1. Evolution of Biodiversity
Chapter 5
Evolution of Biodiversity

2. The Dung of the Devil
 Spanish flu- unprecedented flu outbreak
Mortality estimates vary 20 mil – 100 mil worldwide
In China – found the roots of a particular plant with beneficial properties to fight the flu (Ferula assafoetida )
H1N1 virus caused Spanish flu – similar to H1N1 that caused the “swine flu” outbreak
Other organisms we have extracted life-saving drugs from:
Of most promising current candidates for new drugs – 70% were first discovered in plants, animals and microbes
Problem?
Why talk about this?

3. Earth is home to a tremendous diversity of species
Ecosystem diversity- the variety of ecosystems within a given _______
Species diversity- the variety of species in a given ______________
Genetic diversity- the variety of genes within a given ____________
Diversity among individuals
**All three scales of biodiversity contribute to the overall biodiversity of the planet**

4. How many species live on Earth?
Species – a group of organisms that is distinct from other groups in terms of size, shape, behavior or biogeochemical properties
Must be able to …
Problems estimating population size
To date: approximately 2 millions species named
Current estimates for total number of species million

5. Definitions 2 measure to help determine diversity: Species richness-
Species evenness-
Must evaluate together

6. Determining Evolutionary Relationships Among Species
Phylogenies – branching patterns of evolutionary relationships
Can be described in a diagram  phylogenetic tree

7. Evolution is the Mechanism Underlying Biodiversity
Evolution- a change in the genetic composition of a population over time
Occurs at multiple levels (remember KPCOFGS):
Microevolution
Macroevolution
Speciation
Depends on genetic diversity

8. Creating Genetic Diversity
Genes- physical locations on chromosomes within each cell of an organism
Genotype- the complete set of genes in an individual
2 processes that create genetic diversity (occur over an organism’s lifetime):
Mutation-
Caused by:
Must occur where in order to be passed on?
Recombination – when chromosomes are duplicated during meiosis

9. Creating Genetic Diversity
Phenotype- the actual set of traits expressed in an individual
Includes: anatomy, physiology and behavior
Effected by both:

10. Evolution occurs by… Artificial selection Natural selection
Random processes

11. Evolution by Artificial Selection
Evolution by artificial selection- when humans determine which individuals breed
Selecting for desired traits
Examples:
Unintended consequences:
Resistance!!

12. Evolution by Natural Selection
Evolution by natural selection- the environment determines which individuals are most likely to survive and reproduce
Adaptations –

13. Darwin’s theory of evolution by natural selection
Individuals produce an excess of offspring.
Not all offspring can survive.
Differences in traits can be passed on from parents to offspring.
Differences in traits are associated with differences in the ability to survive and reproduce.

14. Evolution by Random Processes
Random processes (does not relate to a change in fitness):
Mutation- occur randomly and can add to the genetic variation of a population
Genetic drift-
Bottleneck effect- a reduction in the genetic diversity of a population caused by a reduction in its size
Founder effect-

16. Speciation and extinction determine biodiversity
Moving from microevolution to macroevolution:
Allopatric speciation-
Ways to create a new species:
Geographic isolation – due to founder effect
Reproductive isolation –can no longer interbreed and produce viable offspring
Example: Darwin’s Finches
More common method of speciation

17. Speciation and extinction determine biodiversity
Sympatric speciation- the evolution of one species into two species in the absence of geographic isolation, usually through the process of polyploidy, an increase in the number of sets of chromosomes
Result of _______________________ vv– increase in the number of chromosomes
Polyploid organisms cannot interbreed with diploid ancestors

18. The pace of evolution Long time  hundreds to millions of years
Influence of 4 factors on successful adaptation:
a – rate of environmental change
b – genetic variation
c – population size
d – generation time

19. The pace of evolution
Evolution by artificial selection is faster than by natural selection
Evolution occurs more rapidly in populations of GMOs
Genetic engineering –

20. Evolution shapes ecological niches and determines species distributions
Range of tolerance- the limit to the abiotic conditions organisms can tolerate
However, all species have an optimal environment
Fundamental niche- the ideal conditions for a species

21. Niches
Realized niche- the range of abiotic and biotic conditions under which a species lives
Determines the species distribution Niche generalist- species that live under a wide range of conditions
Niche specialist-

22. Environmental change and species distributions
Species vary in ability to adapt
Move physically

23. Predicting future species distributions
We try to predict how distributions might change as a result of future changes in environmental conditions

24. Environmental changes and species extinction
Species that cannot adapt to changes go extinct
99% of all species that have ever lived on Earth are now extinct
Why do species go extinct?

25. The Fossil Record So how do we know about evolution of life? Fossils-
Oldest fossils are found further down in sediment  can estimate age of fossils
Most organisms do not become fossils

26. The Five Global Mass Extinctions
Mass extinction- when large numbers of species went extinct over a relatively short period of time
5 global mass extinctions:
251 million ya – 90% of marine species and 70% of land vertebrates went extinct
65 million ya – ½ of Earth’s species (including dinosaurs) went extinct

27. The Sixth Mass Extinction
Scientists feel that we are in our sixth mass extinction, occurring in the last two decades
In contrast to previous mass extinctions, scientists agree that this one is caused by ______________________________
Including: habitat destruction, overharvesting, introductions of invasive species, climate change, and emerging diseases