Populationp
- A group of individuals of the same species
usually geographically delimited and
i ll h i ifi ftypically have a significant amount of gene
exchange
Species
- Consists of group generally intergrading- Consists of group generally intergrading,
interbreeding populations that are
reproductively isolated from other groups

9. Mechanisms of EvolutionMechanisms of Evolution
Genetic DriftGenetic Drift
Mutation
Gene flowGene flow
Non random mating
Natural Selection

10. Population Genetics (PopGen)Population Genetics (PopGen)
Study of behavior of genes in theStudy of behavior of genes in the
population
Genetics + EvolutionGenetics + Evolution
Mendel (1866); Darwin and Wallace
(1858)(1858)

11. Population GeneticsPopulation Genetics
Evolution
- A change in the frequency of alleles in a
population over time
1000 garden peas; 2000 alleles (TT, Tt or tt)
T= 1000; t= 1000 freq of each allele= 0.5
What happens when
T i d ?a. T inc; t dec?
b. T dec; t inc?
F d t hc. Freq does not change

12. Hardy-Weinberg EquilibriumHardy Weinberg Equilibrium
Frequency of alleles will remain the sameFrequency of alleles will remain the same
under the following conditions:
1 Size of population is large1. Size of population is large
2. No mutations
3 N i ti3. No migrations
4. Mating is random
5. Natural selection does not take place

13. Genetic DriftGenetic Drift
- Change of frequency of alleles over timeChange of frequency of alleles over time
due to chance
a. Bottleneck effect
- occurs when a catastrophic event
drastically and nonselectively reduces
size of population
b. Founder effect
- small no. of individuals colonize a new
area

16. MutationsMutations
Alter the nucleotide sequence of genesAlter the nucleotide sequence of genes
May give an selective advantage in a
particular environmentparticular environment
eg. Tolerance to a toxic metal

17. Gene FlowGene Flow
Movement of alleles form one populationMovement of alleles form one population
to another
Pollen seeds fruitsPollen, seeds, fruits
Runners or horizontal stems

18. Mating is randomMating is random
Individuals mate without regard toIndividuals mate without regard to
genotype
Nonrandom matingNonrandom mating
- Self fertilization
A t ti ti t f- Assortative mating- outcome of
pollinator preference
H k th f t f d fleg. Hawkmoths prefer to feed on flowers
with long corolla tube

19. Natural selectionNatural selection
Thomas MalthusThomas Malthus
- Population of organisms tend to
increase geometricallyincrease geometrically
- Geometric progression:
2 4 8 16 32 642,4,8,16,32,64…
- Resources are limited

20. Individual variation within
species
MutationMutation
Crossing over
RecombinationRecombination
Transposons
- DNA sequences
- have the ability to move from place to
place in chromosomes

23. Natural selectionNatural selection
Individuals that are best adapted to theirIndividuals that are best adapted to their
environment have the greatest chance
of surviving and successfullyg y
reproducing

25. Certain traits that are common amongCertain traits that are common among
individuals
- provide superior adaptation in- provide superior adaptation in
environment
Less common traits- do not conferLess common traits- do not confer
selective advantage

26. Tropical ForestsTropical Forests
Lack of windLack of wind
Low light intensity
Plants
- Undivided leaves, large, with acumen

28. Competition for resources is NOTCompetition for resources is NOT
necessary for natural selection to occur
Natural selection may occur if certainNatural selection may occur if certain
individuals produce more offspring than
othersothers

30. Modes of natural selectionModes of natural selection
Stabilizing selection
- eliminates extreme phenotypesp yp
Directional selection
shifts the average or typical in one direction- shifts the average or typical in one direction
by favoring one of the extreme phenotypes
- leads to ANAGENESIS or phyletic evolution
Diversifying selection
- splits a population into 2 parts favoring both- splits a population into 2 parts favoring both
extremes of phenotypic range
- leads to CLADOGENESIS or branching
evolutionevolution

32. Artificial selectionArtificial selection
Selectively breeding plants or animals toSelectively breeding plants or animals to
favor the production of offspring with
desirable traits

33. Evolution can occur rapidlyEvolution can occur rapidly
Punctuated equilibriumPunctuated equilibrium
Eldredge and Gould, 1972
punctuated with short periods of rapidpunctuated with short periods of rapid
change
F th d fFew year or thousand of years
eg.
-Colonization of mine tailings by plants

34. Co-evolutionCo evolution
a change in the genetica change in the genetic
composition of one species in
response to a genetic changep g g
in another
Plants and insectsPlants and insects

35. SpeciationSpeciation
Formation of new species from preexistingp p g
species
Ultimate result of evolution
Biological Species Concept
A population whose members have the- A population whose members have the
potential to interbreed with one another in
nature to produce viable, fertile offspring but
h t d i bl f til ff iwho cannot produce viable, fertile offspring
with members of other species
- Reproductively isolated from other populationsReproductively isolated from other populations

36. Reproductive isolationReproductive isolation
PrezygoticPrezygotic
- Sperm does not fertilize egg from other
populationpopulation
- No zygote is formed
Postzygotic
- Zygote or embryo does not survive or
adult is infertile

37. PrezygoticPrezygotic
Temporal isolationp
Seasonal
Diurnal
Ecological eg AcerEcological – eg. Acer
black maple (Acer nigrum)- dry, high Ca
sugar maple (A. saccharum)- acidic
Self fertilization
Floral
Behavioral restriction to one pollinatorBehavioral- restriction to one pollinator
Structural – white and red petaled flower
Pollen-pistil incompatibilityp p y

38. Post zygoticPost zygotic
Inviable seed
Hybrid inviability- not reach reproductive
maturity
Hybrid floral isolation – no pollinators
Hybrid sterility
Chromosomes do not pair during meiosis
Brocolli (Brassica oleracea) x radish (Raphanus
sativus) Raphanobrassica) p
Hybrid breakdown- problems in later
generation of hybrids

39. Modes of speciationModes of speciation
Allopatric speciationAllopatric speciation
Geographical barrier that physically isolates
populations hinders gene flowp p g
Sympatric speciation
Intrinsic factors alter gene flowIntrinsic factors alter gene flow

40. Allopatric speciationAllopatric speciation
geographical barriers: mountain rangegeographical barriers: mountain range,
oceans, lakes, creeping glaciers
Adaptive radiationAdaptive radiation
- When a species move into previously
unoccupied environment (island orunoccupied environment (island or
occupied environment with many
opportunities to succeed)opportunities to succeed)
- Scalesia spp. in Galapagos Islands

41. Sympatric SpeciationSympatric Speciation
Occurs within the range of parentOccurs within the range of parent
populations
Polyploidyyp y
- more than 2 complete sets of
chromosomes; common in plants
- oats, cotton, potatoes, tobacco, wheat
a. Autopolyploid- from single species
b. Allopolyploid- 2 different species
- more vigorous than parentsg p

44. What is phylogeny?
Evolutionary history or pattern of descent
What is phylogenetic systematics
(cladistics)?(cladistics)?
Branch of systematics concerned with inferring
phylogenyphylogeny
Lines on cladogram?
Lineage = sequence of ancestral-descendentLineage sequence of ancestral descendent
populations through time; represent descent

45. Split, from one lineage into two?
Divergence, which may lead to speciation
Pre-existing feature?g
Primitive / Ancestral / Plesiomorphic
New feature?New feature?
Advanced / Derived / Apomorphic

46. PheneticPhenetic
- classification based on overall
similaritiessimilarities
- common to everyone
Phylogenetic
classification based on evolutionary- classification based on evolutionary
history or pattern of descent

47. Can be arbitraryCan be arbitrary,
e.g., classify these:

48. Represented in the form of a cladogram/Represented in the form of a cladogram/
phylogenetic tree
CladogramCladogram
• Lines- lineage or clades; denote descent
• Branching- divergence from a common ancestorBranching divergence from a common ancestor
Evolution recognized as a change from
pre-existing character state(ancestral) topre existing character state(ancestral) to
a new (derived) character state

49. All of life is interconnected byAll of life is interconnected by
TAXA
descentdescent
A B C D E F
TIME
lineage
or clade
TIME
Cladogram or Phylogenetic TreeCladogram or Phylogenetic Tree

50. A B C D E F
TAXA
TIME
speciation
Cladogram or Phylogenetic Tree

51. CladisticsCladistics
Methodology of inferring the pattern of
evolutionary history of a group ofevolutionary history of a group of
organisms using apomorphic characters
Ancestral character
Pleisiomorphy- Pleisiomorphy
Derived character
- Apomorphy- Apomorphy

52. Apomorphies the result of evolutionApomorphies - the result of evolution.
Taxa sharing apomorphies underwentTaxa sharing apomorphies underwent
same evolutionary history,
should be grouped togethershould be grouped together.

53. A B C D E F
TAXA
Apomorphies
f B&C
Apomorphy
for taxon D
for taxa B&C
TIME
Apomorphy
for taxa B-F
Cladogram or Phylogenetic Tree

54. Common ancestry
TAXA
A B C D E F
TIME
common ancestor
(of taxon D, E, & F)
Cl d Ph l ti T
common ancestor
(of taxon A & taxa B-F)
Cladogram or Phylogenetic Tree

55. Similarity due to common ancestry- similar DNA sequences
Intraindividual homology?gy
Similarity by common ancestry of features within
an individual e g carpels and leavesan individual, e.g., carpels and leaves
(common ancestry by genes)

56. Similarity not by common ancestry.
Types?
Convergence independent evolution of aConvergence - independent evolution of a
similar feature in 2 or more lineages.
Reversal - loss of a derived feature with re-
establishment of ancestral featureestablishment of ancestral feature.

57. Convergence - Stem succulence and “spines” in
Cactaceae and Euphorbia sppCactaceae and Euphorbia spp.

58. Reversal - Loss of perianth in Lemna, Wolffia.

59. Recognized group in phylogeneticRecognized group in phylogenetic
systematics
Consisting of a common ancestor plus allConsisting of a common ancestor plus all
of its descendants
Sequential listing of monophyletic groupSequential listing of monophyletic group
- serve as a phylogenetic classification
schemescheme

60. A B C D E F
TAXA
monophyletic
group
TIME
t
common ancestor
(of taxon A & taxa B-F)
common ancestor
(of taxon D, E, & F)
Cladogram or Phylogenetic Tree

61. Consisting of a common ancestor but notConsisting of a common ancestor but not
all descendants of that common ancestor
Two or more separate groups each with a
separate common ancestor

62. A B C D E F
TAXA
TIME
common ancestor
(of taxon A & taxa B-F)
common ancestor
(of taxon D, E, & F)
Cladogram or Phylogenetic Tree

63. A B C D E F
TAXA
A B C D E F
TIME
common ancestor
( f t A & t B F)
common ancestor
(of taxon D, E, & F)
Cladogram or Phylogenetic Tree
(of taxon A & taxa B-F)