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Biodiversity and Evolution


Chapter 4 Biodiversity and Evolution – PowerPoint PPT presentation

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Title: Biodiversity and Evolution

Chapter 4
  • Biodiversity and Evolution

Chapter 6Evolution and Biodiversity
  • What is biodiversity?
  • Biodiversity is the variety of earths species,
    the genes they contain, the ecosystems in which
    they live, and the ecosystem processes such as
    energy flow and nutrient cycling that sustain all
  • Each cell contains
  • Genes, (containing specific DNA molecules) which
    determine what form the cell will take and its
  • Other parts, which protect the cell and carry out
    the instructions encoded in the cells DNA
  • Whats the difference between eukaryotic and
  • Eukaryotic cells are surrounded by a membrane
    and have a nucleus and several other internal
    parts, and all bacterial cells are prokaryotic,
    without a distinct nucleus or other internal
    parts enclosed by membranes. (p. 133 and p. 134)

How Did Life Emerge on the Earth?
  1. The evolution of life is linked to the physical
    and chemical evolution of the earth.
  2. Life on earth evolved in two phases over the past
    4.7 4.8 billion years Chemical Evolution (1
    billion years) of the organic molecules,
    biopolymers, and systems of chemical reactions
    needed to form the first protocells and
    Biological Evolution (3.7 billions years) of
    single-celled organisms and then multicellular
  3. Over time, it is believed that the protocells
    evolved into single-celled, bacterialike
    prokaryotes having the properties we describe as
    life. (p.140)

Biological Evolution
  • By Natural Selection, explains how life
  • changes over time
  • Adaptation or Adaptive traits enables an
  • organism to survive through natural selection
  • to reproduce under prevailing environmental
  • conditions

Geological Processes and Climate Change affect
  • Huge flows of molten rock within the earths
    interior break into surfaces into a series of
    gigantic solid plates TECTONIC PLATES
  • Plates have drifted atop planets mantle
  • Locations of continents and oceans basin
  • influence earths climate
  • species move, adapt to new environments
  • earthquakes, volcanic eruptions

Climate Change
  • alternate periods of heating and cooling
  • advance and retreats of ice sheets at high
  • latitudes over northern hemispheres

Catastrophic events
  • collision events between earth and large
  • asteroids

  • Speciation
  • geographic isolation
  • reproductive isolation
  • Extinction
  • endemic
  • species more vulnerable
  • Background Extinction
  • 1-5 /million species
  • Mass Extinction 5 extinctions 20-60 million
    years apart
  • in the last 500 million years (20-60 million
    years apart)
  • -

How did humans become so powerful?
  • strong opposable thumbs
  • walk upright
  • powerful brain allow us to live more
  • sustainably

  • 1.8 million of the earths 4-20 million species

  • species diversity
  • genetic diversity
  • ecosystem diversity
  • functional diversity

Importance of species diversity
  • species richness number of different species
  • species evenness- relative abundance of
    individuals within each of those species
  • species diversity varies with geographic location
  • species rich ecosystems are productive and
  • sustainable

What determines the number of species in an
  • size and degree of isolation
  • larger islands have more species than smaller

Theory of Island Biogeography
  • number of species found on the island determined
    by (a) immigration rate of species to the island
    from other inhabited areas
  • and (b) extinction rate of species established on
    the island

Theory of Island Biogeography
Number of species related to size of the island
  • 2 important variables
  • size of the island, distance from the mainland
    source of immigrant species
  • smaller island - lower species density

Evolution and Adaptation
  • What is evolution?
  • -AKA biological evolution
  • -The change in a populations genetic makeup
    through sucesive generations.
  • What is theory of evolution?
  • -All species descended from earlier, ancestral
  • Types of biological evolution
  • -microevolution
  • -macroevolution
  • -gene pool sum of all genes possessed by the
    individuals of the population.
  • - Alleles genes with more than two or more
    different molecular forms. (p. 141)

How Does the Ecological Niche Relate to
  • Evolution by natural selection leads to a
    remarkable fit between organisms and their
    environment. In terms of the ecological niche of
    a particular species, this fit involves having a
    set of traits that enables individuals to
    survives and reproduce in a particular
    environment. Species that have similar niches
    tend to evolve similar sets of traits, even if
    they are unrelated species growing in different
    parts of the world. (p. 145)

What Limits Adaptation?
  1. A change in environment conditions can lead to
    adaptation only for traits already present in the
    gene pool of a population.
  2. Because each organism must do many things, its
    adaptations are usually compromises
  3. Even if a beneficial heritable trait is present
    in a population, that populations ability to
    adapt can be limited by its reproductive
  4. Even if a favorable genetic trait is present in a
    population, most of its members would have to die
    or become sterile so that individuals with the
    trait could predominate and pass the trait on.
    (p. 146)

  • - Microevolution works through a combination
    of four processes that change the genetic
    composition of a population
  • Mutation involving random changes in the
    structure or number of DNA molecules in a cell
    and is the ultimate source of genetic variability
    in a population.
  • Natural selection occurs when some individuals
    of a population have genetically based traits
    that cause them to survive and produce more
    offspring than other individuals
  • Gene flow which involves movement of genes
    between populations and can lead to changes in
    the genetic composition of local populations.
  • Genetic drift involves changes in the genetic
    composition of a population by chance and is
    especially important for small populations. (p.

  • What is macroevolution?
  • Macroevolution is concerned with how evolution
    takes place above the level of species and over
    much longer periods than microevolution, and
    macro evolutionary patterns include genetic
    persistence, genetic divergence, and genetic
  • Speciation under certain circumstances natural
    selection can lead to an entirely new species.
  • Extinction when all of one species is no longer

Sustainability and Evolution
  • Earth is constantly changing, and throughout the
    earths history the atmosphere has changed, the
    climte has changed, the geography has changed he
    types and numbers of organisms have changes, and
    continental drift has changed the positions of
    the earths continents.
  • Biologists estimate that the current
    human-accerlated extinction rate of species is
    1,000 to 10,000 times higher than natural
    extinction rates.

Adaptation and the Ecological Niche
  • What is the ecological niche?
  • Ecological niche is the species way of life or
    functional role in an ecosystem. A speciess
    niche involves everything that affects its
    survival and reproduction. This includes..
  • The range of tolerance for various physical and
    chemical condisitons
  • The types of resources it uses, such as food or
    nutrient requirements
  • How it interacts with other living and nonliving
    components of the ecosystems in which it is found
  • The role it plays in the flow of energy and
    cycling of matter in an ecosystem. (p. 145)

The Ecological Niche
  • Each species has a particular ecological niche or
    role it plays in ecosystem.
  • Niche of species differs from its habitat--
    actual physical location where organisms making
    up species live.
  • Ecological niche can be defined by ranges of
    conditions and resources where organisms can live.

What is the Difference Between Fundamental Niche
and Realized Niche?
  • Fundamental Niche- full potential range of
    conditions and resources it could theoretically
    use if there werent direct competition from
    other species.
  • Realized Niche- parts of the fundamental niche of
    a species actually used by that species.

Some General Types of Species...
  • Native species species that normally live
    thrive in a particular ecosystem.
  • Nonnative species, Exotic species, Alien species
    other species that migrate into an ecosystem or
    are introduced into an ecosystem by humans.

Some general species continued...
  • Indicator species species that serve as early
    warnings that a community or an ecosystem is
    being damaged.

Some general species continued...
  • Keystone Species species that play roles
    affecting many other organisms in an ecosystem.
  • Dung beetle
  • Sea otters
  • Gopher tortoises
  • Bats
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