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Tuesday April 15th
• Essential Question: What resources are essential
for an organism to survive
• Have out Cytochrome C activity from yesterday
• Today how does competition lead to evolution.
Evolution Flowchart
• Populations can either be evolving or stagnant.
In order for a population to evolve the following
must occur
1. There must be competition for resources and
survival between individual
2. There must be variation in the population
3. The traits must be heritable
What Resources does an Organism
Need
Brainstorm a list of items that an organism
needs in order to survive and reproduce.
Resources an Organism Needs
• Organisms need a habitat that will provide
them with
• Food (either a location with sun/thermal vents
for consumers, prey for consumers, other
organisms for decomposers)
• Access to water
• Shelter from the environment and predation
• Access to mates of the same species
Organisms are in competition for these
resources
• Interspecific
competition is
competition
between members
of different species.
• I.E. The lion and
hyena compete for
the same food
source
• What is another
example?
This leads to changes
• Extinctions occur when my adaptations can
no longer gain me the resources needed for
survival
• Invasive species are a concern because they
increase competition and change food chain
at many levels
Competition
• Individual also compete with members of
their own species. There are two ways that
this happens. Biology has coined them contest
and Scrambles
Contests
• Contests are when
organisms directly
fight over resources
due to the species
hierarchical
structure (think
head of the pack)
Scramble
• When organisms
are looking for the
same prey or
resource but need
to hunt for it on
their own. They
are indirectly
competing.
Wednesday April 16th
• Essential Question: What events could lead to
changes in the gene pool of a population
• Finish Notes from Yesterday
• Complete Study Guides
• Turn in Keystone Practice Exams!!!
Microevolution
• Microevolution is the change in the gene pool over
short periods of time. This can be due to.
•
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•
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Mutations
Gene flow
Genetic Drift
Nonrandom mating (A mate is not chosen based on who is
easily available but on their traits)
• Natural Selection (Certain traits in the population are better
suited for the environment leading to selection for those
traits)
Mutations
• A mutation introduces a
new gene to the population
• Mutations to the HOX genes
that effect development
lead to large scale changes
in an organism
• Normally these mutations
are negative
Gene Flow
• A migration of new
individuals across and
geographic barrier
that has different
traits or different
ratios of traits. (gene
flow)
Genetic Drift
• A random series of events
where one of the possible
genes is not passed to any
member of the next
generation (genetic drift).
Selection
• Sexual Selection or Nonrandom Mating
– A mate is not chosen based on who is easily
available but on their traits
• Natural Selection
– Certain traits in the population are better suited
for the environment leading to selection for those
traits
Speciation
• In Order for new species to form they must
stop Breeding
Types of Speciation
• Behavioral- Species only chose to mate with
certain individuals based on specific traits.
• Geographic- Species are separated due to
differences in the geography. One side of the
mountain or another.
• Temporal- Members of the species breed at
different times
Full Speciation
• Speciation is only complete when species can
no longer successfully mate
• This can occur in two ways
– Prezygotic (species physically can’t mate, have a
different number of chromosomes, or
incompatible reproductive structures)
– Postzygotic (species can mate and breed but their
hybrids are unsuccessful)