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Chapter 14: Principles of Evolution. Biogeography Comparative Anatomy “homologous” structures, similar Fossil record – similar structures, carbon dating – evolution Theories of Evolution Catastrophism – large environmental disaster  things change Lamarck’s

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Chapter 14: Principles of Evolution

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Chapter 14:






    • Comparative Anatomy
      • “homologous” structures, similar
      • Fossil record – similar structures, carbon dating – evolution
  • Theories of Evolution
    • Catastrophism – large environmental disaster  things change
    • Lamarck’s
      • Inheritance of acquired – characteristics (organism changed in it’s lifetime – could pass those changes to offspring)

Wallace – “survival of the fittest” evolution

  • Darwin – father of evolution 1858
    • Biological diversity – gene pool – there is always diversity within a species
    • Fitness – traits best suited for survival
    • Natural selection – survival of the fittest, best traits will be passed on
    • Artificial selection – man selected, domestication
    • Adaptation – allows for survival
      • Structural – anatomy
      • Behavioral – courtship, hibernation
      • Physiological – how the body works

Evidence for evolution

    • Radiometric dating – carbon 14 dating, radioactive substances break down in half lives – decay
    • Fossils – imprints of structures within rock
    • Comparative morphology and embryology – development prior to birth
      • Homologous features – similar structures, similar embryological development,
      • Ex. bat and bird wings
      • 2. Analogous features – similar functions develop differently
      • Ex. bat wings and butterfly wings
      • 3. Vestigial structures: present, no longer needed

Experimental evidence –

    • peppered moths, 2 variations white and gray
    • Trees with birch (lighter bark)
    • And lichen – more white moths
    • 1860’s coal  soot killed lichen  trees darken more gray moths
    • 1900’s less soot  lichen back lighter bark- more white moths

Chapter 15:





Change in frequency of alleles – how genetic information changes, which traits show up more often

  • Five agents in microevolution
    • Mutation – change in genetic code, lethal, neutral, beneficial
    • Gene flow – beneficial traits will be passed from generation to generation – one population to another
    • Genetic drift – chance alteration of genes
      • Founder effect – species in new environment will favor certain genes
      • Bottleneck – cheetah – severe reduction in population small population limited gene pool, greater chance for genetic disorders
      • Inbreeding – homozygous limited gene pool, greater chance for genetic disorders

Nonrandom mating(sexual selection) – given member of a population is not equally likely to mate with any other given member “fittest”

  • Natural selection
    • Adaptations – traits best suited for survival are passed on
    • Fitness – best adaptive traits
    • Galapagos finches – Darwin – 13 finches – common ancestor, beak size and shape – and Grant’s study – evolution can quickly occur

Three modes

    • Stabilizing selection – “average” most common
    • Directional selection – “change in the environment” shift to one extreme or the other
    • Disruptive selection – splits population into 2 groups

Chapter 16:






Species – interbreeding populations which produce viable offspring

  • II. Reproductive isolating mechanisms – keeps species separate
    • Prezygotic – prevents sperm from fertilizing egg
      • Mechanical – not physically compatible
      • Behavioral – “behaviors” are different, courtship song displays
      • 3. Temporal – breed at different times
      • 4. Gamete – egg and sperm cannot fuse
      • 5. Ecological – different habitats

B. Postzygotic

    • Hybrids – offspring may not survive or be sterile

III. Mechanisms of speciation

    • Allopatric speciation – “of other countries”
      • 1.species separated by geography change over time Darwin’s finches
    • Colonization – 1 group of finches  13 species new island, the fittest survive
    • Genetic divergence – over time species change due to adapting to new environment
    • Reproductive isolation – gene pool is separated from original gene pool – changes occur over time
    • Competition – fittest for environment survive to breed those characteristics to offspring
    • Further speciation – original species  new species

Sympatric speciation – absence of geologic separation, fruit flies, hawthornes, apples

  • ????Parapatric speciation – next to small population on the fringe of a habitat can form it’s own breeding group

Evolutionary change

  • A. Vestigial structures: present, no longer needed
    • Coevolution –
    • symbiotic relationships “mimicry”
    • C. Comparative biochemistry –
    • chemical makeup, horseshoe crab,
    • blood chemistry same as spiders
    • D. Genetics – DNA
    • V. Extinction: death of the last of a species
    • A. Habitat destruction
    • B. Competition
chapter 18





I. Taxonomy

    • Linnaeus – father of taxonomy, classification system based on homologous structures
    • Binomial nomenclature
      • 2 term naming system
      • Genus species – identification system
      • Homo sapiens, Felis tigris, Felis leo

eastern bluebird (Sialiasialis), the western bluebird (Sialiamexicana), and the mountain bluebird (Sialiacurrucoides)—remain distinct because they do not interbreed.



  • 1. Archaea- ancient bacteria prokaryotes
  • 2. Bacteria- modern bacteria prokaryotes
  • 3. Eukarya- eukaryotes divided into Animal, Plant, Protist and Fungi Kingdoms
    • D. Kingdoms
      • Animal – heterotrophs, multicellular, eukaryote
      • Plant – autotrophs – multicellular, eukaryote
      • Protist – heterotrophs & autotrophs, unicellular, eukaryote
      • Fungi – heterotrophs, plant like, multi cellular, eukaryote
      • Monera – bacteria and viruses, prokaryotes

Taxonomic system Humans

  • 1. Kingdom Animalia
  • 2. Phylum Chordata “notochord”
  • 3. Class Mammalia “hair, mammary glands,
  • give birth to live young
  • 4. Order Primate “binocular vision, opposable thumb”
  • 5. Family Hominidae “walk upright”
  • 6. Genus Homo “man-like”
  • 7. Species sapien modern day
  • E. Taxonomic Key – systematic way to identify organisms using structures
how many species exist
How Many Species Exist?
  • Biodiversity is the total number of species in an ecosystem

Between 7,000 and 10,000 new species are identified annually, mostly in the tropics

Tropical rain forests are believed to be home to two-thirds of the world’s existing species, most of which have yet to be named

Because tropical rain forests are being destroyed so rapidly, species may become extinct before we ever knew they existed


The black-faced lion tamarin

Researchers estimate that no more than 260 individuals remain in the wild; captive breeding may be the black-faced lion tamarin's only hope for survival


The (a) tarsier, (b) lemur, and (c) liontail macaque monkey all have relatively flat faces, with forward-looking eyes providing binocular vision. All also have color vision and grasping hands. These features, retained from the earliest primates, are shared by humans

  • Some of these adaptations were inherited by humans
    • Large, forward-facing eyes with overlapping fields of view (allowed accurate depth perception)
    • Color vision
    • Grasping hands
    • Enlarged brain (facilitated hand-eye coordination and complex social interactions)
oldest hominid fossils
Oldest Hominid Fossils
  • Hominids include humans and extinct humanlike primates
  • The oldest known hominid fossils are between 6 and 7 million years old
  • Sahelanthropustchadensis lived more than 6 million years ago
    • Exhibits human-like and ape-like characteristics
oldest hominid fossils1
Oldest Hominid Fossils
  • Ardipithecus ramidus and Orrorin tugenensis lived between 4 million and 6 million years ago
  • Knowledge of these earliest hominids is limited - few specimens have been found

The first well-known hominid line, the australopithecines, arose about 4 million years ago

the earliest hominids
The Earliest Hominids
  • The earliest australopithecines possessed knee joints that permitted bipedal (upright, two-legged) locomotion
    • 4 million year old fossilized footprints confirm that early australopithecines sometimes walked upright

An upright stance was significant in the evolution of hominids because it freed their hands from use in walking

the australopithecines
The Australopithecines
  • Several species of Australopithecus have been identified from fossils
  • Australopithecus anamensis
  • Australopithecus afarensis – believed to have given rise to:
    • A. africanus
    • A. robustus
    • A. boisei
  • All australopithecines were extinct by 1.2 million years ago
the genus homo
The Genus Homo
  • The genus Homo diverged from the australopithecine line 2.5 million years ago
the genus homo1
The Genus Homo
  • Homo habilis appeared 2.5 million years ago
    • Bodies and brains were larger than australopithicenes
    • Retained apelike long arms and short legs
  • Homo ergaster appeared 2 million years ago
    • Limb proportions were more like those of modern humans
the genus homo2
The Genus Homo
  • Homo ergaster is believed by many to be the common ancestor of:
    • H. erectus(first hominid species to leave Africa approximately 1.8 million years ago)
    • H. heidelbergensis
      • Some migrated to Europe and gave rise to H. neanderthalensis
      • Those remaining in Africa gave rise to H. sapiens (modern man)
advances in tool technology
Advances in Tool Technology
  • Hominid evolution is closely tied to the development of tools
  • Homo habilis produced fairly crude chopping tools that were unchipped on one end to hold in the hand
advances in tool technology1
Advances in Tool Technology
  • Homo ergaster produced finer tools that were typically sharp all the way around the stone
    • Some of these may have been tied to spears
advances in tool technology2
Advances in Tool Technology
  • Homo neanderthalensis produced exceptionally fine tools with extremely sharp edges made by flaking off tiny bits of stone
the neanderthals
The Neanderthals
  • Neanderthals lived in Europe from 150,000 to 30,000 years ago
  • They were heavily muscled, had brains slightly larger than modern humans, walked fully erect, and constructed finely crafted stone tools

Neanderthals were once believed to be a variety of H. sapiens; however, molecular evidence indicates that Neanderthals are a separate species

modern humans
Modern Humans
  • Homo sapiens appeared in Africa about 160,000 years ago
  • European and Middle Eastern H. sapiens appeared about 90,000 years ago and were known as Cro-Magnons
cro magnons
  • Cro-Magnons had domed heads, smooth brows, and prominent chins
  • 30,000-year-old Cro-Magnon artifacts include:
    • Bone flutes
    • Ivory sculptures
    • Evidence of elaborate burial ceremonies

Unlike their predecessors, Cro-Magnons created remarkable cave paintings that made use of sophisticated artistic techniques

cro magnons and neanderthals
Cro-Magnons and Neanderthals
  • Cro-Magnons coexisted with Neanderthals in Europe and the Middle East for as many as 50,000 years
  • It is not known why the Neanderthals became extinct
  • Two hypotheses have been proposed for the evolution of Homo sapiens
    • “African replacement” hypothesis
    • “Multiregional origin” hypothesis
african replacement hypothesis
“African Replacement” Hypothesis
  • Members of the genus Homo made repeated long-distance migrations out of Africa beginning 1.8 million years ago
  • H. sapiens emerged from Africa about 150,000 years ago and spread across the Near East, Europe, and Asia

The dispersing H. sapiens populations replaced all other hominids

multiregional origin hypothesis
“Multiregional Origin” Hypothesis
  • H. erectus emerged from Africa 1.8 million years ago and spread across the Near East, Europe, and Asia
  • Continued migrations and interbreeding occurred among widespread H. erectus populations
  • Regional populations of H. erectus evolved into H. sapiens
large brains
Large Brains
  • Highly developed brains may have evolved in response to increasingly complex social interactions, such as the cooperative hunting of large game
  • If the distribution of this group-hunted meat was best accomplished by individuals with large brains, then natural selection may have favored such individuals
  • Characteristics made possible by a large brain
    • Language
    • Abstract thought
    • Advanced culture
the cultural evolution of humans
The Cultural Evolution of Humans
  • The evolutionary success of humans is the result of cultural evolution and a series of technological revolutions
    • The development of tools
    • The agricultural revolution
    • The industrial revolution

“We may not be suited for our role as stewards of life’s continuity on Earth, but here we are.”

Stephen Jay Gould