1. Balance Between Speciation and extinction
Biodiversity
Balance
Between
Speciation and extinction

2. What is biodiversity? Type 1: Total number of species in world
Type 2: Genetic variation within and between species.
Type 3: Ecosystem biodiversity: huge variety of ecosystems and habitats

3. Total number of species
What patterns do you see?
How do you think scientists estimate the ``unnamed species’’?

4. Genetic biodiversity
                                      European sheep breeders protecting genetic diversity of their breeds.
These are all one species

5. These are all different species

6. Genetic biodiversity
For example, humans are one species, but we have a great variety of variation in many genes, such as blood type
Each species has thousands of genes

7. Ecosystem biodiversity

8. What is an ecosystem??
A community of organisms, its abiotic environment, and their interactions

9. Levels of ecological organization
Biosphere: all life on Earth and the life-supporting region of Earth
Ecosystem
Community?
Populations of different species in the same area or habitat
Population?
Group of individuals of same species in same area or habitat

10. Origin of biodiversity
EVOLUTION
Simple definition:
Descent with modification
Includes microevolution: changes in gene frequency from one generation to the next
Includes macroevolution: descent of different species from a common ancestor

11. Natural Selection Darwin’s big contribution Inherently logical:
Organisms produce more offspring than survive
Individuals vary in important characteristics
Many characteristics are inherited
SO:
some individuals will be better suited to the environment
Those individuals will be more likely to survive and reproduce
Their offspring likely to be more suited to the environment

12. Definition of evolution
Descent with modification
KEY: Evolution proceeds by changes in genes
NOT JUST: ``Change over time’’
Lots of things change over time:
Trees change color
Mountains erode
Continents move
These are NOT evolution

13. Evolution is NOT Just a process of getting better
Something that organisms TRY to do

14. Geneology: sharing a common ancestor

15. Evolution: sharing a common ancestor

16. Natural Selection Darwin’s big idea HOW evolution can happen
Follows logically from some simple ideas:

17. Logic of natural selection
Organisms produce more offspring than can survive.
Even elephants—if all survived . . .
Often, these differences are due to differences in the genes and therefore can be inherited

18. Logic of natural selection
Individuals vary in their characteristics

19. Logic of natural selection
Often, these differences are due to differences in the genes and therefore can be inherited

20. Logic of natural selection -2
As a result of individuals inheriting characteristics from parents:
Some individuals will be better suited to their environment than others
These better-suited individuals produce more offspring that survive
They may survive longer to reproduce
They may produce more offspring
They may produce offspring of higher quality

21. Logic of natural selection - 3
As a result of some individuals producing more fit offspring:
Future generations will contain more genes, and more characteristics, of the better-suited individuals.
Better suited are called ``more fit’’

22. Natural selection doesn’t mean:
Only the strong survive NO
Sometimes, other ways of being fit (e.g., hiding)
Only the best-suited individuals survive NO
Many types may survive. Over long periods, the more fit will leave more offspring.

23. Natural Selection
Often MIScharacterized as ``evolution by random chance’’
What IS random about natural selection?
The production of variation by mutation and genetic recombination

24. Adaptations Traits that are successful in their environment
An adaptation to one environment may be NEUTRAL or UNFAVORABLE in another environment
May be simple—heavier coat in colder climate—or complex—the mammalian eye

25. Again: Adaptations are specific to the environment.
A zebra’s coat pattern is camouflage in the African savannah. It would not be advantageous in a North American grassland.
Running speed is advantageous for a cheetah on the savannah. But cats in the rainforest (e.g., jaguar) are not fast. Strength and stealth are more important than speed there.

28. Adaptation examples: mimicry
                                                                
Adaptation examples: mimicry
Some orchids have evolved to mimic wasps, fooling other wasps to ``mate’’ with them and thus transfer their pollen

29. Adaptation examples: more mimicry
Katydids have evolved a body form that looks like a leaf.
Why? What is the advantage to the katydid?

30. Adaptation examples: still more mimicry
Non-poisonous king snakes mimic poisonous coral snakes
Many examples of mimicry in nature
                                                                  

31. Speciation One species evolves into another OR splits into two.
How can this happen?
Geographic isolationallopatric speciation

34. History of life As previous picture shows:
Complex creatures and structures have evolved
But simple life forms still common and dominate in many habitats ``Earth still belongs to the bacteria’’
Speciation generates diversity; extinction reduces it

35. Extinction The disappearance of a species from Earth
Local disappearance is called extirpation