4.1 Species and Communities

• Species - a group of organisms that can interbreed and produce fertile offspring
• Ecosystem - A group of populations interacting with each other and the abiotic environment
• Autotrophic - an organism that uses solar energy or chemical energy to manufacture the organic compounds it needs as nutrients from simple inorganic compounds obtained from its environment
• Detritivore - heterotrophs that obtain organic nutrients from detritus by internal digestion.
• Saprotrophs - heterotrophs that obtain organic nutrients from dead organisms by external digestion.
• A community - A group of populations of different species living together in the same area
• Population - all individuals of one species occupying a particular area at any given time
• Example of a detritivore -  A dung beetle that feeds by ingesting the droppings of different animal species and digesting its food internally
• Decomposition - the primary process by which nutrients are recycled in an ecosystem
• The most important factors for maintaining sustainability in an ecosystem is nutrients are recycled
• Sampling is necessary in collecting ecological data because it is used to make inferences about a larger population based on a smaller sample size
• The chi-squared test is used to determine whether the observed data differs significantly from the expected data
• Species - a groups of organisms that can potentially interbreed to produce fertile offspring.
• Habitat - the natural home or environment of an

  animal, plant, or other organism.
• Population - the number of members of one species in one place at one time.
• Reproductively Isolated populations are unable to reproduce with other populations, and therefore evolve in different ways.
• A community forms an ecosystem by its interactions with the abiotic

  environment.
• Nutrition – is the process of obtaining the food necessary for health and growth.
• Autotrophs - organisms that are able to form nutritional organic substances (food) from simple inorganic substances such as carbon dioxide.
• Producer - organisms that are able to form nutritional organic substances (food) from simple inorganic substances such as carbon dioxide.
• Abiotic (environment) - physical rather than biological; not derived from living organisms.
• Biotic - relating to or resulting from living organisms.
• Consumer - organisms that are heterotrophs which feed on living (or recently living)organisms, by ingestion.
• A primary consumer is an organism (usually an animal) that feeds on producers (autotrophs).
• A Secondary Consumer is an organism (usually an animal) that feeds on primary consumers.
• Tertiary Consumer is an organism (usually an animal) that feeds on secondary consumers.
• Detritivores are heterotrophs that obtain organic nutrients (food) from detritus (dead organisms) by internal digestion.
• Detritivores are heterotrophs that obtain organic nutrients (food) from detritus (dead organisms) by internal digestion.
• Detritus – is dead organic matter that can be dead parts of plants, feathers, hair or other parts of animals, and feces
• Species will typically show a negative association if there

  is competition for the same resources:

  • One species may utilise the resources more efficiently,

  precluding survival of the other species (competitive

  exclusion).

  • Both species may alter their use of the environment to avoid

  direct competition (resource partitioning).
• A quadrat is a rectangular frame of known dimensions that

  can be used to establish population densities.

  Quadrat sampling is not an effective method for counting

  motile organisms – it is used for counting plants and sessile

  (stationary) animals.
• Expected Value = (Row Total x Column Total)/ Grand Total