1. Speciation Macroevolution

2. Speciation Species:   groups that can reproduce with each other and produce viable offspring Speciation:   origin of a new species   leads to greater diversity Macroevolution:   origin and extinction of different species, evolution of new features eg. wings

3. Reproductive Isolation   the inability of a sp. to breed with another   results from barriers, either physical (ex mtns) or behavioural (ex. mating dance).   sp. do not breed with each other in nature (even if they are capable of it)   various types:

4. 1. Geographic Isolation   Landforms, water, distance to move (or spread repro. cells) limits reproduction Genetic drift and natural selection work together to form unique species. For every species that forms, many more perish ex.Harris’s antelope squirrel and white-tailed antelope squirrel divided by the Grand Canyon

5. 2. Habitat Isolation some species have adapted to a specific location within an ecosystem. even though contact is possible, preferences for their habitat prevents it ex. 2 sp of garter snakes live in same area 1 sp lives mainly in water, other on land so don’t interact

6. Other Reproductive Barriers A. A. Temporal isolation - different breeding seasons B. B. Behavioural isolation - different mating behaviours C. C. Mechanical isolation - different reproductive structures D. D. Gamete isolation - different sex cells E. E. Hybrid inviability - hybrids are not healthy enough to survive or reproduce F. F. Hybrid infertility - hybrids born healthy, but are unable to reproduce

8. Adaptive Radiation   Divergent Evolution   organisms arrive in different environment   new habitats encourage speciation Founder effect + natural selection + reproductive isolation = speciation   evolution from a common ancestor results in diverse species adapted to different environments

9. Convergent Evolution   distantly related species living in similar environments develop similar adaptations   face similar selection pressures North American antelope (left) and African impala antelope (right) appear to be very closely related, but have actually evolved convergently to resemble each other.

10. Rate of Speciation Gradualism:   evolution of a species by gradual accumulation of small genetic changes over a long period of time   Darwin knew geologic changes occurred very slowly, believed speciation must evolve in same way Punctuated Equilibrium:   changes to a species can occur suddenly, and can be extensive enough to create a new species in a short period of time   fossil record shows many new species appearing abruptly

11.   both can occur as a result of Natural Selection

12. Human Activity   usually results in a decrease of biodiversity   island ecosystems at risk   ex dodo   ecosystems affected by human activity and introduction of invasive species   modern agriculture and fishing