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Back to MACROevolution. What does it mean again?. large-scale evolutionary changes including the formation of new species & taxa . happens over a much longer period of time (centuries, millenia ). Recall from Grade 9 Ecology. A population is.

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Back to macroevolution

Back to MACROevolution

What does it mean again?

  • large-scale evolutionary changes including the formation of new species & taxa.

  • happens over a much longer period of time (centuries, millenia).

Recall from grade 9 ecology

Recall from Grade 9 Ecology....

A population is...

a group of the same species of living things (i.e. All the people on planet Earth).

A community is...

groups of different species of living things in an area (i.e. All the frogs, snakes, fish, & lily pads in a pond ecosystem).

Development vs evolution

Development vs. Evolution

What’s the difference?

Development refers to changes that happen to an organism as it progresses through its life cycle.

Evolution refers to changes that occur in an entire population over a very long period of time.

What is a species

What is a “species”???

A group of individuals that actually or potentially interbreed in natureto produce viable or fertile offspring.

These happy face spiders look different, but since they can interbreed, they are considered the same species: Theridiongrallator.

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Result of male tiger and female lion mating in captivity. Offspring are infertile.

Back to macroevolution


Result of male lion and female tiger mating in captivity. Offspring are infertile.



  • The formation of a new species

  • The original species must to become reproductively isolated from the rest of the population (reproductive isolation)

Reproductive isolation

Reproductive Isolation

  • Members of two populations cannot interbreed and produce fertile offspring

  • Two types:

    • pre-zygotic mechanisms

    • post-zygotic mechanisms

Pre zygotic mechanisms

Pre-zygotic Mechanisms

prevents different species from mating and fertilizing

Post zygotic mechanisms

Post-zygotic Mechanisms

prevents maturation and reproduction of interspecies offspring

Modes of speciation

Modes of Speciation

Allopatric Speciation: Evolution of population into two different species caused by geographic isolation (e.g. Rivers, canyons, mountains, large bodies of water)

The barrier prevents species from interbreeding, which causes them to slowly change until they become so different that they are reproductively isolated

Modes of speciation1

Modes of Speciation

Sympatric Speciation: Evolution of populations into new species within the same geographical area

A significant mutation happens to work out, resulting in reproductive isolation of the two populations

Example: hawthorn fly vs. Apple maggot flies in North America

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Note: Over time, the genetic differences between the two populations are enough that they can then lead to speciation.



Answer the following question: What type of speciation do human built structures (i.e. Roads) likely cause?

2. Theories of Evolution Assignment – Due Monday, Dec 5/11

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