Principle of Competitive Exclusion or Gause’s Principle

No two species can coexist and share the same spaceif they compete for the same resources within that space

Coexistence possible only if resource needs do not overlapor only slightly overlap

Niche

All ecological parameters under which a species lives and grows

--abiotic and biotic resources

No two species can share the same niche

Resource partitioning

Character displacement

When related species coexist by exhibiting differencesin morphology of one or more characters that reducesniche overlap

e.g., beak size and seed size in birds

A morphological character is part of the phenotype of a species, often (but not always) determined by genotype

Adaptive Radiation

Figure B, p. 283