Biodiversity

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Biodiversity

• How Diverse is Life?

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How did Life Originate?

• A small pond?
• In hydrothermal vents at the bottom of the ocean?
• In heat-stressed ponds near ancient volcanoes?
• In clay beds in estuary or bays?

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Early Speculation

• 1920s and 1930s
• A.I. Oparin and J.B.S. Haldane hypothesized about
  the Earths early atmosphere.
• Little free oxygen and abundance of methane,
  ammonia, nitrogen, water vapor and perhaps free
  hydrogen.
• Earthquakes and lightening very common.
• Speculations not well-received due to lack of
  evidence.

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Experiments Spontaneously Produced Organic
Compounds

• 1952 Miller and Urey built an apparatus to
  model Oparins and Haldanes hypothesized
  atmosphere.
• After a week, amino acids were formed.

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Experiments Spontaneously Produced Organic
Compounds

• Other scientists repeated experiments and varied
  the gas composition and other conditions.
• Carbohydrates, lipids, components of RNA and DNA
  and other amino acids were produced.
• Astronomers commonly observed carbon-based
  compounds throughout the universe

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Experiments Spontaneously Produced Organic
Compounds

• More recently, astronomers and geologists are
  convinced Earths atmosphere was different than
  Haldane and Oparin hypothesized.
• Earth atmosphere was more likely composed of
  carbon dioxide, nitrogen and water vapor.
• Speculation continues.

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Next Step Was to Move Beyond Isolated
Carbon-Based Compounds to Cells

• Possible scenarios for producing proteins
• In ancient oceans, evaporation would concentrate
  amino acids which would make them likely to
  combine to form proteins.
• Ocean bubbles would have powerful electrostatic
  forces inside that would attract amino acids,
  drawing them closer to interact.
• Iron pyrite crystals and clay crystals could
  attract and concentrate amino acids.

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Next Step Was to Move Beyond Isolated
Carbon-Based Compounds to Cells

• Possible scenarios for producing phospholipids
• Ancient bubbles made of phospholipids could
  exist.
• Would pop and allow mixing of chemicals contained
  inside the bubble.
• Ultimately result in the production of
  protocells.

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Next Step Was to Move Beyond Isolated
Carbon-Based Compounds to Cells

• Protocells
• Non-living organism
• Important characteristic of life
• Ability to reproduce.
• 1993, scientists found small molecule of
  synthetic RNA that could quickly make copies of
  itself.
• Current investigations are trying to determine
  how life evolved on the Earth.

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What Were the Major Milestones in the Earths
Evolving Biodiversity?

• Tendency to view organisms appearing later in
  life as superior to those appearing earlier in
  the history of the Earth.
• Important to remember
• From a biological standpoint, complexity does not
  equate success .
• Success involves surviving and acquiring enough
  energy and nutrients to reproduce and pass useful
  characteristics to offspring.

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First Cells Evolved into the Different Cell Types
We See Today

• Earths first organisms
• Single-celled heterotrophs (lack an ability to
  make food)
• Consumed naturally occurring carbon-based
  compounds
• With exhaustion of compounds, heterotrophs
  evolved single-celled and multicellular
  decomposers, scavengers and predators.

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First Cells Evolved into the Different Cell Types
We See Today

• Autotrophs evolved from heterotrophs.
• Autotroph cells that produce chemicals that
  store energy.
• Trapped light-absorbing pigments that made it
  possible to utilize energy from the sun.
• Later these organisms evolved and were able to
  photosynthesize.

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Simple Cells Evolved into More Complex Cells

• Eukaryotic cells evolved from prokaryotic cells.
• Two processes involved
• In-pocketing of cell membranes that specialized
  and evolved into organelles.
• Examples nucleus, Golgi complex, endoplasmic
  reticulum
• Endosymbiosis
• theory that mitochondria and chloroplasts were
  prokaryotes that developed means to efficiently
  obtain energy.
• Mitochondria and chloroplasts intimately
  associate with eukaryotic cell and become an
  organelle in eukaryotic cells.

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Single-Celled Organisms Evolved into Multicelled
Organisms

• Multicelluarity evolved whenever some colonial
  cells specialized.
• Example concentrating on movement, food
  digestion, reproduction.
• As a result, other cells depend on specialized
  cells for those functions.

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Milestones in Evolution of Animals

• Presence or absence of tissue
• The body type
• Symmetry, radial, or bilateral
• The number of embryonic germ layers
• Either two or three

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Milestones in Evolution of Animals

• Presence or absence of body cavities (coeloms).
• Bilateral animals fall into 3 categories
• No cavities acoelomates
• Cavity between mesoderm and endoderm
  psuedocoelomates
• Coeloms are surrounded by mesoderm coelomates

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Milestones in Evolution of Animals

• The embryonic timing of cell specialization among
  the coelomates
• Primitive coelomates cells commit early cell
  specialization.
• Advanced coelomates cells commit later in
  embryonic development.
• Location and method tissues develop.
• Primitive coelomates blastopore becomes the
  mouth.
• Advanced coelomates blastopore becomes the
  anus.

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Milestones in Evolution of Animals

• Presence or absence of a skeleton, as well as the
  type of skeleton.
• Segmented worms have hydrostatic skeleton
• Shellfish and arthropods have exoskeleton
• Spiny-skinned animals and those with backbones
  have endoskeleton

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How Do Biologists Keep Track of So Many Species?

• Same problem exists in the grocery store.
• How to categorize different foods
• Biologist need to categorize more than 1.5
  million species.

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Purposes of Biological Classification

• To assist in species identification.
• To assign formal, consistent scientific names to
  species.
• To describe ancestral relationships between
  species.

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Initial Classification was Concerned With
Describing Natural Order

• Taxonomy began with Aristotle
• Classified groups using either-or comparison
• Example animal or plant
• Early days of classification, dominant
  philosophical view
• Species were fixed, unchanging and could be
  arranged in natural order.
• Species description sought to list each species
  idealized characteristics.
• Became the archetype.

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Karl von Linne

• 1707-1778
• Wrote meticulous detailed descriptions about
  plants and animals.
• Described over 8,000 plants and animals.
• Gave each two Latinized names.
• Unique to each

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Karl von Linne

• First name genus
• Closely related forms could share this name and
  be grouped together.
• Second name species
• Not shared by closely related forms.
• Called binomial nomenclature.

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Karl von Linne

• Generated higher taxonomic categories
• Related genera combined into Orders
• Related orders combined into Classes
• Highest categories were Kingdoms
• Two kinds Plant and Animal

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Classification after Darwin and Mendel

• Archetype replaced by type specimen.
• First specimen collected or a representative
  specimen of the given species
• Effect of Mendel
• Taxonomists shift to emphasizing the
  characteristics that differentiate one distinct
  population of species from another.

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Classification Today

• Primary objective today
• describe the evolutionary relationships between
  species.
• Use modern tools to describe relationships.

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Classification Today

• Molecular biochemistry allows scientists to
  compare proteins, DNA and RNA from different
  species.
• More accurate for determining relationships than
  relying upon comparisons of structure and form.

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How Does The System Work?

• Place organisms into a series of hierarchical
  groups called taxa.
• Broadest group contains most organisms
• These are subdivided into smaller categories
  until level of individual species is reached.
• All organism within a particular taxa share
  certain characteristics.

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History of Classification
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At First Two Kingdoms, Now at Least Five

• From Aristotle to middle of 20th century
• Two kingdoms Plant and Animal
• There were exceptions such as fungi
• Sessile and had thick-walled cells like plants
• But were not photosynthetic

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Transitions

• Another exception
• Euglena
• One-celled organism with tail and no cell wall
• In the summer, had chloroplasts and would perform
  photosynthesis
• Winter would function as a decomposer
• Is it an animal or plant?

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Transitions

• Create more kingdoms to solve the problem.
• Protista would include Euglena and other similar
  organism.
• Monera would accommodate bacteria (single-celled
  prokaryotes).
• Additional new kingdom to accommodate Fungi.

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Transitions

• Recently a need to create category larger than
  kingdoms, the domains.
• Due to Archaea which are different than
  prokaryotes and eukaryotes.

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Within Each Kingdom, There Are Additional
Categories

• Domain Eukarya
• All members have one characteristic in common
  their cells are eukaryotes.
• Much diversity in the kingdom.
• Requiring subdivision to classify organisms.

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Within Each Kingdom, There Are Additional
Categories

• Since kingdoms contain wide variety of organisms,
  it becomes important to classify organisms into
  sub-categories.
• The taxa indicate evolutionary relationships.

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Domain Eukarya Has Four Kingdoms

• Protista
• single-celled and simple multicelled eukaryotes.
• Fungi
• single-celled and multicelled, eukaryotic,
  heterotrophic organisms with thick-walled cells.
• Plantae
• Multicellular, eukaryotic, autotrophic organisms
  with thick-walled cells.
• Animalia
• Multicellular, eukaryotic, heterotrophic
  organisms with cells that have no walls.

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What Is Happening to Earths Biodiversity?

• Life on Earth is disappearing
• Today only a fraction of the estimated 75 million
  bison that greeted the first Europeans.
• Songbird numbers are consistently down throughout
  the world.

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Human Activities are Causing Mass Extinctions

• Root of the problem is human population growth.
• Resulting in competition for resources with other
  species and humans usually win.

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Human Activities are Causing Mass Extinctions

• Size of human population results in
• Habitat loss
• 50 years ago, cities with 1 million people were
  rare
• Not true today.
• A need for more farmland.
• A need for various infrastructure such as
• Roads, railways, dams.

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Human Activities are Causing Mass Extinctions

• Chemicals produced by human activities and
  released into the environment
• Plastics, fuels, solvents, cleaning compounds
  leak or are purposely put into soils, waterways,
  or the atmosphere.
• Adversely affecting reproductive rates of animals
  and their populations.

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Human Activities are Causing Mass Extinctions

• Alien species
• Those that flourish in regions where they are not
  native.
• Introduced to new environments due to human
  activities.
• Replace native species and overwhelming local
  resources.

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Humans Are Dependent on Healthy Populations of
Other Organisms

• Plants convert the carbon dioxide we produce into
  oxygen we cannot live without.
• Deforestation contributes to increased flooding.
• As human population increases, so does our waste.
  
• Wetlands can help with the decomposition of waste.

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Humans Are Dependent on Healthy Populations of
Other Organisms

• Penicllium
• a fungus that spoils fruit and bread also
  produces a product that kills bacteria.
• Yew trees
• Bark from this tree contains an extract that
  helps control human cancers.

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We Can Preserve Our Biodiversity

• Human activities can be directed to building up
  rather than tearing down our environment.
• Preserve habitats by establishing parks and
  refugees specifically for wildlife.
• Restoration ecology goal is to transform spent
  mines, worn-out farmland, deforested slopes and
  even unprofitable shopping centers.
• Most important to maintaining biodiversity is
  citizen involvement.