Biodiversity and Evolution

1
Chapter 4

• Biodiversity and Evolution

2
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
  life.
• Each cell contains
• Genes, (containing specific DNA molecules) which
  determine what form the cell will take and its
  functions.
• Other parts, which protect the cell and carry out
  the instructions encoded in the cells DNA
  molecules.
• Whats the difference between eukaryotic and
  prokaryotic?
• 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)

3
How Did Life Emerge on the Earth?

• The evolution of life is linked to the physical
  and chemical evolution of the earth.
• 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
  organisms.
• Over time, it is believed that the protocells
  evolved into single-celled, bacterialike
  prokaryotes having the properties we describe as
  life. (p.140)

4
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

5
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

6
Climate Change

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

7
Catastrophic events

• collision events between earth and large
• asteroids

8
Biodiversity

• 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)
• -

9
How did humans become so powerful?

• strong opposable thumbs
• walk upright
• powerful brain allow us to live more
• sustainably

10
Identified.

• 1.8 million of the earths 4-20 million species

11
Components

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

12
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

13
What determines the number of species in an
ecosystem

• size and degree of isolation
• larger islands have more species than smaller

14
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

15
Theory of Island Biogeography
Number of species related to size of the island
16
continued..

• 2 important variables
• size of the island, distance from the mainland
  source of immigrant species
• smaller island - lower species
• density

17
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
  species.
• 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)

18
How Does the Ecological Niche Relate to
Adaptation?

• 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)

19
What Limits Adaptation?

• A change in environment conditions can lead to
  adaptation only for traits already present in the
  gene pool of a population.
• Because each organism must do many things, its
  adaptations are usually compromises
• Even if a beneficial heritable trait is present
  in a population, that populations ability to
  adapt can be limited by its reproductive
  capacity.
• 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)

20
Microevolution

• - 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.
  142)

21
Macroevolution

• 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
  loss.
• Speciation under certain circumstances natural
  selection can lead to an entirely new species.
• Extinction when all of one species is no longer
  existent.

22
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.

23
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)

24
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.

25
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.

26
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.

27
Some general species continued...

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

28
Some general species continued...

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