Domestication and Domestication and Development of Development of

BreedsBreeds

How have these animals How have these animals adapted to various adapted to various

special environmental or special environmental or genetic influences?genetic influences?

What is a species?What is a species?

1. A species is a population of 1. A species is a population of organisms that have a common organisms that have a common Latin name.Latin name.

a)a) Members of this group are very closely Members of this group are very closely related; together with the genus name related; together with the genus name it forms the scientific nameit forms the scientific name

What is a species?What is a species?

2. A population of organisms, other than 2. A population of organisms, other than bacteria, that can be interbred naturally to bacteria, that can be interbred naturally to produce fertile offspringproduce fertile offspring

a)a) The genetic makeup of the two species is so The genetic makeup of the two species is so different that offspring are either not created, different that offspring are either not created, die shortly after birth or are steriledie shortly after birth or are sterile

b)b) There are exceptions, wolves (There are exceptions, wolves (Canus lupusCanus lupus) can ) can successfully produce fertile offspring when bred successfully produce fertile offspring when bred with a domestic dog (with a domestic dog (Canus domesticusCanus domesticus), ), however tigers (however tigers (Pontera tigrisPontera tigris) and lions ) and lions ((Pantera leoPantera leo) can produce ligers or tiglons but ) can produce ligers or tiglons but are sterileare sterile

What is a species?What is a species?

3. The two species can also be 3. The two species can also be separated by timeseparated by time

a)a) It may be possible that domesticated It may be possible that domesticated horses and prehistoric horses could horses and prehistoric horses could have mated, but since they don’t exist have mated, but since they don’t exist in the same time period they are in the same time period they are considered different speciesconsidered different species

What is a species?What is a species?

4. Environment and space may be a 4. Environment and space may be a factorfactor

a)a) Animals that live in a forest and those Animals that live in a forest and those living in the plains will never meet and living in the plains will never meet and are considered a different species. are considered a different species. Ex: Dingos and domesticated dogs can Ex: Dingos and domesticated dogs can

successfully reproduce, but since dingos successfully reproduce, but since dingos don’t associate with humans and dogs are don’t associate with humans and dogs are dependent on us they remain separate dependent on us they remain separate populationspopulations

What is a species?What is a species?

5. Social structure and behavior also 5. Social structure and behavior also presents animals of different species presents animals of different species from coming into contact and from coming into contact and reproducing in the wildreproducing in the wild

How is a species formed?How is a species formed?

1.1. New species are created by splitting an New species are created by splitting an existing species population into two or more existing species population into two or more separate groups.separate groups.

1.1. These groups must be prevented from These groups must be prevented from interbreeding either by disturbance, natural interbreeding either by disturbance, natural barriers, time or some other “genetic wall”barriers, time or some other “genetic wall”

a)a) After being separated, the two groups must be After being separated, the two groups must be subjected to at least slightly different subjected to at least slightly different environmentsenvironments

b)b) Given enough time these different environments Given enough time these different environments will force divergent selection to occur to the will force divergent selection to occur to the point where the groups will become independent point where the groups will become independent and mutually exclusive speciesand mutually exclusive species

How do humans effect How do humans effect genetic changes?genetic changes?

1. Selection can either be natural or motivated1. Selection can either be natural or motivateda)a) Natural selectionNatural selection

i.i. When the environment changes for an unrelated When the environment changes for an unrelated reason. This change brings about genetic change.reason. This change brings about genetic change.

ii.ii. Occurs because it is the path of least resistanceOccurs because it is the path of least resistance

b)b) Motivated selectionMotivated selectiona)a) When specific individuals in a population are When specific individuals in a population are

purposefully prevented from breeding and others are purposefully prevented from breeding and others are encouraged to breed based on the traits that are encouraged to breed based on the traits that are desirabledesirable

b)b) Requires a desire to change the nature of the gene Requires a desire to change the nature of the gene poolpool

c)c) Human beingsHuman beings

How is a species formed?How is a species formed?

New species are created by splitting an New species are created by splitting an existing species population into two or existing species population into two or more separated groups.more separated groups.– Interbreeding prevented by:Interbreeding prevented by:

DisturbanceDisturbance Natural barriersNatural barriers TimeTime ““Genetic wall”Genetic wall”

– Subjected to different environmentsSubjected to different environments– Given time until the point when groups are Given time until the point when groups are

independent and mutually exclusiveindependent and mutually exclusive

What effect do humans What effect do humans have on evolution, have on evolution, selection, and the selection, and the

genetic modification of genetic modification of animals?animals?

Human EffectHuman Effect

Selection can either be natural or Selection can either be natural or motivatedmotivated– Natural selectionNatural selection

When the environment changes for an When the environment changes for an unrelated reason. Change brings about unrelated reason. Change brings about genetic change.genetic change.

Occurs because it is the path of least Occurs because it is the path of least resistance.resistance.

Human EffectHuman Effect

– Motivated selectionMotivated selection When specific individuals in a population are When specific individuals in a population are

purposefully prevented from breeding and purposefully prevented from breeding and others are encouraged to breed based on others are encouraged to breed based on the traits that are desirablethe traits that are desirable

Requires a desire to change the nature of Requires a desire to change the nature of the gene poolthe gene pool

Human EffectHuman Effect

– Humans involved in both typesHumans involved in both types Pesticide use is not intended to change the Pesticide use is not intended to change the

genetics of the insects. However, insects genetics of the insects. However, insects most affected are killed first and the most affected are killed first and the resistant insects are left to breed.resistant insects are left to breed.

Most obvious type of motivated selection is Most obvious type of motivated selection is the process of domesticationthe process of domestication

Human EffectHuman Effect

DomesticationDomestication-process by which -process by which humans have created an humans have created an interdependence with certain animal interdependence with certain animal species.species.

– Performed in four steps:Performed in four steps:1.1. Develop a loose contact with animalsDevelop a loose contact with animals

• Humans and dogs share common habitats, habits, Humans and dogs share common habitats, habits, behaviors, food sources and territoriesbehaviors, food sources and territories

2.2. Confine animals to our environmentConfine animals to our environment3.3. Motivated selection is used to alter the Motivated selection is used to alter the

genetic make-up populationgenetic make-up population4.4. Remaining wild population is systematically Remaining wild population is systematically

exterminated to separate the domesticated exterminated to separate the domesticated from wild and increase human dependencefrom wild and increase human dependence

Human EffectHuman Effect

Domesticated Animals need to be:Domesticated Animals need to be:– HardyHardy– Not afraid of humansNot afraid of humans– Comfort lovingComfort loving– Useful to humansUseful to humans– Able to breed in captivityAble to breed in captivity– Socially orientedSocially oriented