Transcript Natural selection lecture

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Harmful
Adaptive
No Value
Harmful – These types of mutations are
detrimental to the organism
• Either causing it to be less well adapted
for its environment, or by causing a basic
life function of the animal to function
deficiently or not at all
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Take a minutes…
• Write a brief list of how the albino
organisms color mutation is detrimental to
that organism’s survival in the wild.
Adaptive – These types of mutations cause
the organism to gain some advantage that
increases its ability to survive and
reproduce successfully
Adaptive
Examples:
The ability to utilize another food source
Disease immunity or resistance
Makes the organism more competitive
Examples:
• Disease immunity or resistance
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Examples:
The ability to utilize
another food source
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Fitness
• “ The relative contribution an individual
makes to the gene pool to the next
generation”
•
Cambell, Biology
Makes the organism
more competitive
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http://www.airs.com/ian/giraffe.gif
Take a minutes…
• Write down a list of at least 7 adaptations
that the Giraffe posses that increase its
fitness within its environments
No Value – These types of mutations do
nothing to either harm the organism or to
make them more fit
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Mutations assist a species because they
cause a variety of variations to exist within
that species. Adaptive mutations increase
the fitness of a species by providing
increased variation
• Recurrent mutation – a mutation for a
trait that is genetically different from either
parent, but is already present in the
population
• Novel Mutation – a mutation that results
in a trait that is not already present in the
population
Competition
Conflict that arises between individuals or
groups in the process of acquiring limited
resources
Lets see how this works
Limiting Resource
• Any factor (usually a nutrient) within an
ecosystem that is in finite quantity and that
is required by individuals in that
ecosystem for survival
Competitive
Exclusion
Principal
• “Two species with similar needs for the
same limiting resources cannot coexist in
the same place” –Campbell, Biology
2 types
 Fundamental niche – the resources (biotic and
abiotic) that are theoretically available to an
organism
 Realized niche – the resources (biotic and
abiotic) that are actually utilized by a given
population
(Campbell,
Biology)
To Clarify…
A niche is what the animal does in its community,
its habitat is where it lives
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http://www.nypatriot.com/victorian-house.jpg
Types of Competition
• Interspecific - competition between
different species
• Intraspecific – competition within the
same species
Darwin’s Observations
1.
If all offspring were able to reproduce successfully
populations size would exponentially increase over a few
generations
2.
In natures populations sizes are relatively stable
3.
Limited resources exist in all environments
4.
Individuals within the same species have a variety of
unique and distinct traits (every individual is different)
5.
Many of these variations can be passed on to successive
generations
What this means…
 Competition results when more offspring
are produced then can survive because
resources are limited
Offspring that posses more beneficial
characteristics are more likely to survive
and pass on their genes
Because more fit individuals survive most
often populations will shift over time to
accumulate more beneficial characteristics
• This is called….
NOTE
• Adaptations are not static as environments
change so do the characteristics of a
population. The best combination of traits
changes over time
• Note: species do not develop a trait to
cope with an element in their environment
rather a pool of traits (range of variation)
exist within a given population and those
that are best adapted survive more
frequently and reproduce more
successfully.
• Artificial selection – human modification of
species (ex. Selective breeding)
•
•
•
•
•
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Food
Habitat
Mates
Predation
Disease
Climate
Competition for resources ( invasive
species)
Types of Natural Selection…
Environmental
Survive
(often Interspecific)
Types of Natural Selection…
• Stabilizing Selection
This type of selection encourages the
average or status quo combination of
traits.
It happens in environments where there is
little change occurring
Types of Natural Selection…
• Directional Selection
This type of selection favors a specific
combination of traits that were relatively
rare in the original population
It happens in environments where there is
great change occurring or is a species is
moving into a new environment
Types of Natural Selection…
• Diversifying Selection
This type of selection favors traits on either
end of the spectrum but not the middle
It happens in environments where there is
change but the new factors favor multiple
variations, this often happens in a
divergence of species
Note…
• Only traits that already exist in a
population can be selected for
• Every adaptation is also a compromise
• Every adaptation has to be based on a
preexisting element of the organism
• There cannot be a permanently perfect
organism
Types of Natural Selection…
Sexual
Reproduce
(Often Intraspecific)
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• A feature possessed by a single sex that
increases reproductive fitness (generally in
vertebrates)…
Important
• Reproductive fitness can (but doesn’t have
to) detract significantly from the
environmental fitness of an individual ie.
The Peacock …
Important
Please
EAT ME!!
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Sexual secondary characteristic can assist
the animal in survival such as a deer’s
antlers, but it is often the females that
determine the fitness of a Sexual
dimorphism