Transcript Effects of Variation

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WHAT IS THE DIFFERENCE
BETWEEN A POPULATION
AND A SPECIES?
 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 MINUTE…
 Write a brief explanation 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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Mutations can make the organism more
competitive.
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TAKE A MINUTES…
Write down a list of at few 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.
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.
COMPETITION OCCURS BECAUSE
OF….
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.
TYPES OF
COMPETITION
Interspecific - competition between different
species
Intraspecific – competition within the same
species
2 BIOLOGICAL IMPERATIVES
 1. Survive
 2. Reproduce
An organism is FIT if it accomplishes these 2 goals in that order.
 In fact once an organisms has accomplished both goals that
organism will often expire soon for a variety of different reasons
FITNESS
“ The relative contribution an individual makes to
the gene pool to the next generation”
Fitness describes how successful an organism is at
accomplishing the 2 biological imperatives.

Cambell, Biology
TO CLARIFY…
A niche is what an organism does in its
community, its habitat is where it lives
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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)
COMPETITIVE
EXCLUSION PRINCIPAL
• “Two species with similar needs for the
same limiting resources cannot coexist in
the same place” –Campbell, Biology
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 generation.
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.
ALSO NOTE
 Artificial selection – human modification of species (ex. Selective
breeding)
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Food
Habitat
Mates
Predation
Disease
Climate
Competition for resources ( invasive 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
INTRASPECIFIC NATURAL
SELECTION…
The drive to reproduce can be strong enough in an
organism to trump that organism’s drive for survival
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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 …
Please
EAT ME!!
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NOTE
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.
ASEXUAL REPRODUCTION
“the creation of new individual's whose genes all come
from one parents without the fusion of egg and
sperm.”
-Campbell Biology
Essentially Cloning the Parent
ASEXUAL REPRODUCTION
 Organisms are well adapted to stable
environments cloning maintains the “best
combination for the current situation”
 Less of a chance to introduce detrimental traits
into the gene pool
 No need to find or compete for mates (saves time
and energy and can reproduce in isolation)
 Can produce a large amount of offspring in a
short amount of time
ASEXUAL REPRODUCTION
Asexual reproduction is best suited to stable
environments in which individuals are already well adapted
to survive.
This is because the “best traits” are identically copied
into each successive generation.
SEXUAL REPRODUCTION
“the creation of Offspring by the fusion of haploid gametes to form
a zygote, which is diploid.”
-Campbell Biology
SEXUAL REPRODUCTION

Adds more variety to the population so as a whole the
population is better situated to survive and prosper in rapidly
changing or new environment.
Best in new or rapidly changing environment.
The Red Queen in “Alice in
Wonder Land” had to run at full
speed just to stay in the same place.
This means that “a species must
continually evolve to survive in a
world full of other evolving
species” –the science of ecology
One example are diseases. A cloned (or asexually
reproduced) population is highly susceptible to being wiped
out by a contagion.
Predator prey relationships are another example
ADAPTIVE RADIATION
 This process of modification over time to fill a variety of niches is
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.
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.
CONVERGENT EVOLUTION
 When unrelated groups have analogous but nonhomologous
features (wings in birds and butterflies, fins in squids and seals), the
process is called convergent evolution (sometimes parallel
evolution) - similar needs produce similar structures, even if they're
based on different architecture. Both support the concepts of
evolutionary change by selection.
Due to similar selection pressures that are
consistent over long periods of time, unrelated
organisms (or distantly related ones) acquire similar
traits to deal with those similar pressures.
CONVERGENT EVOLUTION
ANATOMY
• HOMOLOGOUS STRUCTURES
• ANALOGOUS STRUCTURES
http://evolution.berkeley.edu/evolibrary/home.php
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PUT ANOTHER WAY…
It is “the emergence of numerous species from a
common ancestor introduced into a new
environment, presenting a diversity of new
opportunities and problems”
– Campbell, Biology
This happens in instances when there exist unrealized
opportunities in a new environment.
Over time once rare characteristics are emphasized
and beneficial. This s divergent or directional selection
depending on the circumstance.
DIVERGENT EVOLUTION
 Traits with similar internal structure
are called homologous traits
 When homologous features become
used for different purposes - are no
longer analogous - the process is called
divergent evolution, the splitting of a
family tree in different directions.