ADAPTATIONAP 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

• 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 textKnow this as an example