Chapters

1
Evolution

• Chapters

2
Intro to Evolution
3
Evolution

• the process of cumulative change in the
  heritable characteristics of a population

4
Players in Evolution

• Jean Baptiste de Lamarck (1744-1829)
• Russel Wallace (1823-1913) and Charles Darwin
  (1809-1882)

5
Natural Selection

• A process in nature in which organisms possessing
  certain genotypic characteristics that make them
  better adjusted to an environment tend to
  survive, reproduce, increase in number or
  frequency, and therefore, are able to transmit
  and perpetuate their essential genotypic
  qualities to succeeding generations.

6
Evidence for Natural Selection

• Fossil Records
• Artificial Selection
• Homologous Structures

7
Mechanisms of Evolution

• Too many offspring
• over production of offspring leads to
  intra-species competition and survival of the
  individuals best suited to that particular
  environment.
• competition can also lead to adaptive behaviours.
• Natural Variation in a Population 
• random assortment of chromosomes
• crossing over of segments of chromosomes result
  in new combinations of genes, different than the
  parental combinations
• random fusion of gametes in sexual reproduction
• additional variations arise due to mutations,
  either chromosomal or gene

8
Natural Selection Summarized

• The favourable characteristics are expressed in
  the phenotypes of some of the offspring
• These offspring may be better able to survive and
  reproduce in a particular environment others
  will be less able to compete successfully to
  survive and reproduce.
• Examples
• Antibiotic Resistant Bacteria
• Peppered Moth
• Heavy Metal Tolerance in Plants

9
Evolution and the Origin of Life
10
Introduction

• Biologists believe that organic evolution by
  natural selection accounts for the major steps in
  evolution.
• macroevolution major developments such as the
  origin of the eukaryotic cell, the origin of
  multicellular organisms, and the origin of
  vertebrates from non-vertebrates
• microevolution the relatively minor changes
  that arise and lead to the appearance of new, but
  closely related species.
• Theory of evolution - the Big Bang.

11
Four Processes for the Spontaneous Origin of Life

• Chemical Reactions to produce simple organic
  molecules, from inorganic molecules
• Assembly of the molecules into polymers
• Self Replication of Polymers
• Development of Membranes to enclose the polymer

12
Chemical Reactions to Produce Simple Organic
Molecules

• Heat, Temperature and Lightning Miller and Urey
  Experiment
• Recreated ancient atmosphere (nitrogen, water
  vapour and carbon dioxide, smaller amounts of
  methane, ammonia, carbon monoxide, sulphur
  dioxide, hydrogen sulphide and hydrogen cyanide.
• Lightning and UV radiation to provide energy

13
Chemical Reactions to Produce Simple Organic
Molecules

• Other Possibilities
• In Space Panspermia
• Alternating Wet and Dry Environments
• Near Volcanos
• Deep Sea and Ocean Vents

14
Formation of Polymers and Self-replication - RNA

• As the organic compounds are made, they arrange
  themselves in lines polymers (Using the Clay
  Lattice as a template)
• Lines of molecules form early enzymes (ribozymes)
• Catalyse reactions, such as peptide bond
  formation
• RNA strand is made and due to enzymes, a
  complementary strand can be made, and then copies
  are made
• Longer and longer double stranded pieces are
  made, forming , now DNA
• DNA more useful as it is longer and can hold more
  information (RNA 1500 nucleotides max)

15
Development of Membranes - Protobionts

• Membranes were needed to separate the external
  environment from the internal environment
• Phospholipids would have formed and due to
  hydophilic and hydrophobic properties, would form
  spheres in water (called coacervate)
• Due to the bilayers, an internal environment
  would form, and if the early molecules (RNA to
  DNA) were trapped in the membrane, protobionts
  would have formed

16
Prokaryotes and the Oxygen on the Atmosphere

• Early cells were anaerobic and heterotrophs
• As nutrients decreased in amount, some evolved to
  become chemoautotrophic, using the gases in the
  air
• Since there was a large amount of CO2, some early
  prokaryotes used the gas, to produce early
  carbohydrate. The waste product was O2, which
  went into the atmosphere

17
Prokaryotes and the Oxygen on the Atmosphere
(continued)

• The formation of an ozone layer in the upper
  atmosphere commenced
• The ozone layer began to reduce the incidence of
  UV light reaching the Earths surface.
• Terrestrial existence (rather than life
  restricted to below the water surface) became a
  possibility
• Other prokaryotes, simply fed on the organic
  molecules available in their environment.
• The bacteria had evolved aerobic respiration and
  so had the enzymes not only of glycolysis, but
  also of the Krebs cycle and terminal oxidation.

18
Endosymbiotic Theory
19
Species and Speciation
20
Definitions Neo - Darwinism

• Gene Pool all of the genetic information
  present in the reproducing members of a
  population at a given time
• Allele Frequency is a measure of the proportion
  of a specific variation of a gene in a
  population.
• The allele frequency is expressed as a proportion
  or a percent, and can be calculated by the
  Hardy-Weinberg equation (more later).
• For example, it is possible that a certain
  allele if present in 25 of the chromosomes
  studied in a population. One quarter of the loci
  for that gene are occupied by that allele. Keep
  in mind it is not the same as the number of
  people who show a particular trait.

21
Evolution Change in Allele Frequency
22
Species and Speciation

• Species
• Morphological Definition
• A type of organism that has fixed characteristics
  that distinguish it from all other species
• Biological Definition
• Group of actually or potentially interbreeding
  populations, with a common gene pool, which are
  reproductively isolated from other such groups

23
Species and Speciation

• Speciation
• the evolution of new species, requires that
  allele frequencies change with time in
  populations.
• Mechanisms Isolation
• Geographic (Allopatric)
• Temporal (Sympatric)
• Behavioral (Sympatric)

24
Species and Speciation (Animation)

• Geographical Isolation (Allopatric)
• Ex. Galapagos Islands
• Ex. Snails
• Lizards

25
Species and Speciation

• Temporal (Sympatric)
• Ex. Plants and Apple Maggot Fly
• Behavioral (Sympatric)
• Ex. Konrad Lorenz and the Gwan
• Movie
• Hybrid Infertility

26
Species and Speciation Trends in Evolution

• Adaptive Radiation
• many similar but distinctive species evolve
  relatively rapidly from a single species or from
  a small number of species.

27
Species and Speciation Trends in Evolution

• When the species evolves different ways, this is
  called DIVERGENT EVOLUTION
• The new species is different than the first, in
  terms of the adaptations that have taken place

28
Species and Speciation Trends in Evolution

• Living organisms often find the same solution to
  particular physiological problems, and as a
  result the organisms, in response to their
  environment, can become morphologically similar,
  even though they are not related to a common
  ancestor.
• This is called CONVERGENT EVOLUTION

29
Species and Speciation Rates of Evolution

• Gradualism

• Punctuated Equilibrium

30
Species and Speciation

• Transient Polymorphisms
• When there are two alleles for a gene in the gene
  pool, it is called polymorphic.
• If one allele is gradually replacing the other,
  based upon environmental pressures, this is
  called balanced polymorphism
• Ex. Peppered Moth (Biston betularia)

31
Species and Speciation

• Balanced Polymorphism
• When two alleles of a gene can persist
  indefinitely in the gene pool of a population
• Ex. Sickle Cell Anemia
• HbN HbN normal
• Hbn Hbn - Sickle Cell anemic but immune to
  malaria
• HbN Hbn heterozygous, slight anemia, but
  resistant to malaria

32
Human Evolution and Origins
33
Human Evolution

• Humans are known as Homo sapiens (modern man).
  The full classification is
• Kingdom Animalia
• Phylum Chordata
• Subphylum Vertebrata
• Class Mammalia
• Subclass Eutheria
• Order Primates
• Suborder Anthropoids
• Family Hominidae
• Genus Homo
• Species Sapiens

34
Human Evolution

• Use Fossil Records as evidence
• Use Carbon 14 Dating to see how old the fossil
  or artefact is.
• For C14, the half-life is 5730 years.
• For fossils and rocks older than 60 000 years, we
  use K40 dating.

35
Human Evolution Humans as Primates

• What defines humans as primates?
• Opposable Thumbs for grasping
• Mobile arms with shoulder joints allowing
  movement in three planes and the bones of the
  shoulder allowing force to be applied to the
  arms.
• Stereoscopic vision
• Skull Modified for upright posture Magnum
  foramen

36
Trends in Hominid Fossils

• Ardipithecus ramidus
• Lived approximately 5.8 4.4 mya in Ethiopia

37
Trends in Hominid Fossils

• Australopithecines
• A. afarensis from the Afar desert (4-2.8 mya)
• A. africanus (3-2 mya) found in South Africa.
• A. robustus (2-1.4 mya) in South Africa.

38
Trends in Hominid Fossils

• A. Africanus

39
Trends in Hominid Fossils

• Homo genus.
• They were from around 2 mya and had larger brains
  (600 cm3) and walked upright.
• H. habilis (handy man). thought he arose from A.
  afarensis 2 mya in East Africa and used simple
  tools.
• Homo erectus was from Africa. It is thought it
  migrated to other parts of the world and had a
  larger brain than H. habilis.
• H. neanderthalensis, which lived in Eurasia from
  200 000 to 30 000 years ago
• Next was H. sapiens, which came to Europe.

40
Trends in Hominid Fossils

• H. Habilis

41
Trends in Hominid Fossils

• H. Erectus

42
Trends in Hominid Fossils

• H. Neadrathalis

43
Trends in Hominid Fossils
44
Trends in Hominid Development

• Hominid Diets and Brain Size
• Australopithecus brains were only slightly larger
  in relation to body size than the brains of apes.
• Powerful jaws meant a largely vegetarian diet.
• 2.5 mya, Africa became drier, led to an evolution
  for survival, as there were less plants
• Tools to hunt, increased supply of protein
  correspond to the changes in brain size

45
Trends in Hominid Development

• Hominid Diets and Brain Size
• The correlation between the change in diet and
  the increases in brain size can be explained in
  two ways
• 1. Eating meat increases the supply of protein,
  fat and energy in the diet, making it possible
  for the growth of larger brains
• 2. Catching and killing prey on the savannas is
  more difficult than gathering plant foods, so
  natural selection will have favoured hominids
  with larger brains and greater intelligence.

46
Trends in Hominid Development

• Genetic and Cultural Evolution
• In the recent evolution of humans, cultural
  evolution has been very important and has been
  responsible for most of the changes in the lives
  of humans over the last few thousand years.
• This is much too short a period for genetic
  evolution to cause much change.
• Some aspects of cultural evolution, ex. Medicine,
  have reduced natural selection between different
  genetic types and therefore, genetic evolution.

47
Taxonomy and Classification
48
Classification and the Binomial System

• Classification
• The process of classification involves giving
  every organism an agreed name and arranging
  organisms into groupings of apparently related
  organisms.
• Scheme of the overall diversity of living things.
  
• Classification attempts to reflect evolutionary
  links.

49
Classification and the Binomial System

• The Binomial System
• Carolus Linnaeus in the 18th Century
• The first part of the name is the genus or the
  generic name based upon a noun.
• The second name is the species, or the specific
  name, based upon an adjective.
• Ex. Canis lupis dog / wolf and grey /brindled
  coat

50
Classification and the Binomial System

• Scheme of Classification
• Kingdom largest and most inclusive grouping
• Phylum / division organisms constructed on a
  similar plan
• Class a grouping of orders within a phylum
• Order a group of apparently related families
• Family- a group of apparently related genera
• Genus - a group of similar and closely related
  species
• Species a group of organisms capable of
  interbreeding to produce fertile offspring

51
Classification and the Binomial System

• Kingdoms
• Prokaryotes Examples are bacteria and
  cyanobacteria
•  
• Protista Examples are Euglena and Paramecium
•  
• Fungi Examples are yeasts and mushrooms.
•  
• Plantae Examples are mosses, ferns, flowering
  plants.
•  
• Animalia - Examples are humans and jellyfish.

52
Classification and the Binomial System

• Plantae Phyla
• Bryophytes (mosses, liverworts)
•  
• Filicinophyta (ferns and horsetails)
• Coniferophyta (cedars, junipers, fir, pine trees)
• Angiospermophyta

53
Classification and the Binomial System

• Animalia Phyla
• Porifera (sponges)
• Cnidaria (corals, sea anemones, jellyfish, sea
  jellies, hydra)
• Platyhelminthes (flatworms)
• Annelida (earthworms, leeches and polychaetes)
• Mollusca (snails, clams, and octopi)
• Arthropoda (insects, spiders, scorpions, and
  crustaceans (crabs, shrimp))

54
Classification and the Binomial System

• Dichotomous Key

55
Mathematics of Population at EquilibriumHardy-We
inberg Principle
56
Hardy-Weinberg Principle

• A mathematical formula to detect change or
  constancy in gene pools
•  The formula
• For 2 alleles of a gene
• Use B for dominant, and its frequency in the
  population is p (a number between 0 1)
• Use b for recessive, and its frequency in the
  population is q (a number between 0 1)
• A gene must have an allele, with the options
  either B or b. No other options are available,
  so if B is present, it frequency is 1, and b is
  0, therefore p q 1 (10)
• Each gene has two alleles, so if the frequency of
  B is p, then BB is p2
• If the frequency of b is q, then bb is q2
• If you have Bb, the frequency is 2pq

57
Hardy-Weinberg Principle

• Since genotypes must be one of the three, the
  percentage in a population will be
• p2 2pq q2 1
•  
• In order to be used, the following conditions
  need to be observed.
• Large population
• Random mating occurs
• No directional selection (no advantage)
• No allele specific mortality
• No mutations
• No immigration or emigration

58
Hardy-Weinberg Principle
59
Phylogeny and Systematics
60
Phylogeny and Systematics

• One of the objectives of classification is to
  represent how living and extinct organisms are
  connected, which means natural classification.
• Phylogeny
• is the study of the evolutionary past of a
  species.
• Species which are the most similar are most
  likely to be closely related
• Species which show a higher degree of difference
  are considered less likely to be closely related.

61
Phylogeny and Systematics

• Values to classifying this way.
• Identify unknown organisms, as other similar
  organisms are grouped together using a key.
• We can see how organisms are related in and
  evolutionary way. By looking at organisms, which
  have similar anatomical features, it is possible
  to see relationships on their phylogenetic tree.
  DNA evidence confirms the anatomical evidence for
  placing organisms in the same group.
• It allows for the prediction of characteristics
  shared by members of a group.

62
Phylogeny and Systematics

• Biochemical Evidence for Common Anscestry
• Every known living organism on Earth uses DNA as
  its main source of genetic information
• All the proteins found in living organisms use
  the same 20 amino acids to forms their
  polypeptide chains
• All the living organisms on Earth have
  left-handed amino acids and none are
  right-handed, leading to the belief that there is
  a common ancestor.

63
Phylogeny and Systematics

• If we compare the amino acid sequences of
  haemoglobin in humans, cats and earthworms, we
  see that cats and humans have greater
  similarities that humans and earthworms.
• This shows several trends
• The more similar the biochemical evidence, the
  more interrelated the species are
• The more similar the evidence, there is less time
  since the two species had a common ancestor (ie.
  The ancestor of earthworms lived a longer time
  ago than the ancestor of cats and human.)
• Changes in the DNA sequences of genes from one
  generation to another are partly due to mutations
  and the more differences there are between two
  species, the les closely related they are.

64
Phylogeny and Systematics

• AAAATTTTCCCCGGGG
• AAAATTTACCCCGGGG
• AAAATTTACCCGCGGG
• AACATCTTCCACGCTG

1 and 2 have the fewest differences in their DNA
and are more closely related
65
Phylogeny and Systematics

• Cladogram

66
Phylogeny and Systematics

• Cladistics
• Clades
• Need to classify, taking into account
• Homologous Characteristics
• Analogous Characteristics

67
Phylogeny and Systematics
68
Phylogeny and Systematics - Dinosaur

• Birds

• Reptiles

• Fused clavicle (wishbone)
• Flexible wrists
• Hollow bones
• Characteristic egg shell
• Hip and leg structure, notably with backward
  pointed knees

• Shoulder girdle
• Strong skeletal system
• Lay eggs
• Lateral leg and hip structure