Evolution of Living Systems

1
Evolution of Living Systems

• Introduction
• Power of the theory diversity and similarity of
  life forms
• Theory and a Gift
• Historical context of evolution
• Processes and mechanisms of evolution
• Origin and evolution of life
• Earth
• Astrobiology
• Classification
• Specific topics for discussion
• Viruses
• Evolution of humans
• Evolution in action literally as you sleep

2
Take-Home Messages

• Darwin, Voyage of the Beagle and the Origin of
  Species power of observation coupled with
  intuition
• Natural selection operates on genetic variation
  at the level of populations and over time
  gradually changes the gene pool, leading to
  microevolution (populations) and/or
  macroevolution (species)
• Mechanism of evolution underpins our
  understanding of origin of life of earth,
  evolution and classification of organisms, and
  emerging sense of origin of life forms elsewhere
  in the universe (astrobiology)
• As you sleep, evolution is in action, and
  notable examples are GMOs, pesticide resistance
  in plants and animals, and antibiotic resistance
  in microbes
• Theory of evolution extraordinarily provides the
  mechanism to explain two sides of the same coin
  diversity and similarity of living systems
• Theory of evolution is a gift of monumental
  importance in the life sciences and its
  importance has only grown since Darwins seminal
  publication in 1859

3
Evolution of Living Systems

• Introduction
• Power of the theory diversity and similarity of
  life forms
• Theory and a Gift
• Historical context of evolution
• Processes and mechanisms of evolution
• Origin and evolution of life
• Earth
• Astrobiology
• Classification
• Specific topics for discussion
• Viruses
• Evolution of humans
• Evolution in action literally as you sleep

4
Introduction

• Two sides of the same coin
• Diversity of life forms
• Similarity of life forms (you are a worm)
• Theory of evolution
• What is a theory?
• Define theory of evolution
• Species arise/evolve gradually from ancestral
  species
• Mechanism is natural selection
• Gift to biology
• Unifying theory around which to explain the
  diversity and similarity
• Evolution preserves traits that confer an
  advantage
• Evolution also adopts new traits that confer an
  advantage
• Impressive and substantial underpinning to the
  life sciences (ecology, environmental sciences,
  genetic engineering, astrobiology, etc.)

5
Evolution of Living Systems

• Introduction
• Power of the theory diversity and similarity of
  life forms
• Theory and a Gift
• Historical context of evolution
• Processes and mechanisms of evolution
• Origin and evolution of life
• Earth
• Astrobiology
• Classification
• Specific topics for discussion
• Viruses
• Evolution of humans
• Evolution in action literally as you sleep

6
Historical Context Darwin

• Voyage of the Beagle on the HMS Beagle (1831)
• Age 22 as naturalist to catalogue plants and
  animals (simply observe and document)
• Convention at the time static view
  (pre-ordained)
• Frame of reference for Darwin UK landscape about
  as bland as UK food

7
Notable Observations by Darwin

• South American diversity of landscapes
• Brazilian rainforest
• Grasslands/savannas of Argentina
• Dry deserts of Terra del Fuego (tip)
• Towering mountains of the Andes on west coast
• Flora and fauna distinct from Europe and UK
• Battery of structures (plants and animals) that
  had intuitive value in the environment
  (adaptations)
• Seeding of idea living systems are not
  static/preordained but vary as a function of the
  environment

8
Observations (contd)

• Galapagos Islands (key event to Origin of
  Species)
• Volcanic series of islands of Ecuador and Peru
  (800 km) recent geological origin
• Fauna (birds, tortoises, etc.)
• not observed anywhere else
• Distinct lineage to species on S. American
  mainland (e.g., 13 species of finches)
• Seeding of idea fauna arrived from mainland and
  the diversified

9
Darwin in England (1836)

• Two seminal ideas in 1830s
• Malthus population growth far exceeds available
  resources (all organisms)
• Competition for limited resources (food, water,
  light, mates) limits number of offspring that
  survive (e.g., maple tree produces 1000s of seed
  of which perhaps 10 germinate and grow 0.0001)
• Hypothesis
• Environment drives the origin of species via
  the gradual accumulation of traits that
  steadily improve survival over time (centuries
  to millennia)

10
Darwin and Natural Selection (1840)

• Idea No. 1 Organisms differ in their success in
  reproduction and therefore contribute differently
  to future generations
• Idea No. 2 Driving force for this differential
  success is natural selection that acts on the
  variability among individuals
• Product Evolution of adaptations to enhance
  success (fitness)
• Relate back to the Voyage of the Beagle (1831)

11
Darwin Origin of Species (1859)

• Note elapsed time from first observation (1831)
  to publication (1959)
• Two principal tenets
• Species evolve gradually from ancestral species
• Mechanism is natural selection
• Theory of Evolution as a gift to biology
• Origin of diversity is _____________
• Origin of similarity is _____________
• Consequences for a host of other aspects of the
  life sciences

12
Heads Diversity
13
Tails Similarity at the Molecular Level
14
Evolution of Living Systems

• Introduction
• Power of the theory diversity and similarity of
  life forms
• Theory and a Gift
• Historical context of evolution
• Processes and mechanisms of evolution
• Origin and evolution of life
• Earth
• Astrobiology
• Classification
• Specific topics for discussion
• Viruses
• Evolution of humans
• Evolution in action literally as you sleep

15
Processes and Mechanisms

• Misconception that individuals evolve
• Individuals develop NOT evolve
• Populations and species evolve (key levels of
  hierarchy)
• Kingdom
• Family
• Species
• Populations
• Individuals
• Organs
• Evolution at the population level is called
  microevolution
• Evolution at the species level is called
  macroevolution

16
Concept of Fitness

• Fitness relative contribution of an individual
  to the next generation
• Positive fitness
• Negative fitness
• Contrast fitness to survival of the fittest
• Contrast fitness to struggle for survival
• Example of sexual dimorphism in animals
• Ornate plumage in birds attracts mates
• Ornate plumage also attracts predators
• Positive fitness contribution to the next
  generation

17
Variation in Fitness

• Organisms vary in their morphology, physiology
  and biochemistry
• Without variation, no differential fitness as all
  individuals are the same
• Source of variation is genetics (yet to be
  discovered)
• Inheritance of traits (1860s)
• DNA (1950s)
• Gene sequences (1970s)

18
Summary of Mechanism (1940s)

• Two cardinal foundations of evolution
• Natural selection as presented by Darwin
• Individuals differ genetically in their fitness
• Result gene pool of the next generation is a
  consequence of the action of natural selection on
  inherited variation at the level of populations

19
Selection Fitness Gene Pool Microevolution Macroev
olution
First Generation Gene Pool
Second Generation Gene Pool
N100 Generations Gene Pool
N1000 Generations Gene Pool
20
Speciation
24-511
Figure 24.14
21
Large-Scale Changes Global Selective Agents

• Progressive physical/chemical changes
• Carbon dioxide in the atmosphere
• Oxygen in the atmosphere
• Ultraviolet radiation in the atmosphere
• Breakup of Pangeae
• Climate change today
• Catastrophic physical/chemical climate change
• Asteroid impacts (dinosaurs)
• Instantaneous biological changes
• Evolution of enzymes
• Endosymbiosis and Lynn Margulis

22
Earths Selective Agents in the Atmosphere
24-507
Figure 24.4
23
Large Scale Physical Changes Breakup of Pangeae
19-381b
Figure 19.19b
24
Geographical Isolation and Evolution Darwin and
the Galapagos
19-381a
Figure 19.19a
25
Endosymbiosis Lynn Margulis
24-506
Figure 24.3
26
Evolution of Living Systems

• Introduction
• Power of the theory diversity and similarity of
  life forms
• Theory and a Gift
• Historical context of evolution
• Processes and mechanisms of evolution
• Origin and evolution of life
• Earth
• Astrobiology
• Classification
• Specific topics for discussion
• Viruses
• Evolution of humans
• Evolution in action literally as you sleep

27
Origin and Evolution of Life on Earth
28
Origin of Life in the Universe Astrobiology

• Chemicals of life
• Information brokers nucleic acids and
  nucleotides DNA and RNA
• Carbohydrates (carbon skeletons for polymers)
• Lipids (membranes)
• Proteins (enzymes)
• Medium for life is water (H2O)
• Chemicals for life are common in the Universe and
  environment (temperature) is commonplace
• Probability extremely-extremely high that life
  has originated and evolved elsewhere in the
  Universe at multiple times
• Panspermia hypothesis life on Earth originated
  elsewhere in the Universe and was transported here

29
Panspermia
30
Progression of the Sciences Leading to
Astrobiology
Habitability of Extraterrestrial Systems
Astrobiology
Copernican Revolution
Sun-Centered World
Revolutions in Physics, Chemistry, Geochemistry,
and Life Sciences
Earth-Centered World
31
Origin and Evolution of Life Classification

• Domain Domain
  Domain
• Bacteria Archaea
  Eukarya
• Common Ancestor
• (4 - 4.5 Billion Years Ago)

32
Classification of Life on Earth
33
Evolution of Living Systems

• Introduction
• Power of the theory diversity and similarity of
  life forms
• Theory and a Gift
• Historical context of evolution
• Processes and mechanisms of evolution
• Origin and evolution of life
• Earth
• Astrobiology
• Classification
• Specific topics for discussion
• Viruses
• Evolution of humans
• Evolution in action literally as you sleep

34
Illustration of a virus
24-519
Figure 24.28
35
Viral nucleic acid and a host cell
24-520
Figure 24.29
36
Evolution of Humans
24-514
Figure 24.17
37
Evolution in Action As You Sleep

• Antibiotic resistance in microbes
• 100 antibiotics since 1940s (penicillum)
• Generation time for microbes and intense natural
  selection for resistance
• Industrial melanism in moths
• White versus dark colored moths in UK and
  pollution (selection is predation by birds)
• Herbicide resistance in weeds
• Cockroaches resistant to insecticides
• Genetically Modified Organisms (GMOs)

38
Take-Home Messages

• Darwin, Voyage of the Beagle and the Origin of
  Species power of observation coupled with
  intuition
• Natural selection operates on genetic variation
  at the level of populations and over time
  gradually changes the gene pool, leading to
  microevolution (populations) and/or
  macroevolution (species)
• Mechanism of evolution underpins our
  understanding of origin of life of earth,
  evolution and classification of organisms, and
  emerging sense of origin of life forms elsewhere
  in the universe (astrobiology)
• As you sleep, evolution is in action, and
  notable examples are GMOs, pesticide resistance
  in plants and animals, and antibiotic resistance
  in microbes
• Theory of evolution extraordinarily provides the
  mechanism to explain two sides of the same coin
  diversity and similarity of living systems
• Theory of evolution is a gift of monumental
  importance in the life sciences and its
  importance has only grown since Darwins seminal
  publication in 1859

39
Omissions from Chapter 24

• Classification (pp 640-650)