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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• 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
 More successful at passing on genes
Examples:
• Disease immunity or resistance
http://evolution.berkeley.edu/evosite/evo101/images/sicklecell.jpg
Examples:
The ability to utilize
another food source
http://fig.cox.miami.edu/~cmallery/150/unity/c1x17b-finches.jpg
• “ 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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• Write down a list of at least 7 adaptations that the Giraffe
posses that increase its fitness within its environments
• 1. Survive
• 2. Reproduce
• Species as members of populations that actually or potentially
interbreed in nature, not according to similarity of appearance
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
Conflict that arises between individuals or groups in the process of
acquiring limited resources
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
• “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)
A niche is what the animal does in its community, its
habitat is where it lives
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• Interspecific - competition between different species
• Intraspecific – competition within the same species
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
 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….
• 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)
Environmental
Survive
(often Interspecific)
• 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
• 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
• 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
• 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
Sexual
Reproduce
(Often Intraspecific)
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• A feature possessed by a single sex that increases reproductive
fitness (generally in vertebrates)…
• 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