Organisms And Populations

Step 1: Understanding the Concept:
Organisms use various morphological adaptations to protect themselves from predators or to hide from prey.
Step 2: Detailed Explanation:
Camouflage is an adaptation where an organism blends into its surrounding environment using colors or patterns.
Examples include leaf insects or stick insects that look exactly like their surroundings.
Mimicry is different; it involves one species evolving to look like another species (the "model") to gain protection.
Warning Colouration (Aposematism) involves using bright, high-contrast colors to signal to predators that the organism is toxic or distasteful.
Step 3: Final Answer:
Resemblance to the environment for the purpose of hiding is defined as camouflage.

Step 1: Understanding the Concept:
In community ecology, the "niche" of a species includes all the resources it uses and the conditions it requires.
When two species have significantly overlapping niches—meaning they require the same limited resources like food, nesting sites, or sunlight—competition arises.
Russian ecologist G.F. Gause formulated a principle to describe the outcome of such intense competition.
Step 2: Detailed Explanation:
The principle is built on several key ecological premises:
1. Resource Limitation: The principle is most applicable when resources are "limiting" (not enough to satisfy everyone).
2. Absolute Competitors: If two species are identical in their resource requirements, they are termed "complete competitors."
3. The Outcome of Competition: One species will always possess a slight biological advantage—be it faster reproduction, better foraging efficiency, or higher tolerance to environmental stress.
4. Competitive Exclusion: Over time, the "superior" competitor will out-reproduce the "inferior" one.
5. Extinction: This leads to the eventual local extinction of the inferior species or forces it to migrate to a different habitat.
6. Modern Context (Resource Partitioning): Later studies (like MacArthur's warblers) showed that species can avoid this exclusion by evolving "Resource Partitioning," where they feed at different times or on different parts of the same resource to coexist.
Step 3: Final Answer:
Gause’s principle asserts that in a resource-limited environment, two species cannot occupy the exact same niche; the more efficient species will eventually displace the other.