Transcript Domestication and Development of Breeds

Domestication and
Development of Breeds
How have these animals
adapted to various special
environmental or genetic
influences?
What is a species?
1. A species is a population of organisms
that have a common Latin name.
a) Members of this group are very closely
related; together with the genus name it
forms the scientific name
What is a species?
2. A population of organisms, other than bacteria,
that can be interbred naturally to produce
fertile offspring
a) The genetic makeup of the two species is so
different that offspring are either not created, die
shortly after birth or are sterile
b) There are exceptions, wolves (Canus lupus) can
successfully produce fertile offspring when bred
with a domestic dog (Canus domesticus), however
tigers (Pontera tigris) and lions (Pantera leo) can
produce ligers or tiglons but are sterile
What is a species?
3. The two species can also be separated by
time
a) It may be possible that domesticated horses
and prehistoric horses could have mated,
but since they don’t exist in the same time
period they are considered different species
What is a species?
4. Environment and space may be a factor
a) Animals that live in a forest and those living
in the plains will never meet and are
considered a different species.
Ex: Dingos and domesticated dogs can successfully
reproduce, but since dingos don’t associate with
humans and dogs are dependent on us they
remain separate populations
What is a species?
5. Social structure and behavior also
presents animals of different species from
coming into contact and reproducing in
the wild
How is a species formed?
1.
New species are created by splitting an
existing species population into two or more
separate groups.
1. These groups must be prevented from interbreeding
either by disturbance, natural barriers, time or some
other “genetic wall”
a) After being separated, the two groups must be
subjected to at least slightly different environments
b) Given enough time these different environments will
force divergent selection to occur to the point where
the groups will become independent and mutually
exclusive species
How do humans effect
genetic changes?
1. Selection can either be natural or motivated
a) Natural selection
i.
ii.
When the environment changes for an unrelated reason.
This change brings about genetic change.
Occurs because it is the path of least resistance
b) Motivated selection
a)
b)
c)
When specific individuals in a population are purposefully
prevented from breeding and others are encouraged to
breed based on the traits that are desirable
Requires a desire to change the nature of the gene pool
Human beings
How is a species formed?

New species are created by splitting an existing
species population into two or more separated
groups.
– Interbreeding prevented by:
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Disturbance
Natural barriers
Time
“Genetic wall”
– Subjected to different environments
– Given time until the point when groups are
independent and mutually exclusive
What effect do humans
have on evolution,
selection, and the genetic
modification of animals?
Human Effect

Selection can either be natural or
motivated
– Natural selection
 When the environment changes for an unrelated
reason. Change brings about genetic change.
 Occurs because it is the path of least resistance.
Human Effect
– Motivated selection
 When specific individuals in a population are
purposefully prevented from breeding and others
are encouraged to breed based on the traits that
are desirable
 Requires a desire to change the nature of the gene
pool
Human Effect
– Humans involved in both types
 Pesticide use is not intended to change the
genetics of the insects. However, insects most
affected are killed first and the resistant insects are
left to breed.
 Most obvious type of motivated selection is the
process of domestication
Human Effect

Domestication-process by which humans
have created an interdependence with
certain animal species.
– Performed in four steps:
1. Develop a loose contact with animals
•
Humans and dogs share common habitats, habits,
behaviors, food sources and territories
2. Confine animals to our environment
3. Motivated selection is used to alter the genetic
make-up population
4. Remaining wild population is systematically
exterminated to separate the domesticated from
wild and increase human dependence
Human Effect
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Domesticated Animals need to be:
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Hardy
Not afraid of humans
Comfort loving
Useful to humans
Able to breed in captivity
Socially oriented