Tag Archives: abundance

Chapter 9: Habitats, environment and survival


Author’s photo taken at the Leaning Trees of Greenough, Western Australia

Learning Intention: Students will understand the biotic and abiotic factors that affect the distribution and abundance of organisms on earth.

Success Criteria: Students will successfully complete the Chapter 9 review questions and be able to list biotic and abiotic factors that affect the survival of organisms on earth.

Buffeted by the prevailing southerly winds, these eucalypts have survived despite challenging conditions. The survival of organisms, and therefore their distribuition and abundance, depends on both biotic (living – predators, competitors, pathogens, parasites) and abiotic (physical – temperature, wind speed, pH, atmospheric gases, turbidity, salinity, solar radiation) factors. This chapter of work is about habitats and the factors that affect the survival of organisms in their environments. Learn some definitions for this chapter at Chapter 9: Habitat and Survival Flashcards.  You will also learn about niches and resource use graphs. Match some Australian species to their habitats at DECC.

Living organisms survive in their environments due to structual, functional and behavioural adaptations. Evolution is the process by which living organisms have changed over thousands of years to become more suited to their environments. Google ‘evolution’ and you will find an enormous selection of contradictory articles confirming or condemning “The Theory of Evolution”, first proposed by Charles Darwin in 1859.

To summarise Darwin’s Theory of Evolution;

1. Variation: There is variation in every population.
2. Competition: Organisms compete for limited resources.
3. Offspring: Organisms produce more offspring than can survive.
4. Genetics: Organisms pass genetic traits on to their offspring.
5. Natural Selection: Those organisms with the most beneficial traits are more likely to survive and reproduce.