Postulate of Darwin

Geometric increase 

Limited food & Space

Struggle for existence 

Variation 

 Natural selection

Inheritance of useful characters

Speciation

TLS Online TPP Program

#Id: 5723

#Unit 10. Ecological Principles

Species-Time Hypothesis 

Communities diversify, that is, gain species, with time

Temperate regions are less species-rich than tropical regions because they are younger and have only more recently recovered from glaciations and severe climatic disruption

TLS Online TPP Program

#Id: 5724

#Unit 10. Ecological Principles

TLS Online TPP Program

#Id: 5725

#Unit 10. Ecological Principles

The Species-Area Hypothesis Large areas contain more species than small areas because they can support larger populations and a greater range of habitats.

TLS Online TPP Program

#Id: 5726

#Unit 10. Ecological Principles

TLS Online TPP Program

#Id: 5727

#Unit 10. Ecological Principles

The Species-Energy Hypothesis

Available energy determines species richness.

Increased solar energy, together with an abundance of water, results in high productivity of plants.

TLS Online TPP Program

#Id: 5728

#Unit 10. Ecological Principles

The evapotranspiration rate is in turn influenced by the amount of solar energy and the amount of water in the ground.