More Evolution:who, what, how

•Exam key posted on class webpage

•Check out Bonuses on class webpage

Evolution: A species’ genetic component changes as the individuals reproduce. These changes are based on how the DNA changes and who reproduces.

Reproductive success = evolutionary success

Evolution can occur via several processes.One common process is

Natural Selection:Individuals that are most successful at

reproducing will pass on more of their genetic information.

Natural Selection can only occur when both of these conditions are met:•Genetic diversity gives rise to individuals

with different traitsand

•Not all individuals can reproduce equally

Evolution: A species’ genetic component changes as the individuals reproduce. These changes are based on how the DNA changes and who reproduces.

Individuals are selected…

But species evolve via changes in DNA during reproduction.

Who evolves?…Species.

•A population that can produce fertile offspring

•A population that does reproduce

**A population sharing genetic information**

A. harrisi A. leucurus

Fig 24.6

Horse

Mule

Donkey

X

=

Horse

Mule(sterile)

Donkey

X

= So…horses and donkeys are not the same species.

Who evolves?…Species.

•A population that can produce fertile offspring

•A population that does reproduce

**A population sharing genetic information**

A. harrisi A. leucurus

Fig 24.6

How does evolution occur?Fig 22.19

Divergent EvolutionFig 22.19

Fig 22.20

Convergent Evolution

wrong rightEvolution has no goal...no ultimate life form

Natural Selection:Individuals that are most

successful at reproducing will pass on more of their genetic

information.

Environmentalchanges drive evolution.

Fig 25.13

250 mya180 mya

65 mya135 mya current

Plate Tectonics

The environment is in constant flux

Changing environment can separate populations and lead to new species…

Fig 24.5

Flies raised in different environments prefer to mate with individuals

from the same environment...

Separation does not need to be geographic

Fig 24.9

Flies raised in different environments prefer to mate with individuals from the same environment...

Fig 24.9

Three basic types of selection…

• Directional

• Stabilizing

• Disruptive

Next even more Evolution:Types of Selection and Randomness

•Exam key posted on class webpage

•Check out Bonuses on class webpage