Understanding the Diversity of Life Part 2

Understanding the Diversity of LifePart 2

EVOLUTION & SPECIATION1

1

MODERN EVOLUTIONARY THEORY

•By combining the work of Charles Darwin with modern genetics, evolutionary biologists have a much better understanding of how evolution works

2


•What is a population?

•What is a gene pool?

• Group of individuals of the same species that interbreed

• All of the genes that a population has in common

3


•What is relative frequency?

• In genetic terms, evolution is…

• How often an allele occurs in a gene pool

• any change in relative frequency of alleles in a population

4


• What are the 2 main sources of genetic variation

1. Mutations

2. Gene Shuffling

5


•What is a mutation ?•Why does a

mutation occur?

• Change in DNA sequence

•Mistakes in replication • Exposure to

radiation • Chemicals in the

environment 6


•What is gene shuffling?

•What happens during gene shuffling?

• Distribution of different alleles during meiosis

• Each new gamete gets a different set of alleles

7

BEYOND MUTATIONS & GENE SHUFFLING

• Non-random mating is…

• Examples:

• Results:

• Some members of the population have more opportunity to mate than others

• Fighting (lions & walrus)• Dances/songs (birds)

• Better fighters/dancers mate with more females

8


• Gene flow is…

• Gene flow has…

• Why?

• Gain or loss of genes as organisms move in and out of populations

• Less effect on large populations

• Genes are diluted by large pool

9


• Genetic Drift is…

• Occurs more often in…

•Why?

• Random change in allele frequency causes an allele to become more common

• Small populations

• Fewer alleles to counteract affects

10

BEYOND MUTATIONS & GENE SHUFFLING• Types of genetic drift:1. Bottleneck effect –

happens due to…

Examples:

• Catastrophic events• Random survivors whose

genes do not reflect original population

• Bald Eagle• American Bison

11


1963 – 417 mating pairsDDT Buildup

1890’s – 750 animalsOverhunting

12


• Types of genetic drift:2. Founder effect -

happens when…

Examples:

• A few organisms from a larger population are transferred to another location

• Darwin’s Finches• Seeds carried by

wind/water13

SPECIATION15

SPECIATION• What is a species?

• What is speciation?

• A group of organisms capable of interbreeding and producing fertile offspring

• A change in organisms that leads to new species

16

SPECIATION• How does speciation

happen?• Organisms from a

population must be reproductively isolated from each other

17

SPECIATION• Geographic isolation

leads to speciation because…

• Examples:

• It puts a physical barrier between members of a population

• Earthquakes• Mountain ranges• Human activity

18

SPECIATION• Behavioral isolation


• Geographically isolated members of a population develop new mating behaviors

19

SPECIATION• Temporal isolation


• Members of a population start to reproduce at different times

20

PATTERNS OF EVOLUTION

21

MACROEVOLUTION• What is

macroevolution?• Large-scale history of

life on earth

22

MACROEVOLUTION

1. Extinction is…

• Extinction happens because…

• The complete loss of a species from Earth• Organisms are unable

to adapt to changes in the environment

23

MACROEVOLUTION

2. Adaptive radiation is…• Adaptive radiation

happens when…• Example:

• Evolution of one species into several species• A species moves into a

new, unoccupied region• Darwin’s Finches

24

MACROEVOLUTION

3. Coevolution is…

• Examples:

• The evolution of 2 different species due to their interactions with each other• Mutualism• Predator-Prey• Parasitism

25

MACROEVOLUTION

4. Convergent evolution is…

• These structures are called…

• Convergent evolution happens because…

• The development of body structures with similar functions that are structurally different• Analogous structures

• Vastly different organisms face similar environmental demands

26

MACROEVOLUTION• Examples of

convergent evolution in organisms:• Birds• Bats• Bugs

27

MACROEVOLUTION

5. What are Hox genes?

• Where are Hox genes found?

• Why are Hox genes important?

• A specific sequence of nucleotides about 180 units long• In the DNA of most

animals• They are the master

genes that control embryological development of body plans 28

MACROEVOLUTION6. Punctuated equilibrium is…

• Punctuated equilibrium occurs after…

• Example…

• Rapid period of speciation between long periods of stability

• A catastrophic event• Some sort of massive

mutation occurs in a gene pool• Cambrian Explosion

30

MACROEVOLUTIONCatastrophic Event Massive Mutation in Gene Pool

31

Understanding the Diversity of Life Part 2

Documents

Transcript of Understanding the Diversity of Life Part 2