Something in the environment that effects an organisms ability to survive or reproduce. Usually leading to evolution by alteration of genetic makeup.

Survival of the fittest:

Organisms that are better adapted to their environment are more likely to survive and thus reproduce, causing the characteristic enabling the best adapted individuals to be passed on through generations.

How often an Allele occurs in a population (such as allele for blue eyes occuring 20% (or 0.20) of the time in humans).

Is the change in allele frequency in a population over generations. This occurs by natural selection.

The formation of new species from a population in which some individuals become Reproductively Isolated.

Reproductive Isolation:

When two organisms are unable to produce offspring that is healthy and fertile.

Allopatric Speciation:

The process of speciation (formation of new species) when a Geographical Barrier results in reproductive isolation.

Sympatric Speciation:

The speciation which occurs when individuals become reproductively isolated from each other in the same area.

Prezygotic Isolation:

Isolating Mechanisms that prevent the formation of a Zygote.

Postzygotic Isolation:

Isolating mechanisms that prevent the production of fertile and healthy offspring.

Give 5 Examples of Prezygotic Isolating Mechanisms:

Geographical Isolation, Morphological Isolation, Behavioural Isolation, Temportal Isolation, Gamete Incompatability.

Geographical Isolation:

The isolation that occurs when two populations are separated by a barrier, such as the formation of Moutains, Rivers altering course and climate change.

Individuals become active at different times of the day, meaning they never end up crossing paths, thus have no chance to mate.

Gamete Incompatability:

The transfer of sperm is possible but fertilisation does not occur (Acrosome contains the wrong hydrolytic enzymes)

Behavourial Isolation:

When individuals no longer preform mating rituals that attract each other etc.

Give 4 Examples of Postzygotic Isolation:

Zygote Mortality, Hybrid Inviablity, Hybride degeneration and Hybride Sterility.

The gametes are able to fuse but a zygote is not formed.

The zygote formed from fertilisation of gametes is inviable and does not make it to term.

When the offspring formed is not fertile so cannot produce offspring of its own.

When the offspring of a mix is fertile but its offspring isn't.

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Evolution speciation

Evolution by Mutation, Natural Selection. Speciation and Evidence.

Question	Answer
Selection Pressure:	Something in the environment that effects an organisms ability to survive or reproduce. Usually leading to evolution by alteration of genetic makeup.
Survival of the fittest:	Organisms that are better adapted to their environment are more likely to survive and thus reproduce, causing the characteristic enabling the best adapted individuals to be passed on through generations.
Allele Frequency:	How often an Allele occurs in a population (such as allele for blue eyes occuring 20% (or 0.20) of the time in humans).
Evolution:	Is the change in allele frequency in a population over generations. This occurs by natural selection.
Speciation:	The formation of new species from a population in which some individuals become Reproductively Isolated.
Reproductive Isolation:	When two organisms are unable to produce offspring that is healthy and fertile.
Allopatric Speciation:	The process of speciation (formation of new species) when a Geographical Barrier results in reproductive isolation.
Sympatric Speciation:	The speciation which occurs when individuals become reproductively isolated from each other in the same area.
Prezygotic Isolation:	Isolating Mechanisms that prevent the formation of a Zygote.
Postzygotic Isolation:	Isolating mechanisms that prevent the production of fertile and healthy offspring.
Give 5 Examples of Prezygotic Isolating Mechanisms:	Geographical Isolation, Morphological Isolation, Behavioural Isolation, Temportal Isolation, Gamete Incompatability.
Geographical Isolation:	The isolation that occurs when two populations are separated by a barrier, such as the formation of Moutains, Rivers altering course and climate change.
Temporal Isolation:	Individuals become active at different times of the day, meaning they never end up crossing paths, thus have no chance to mate.
Gamete Incompatability:	The transfer of sperm is possible but fertilisation does not occur (Acrosome contains the wrong hydrolytic enzymes)
Behavourial Isolation:	When individuals no longer preform mating rituals that attract each other etc.
Give 4 Examples of Postzygotic Isolation:	Zygote Mortality, Hybrid Inviablity, Hybride degeneration and Hybride Sterility.
Zygote Mortality:	The gametes are able to fuse but a zygote is not formed.
Hybrid Inviability:	The zygote formed from fertilisation of gametes is inviable and does not make it to term.
Hybrid Sterility:	When the offspring formed is not fertile so cannot produce offspring of its own.
Hybrid Degredation:	When the offspring of a mix is fertile but its offspring isn't.

Created by: mjwilson1988

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