Download Introduced Species

ADAP
TATION
AP Env Sci 2011-2012
Natural Selection
• Predation, competition keep populations in check
• Adaptation may result from intraspecific or interspecific
competition
• Intraspecific competition:
– Improved adaptation of species to environment
• Interspecific competition
– Specialization -> resource partitioning
Selective Pressure
• Every factor of Environmental Resistance is a
Selective Pressure “selecting” those individuals
who can cope with surroundings
• Let’s name a few….
Five Types of Adaptation
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Climate/abiotic factors
Obtaining food/water/nutrients
Escape or protection from predators
Finding or attracting mates
Migration or seed dispersal
• More Examples?
Three Possible Responses to New Pressure:
• Adaptation
• Migration
• Extinction
• For adaptations to occur, there must be some
individuals with the desired traits
– “fish gotta fly, birds gotta swim”
Keys to Survival: Housefly vs. Condor
• Geographical Distribution: world vs. certain locations
• Specialization in Habitat or Food: any vs. mountain, ravine
• Genetic Variation: many generations/yr vs. 1-2 chicks/yr
• Reproductive Rate vs. Rate of Environmental Change: many
generations/year vs. one generation/year
In the Book…
Speciation
• As many as 14 million species may exist on Earth
• One species -> Two species What is Needed?
– Reproductive Isolation
– Different Selective Pressures
• Example: Arctic Fox vs. Grey Fox
Figure 4-17 in text
Know this as an example