• Need to study reproduction: number of offspring

Steady State of Natural Populations

• Need to study population-level processes, such as rate of population growth, mortality, immigration, emmigration, etc.

Limited Resources

• Need to study how individuals get the resources they need
  • for survival
  • for reproduction
• Need to study interactions that may limit availability of resources for some individuals

Variation

• What characteristics are variable?
• What variation is genetically determined and, therefore, heritable?

Struggle for Existence

• What features of a plant affect survival and lifetime reproductive output?
• What is the relative value of different homologous character states?

Natural Selection

• To what degree are different characteristics removed from a popoulation due to their reduced ability to survive and reproduce?