Module 4

• Habitat

  Place where organisms usually lives
• Population

  All members of a species that live in a particular habitat
• Community

  Populations of different spices lving in the same place at the same time
• Niche

  An organisms role within its environment
• Ecosystem

  A combination of all the abiotic and biotic factors in a particular area
• Dynamic

  Influencing by changing populations, physical environments etc
• What is the initial growth rate of a population in a new environment according to the logistic model?

  Slow growth rate due to small population and low number of total offspring produced
• What happens to the growth rate of a population as it increases in size?

  The growth rate increases exponentially because of a larger population producing more total offspring
• What are density-dependent factors that can limit population growth?

  Disease, competition, and predation
• How do density-dependent factors affect population growth?

  They slow or decrease population growth, even though the population size may still increase
• What happens when a habitat cannot provide enough resources for a growing population?

  The population growth rate decreases
• What does it mean when a population graph plateaus?

  The population has reached its carrying capacity, which it cannot grow above
• What are the key stages of population growth using the logistic model?

  1. Initial slow growth due to small population
  2. Exponential growth as population increases
  3. Influence of density-dependent factors (disease, competition, predation)
  4. Decrease in growth rate as resources become limited
  5. Plateauing at carrying capacity
• Carrying Capacity

  The maximum population size that can be sustained by that specific environment
• Biotic Impact Factors

  • Each organism abundance affects other abundance, different species interact with one another and interaction may be positive, negative or neutral for species
  • Food chain determine negative or positive effect of biotic and abiotic system
  • Living organisms can affect each other by predation and symbiosis but also have an equally profound effect on resources
• Predator/Prey Relationship

  It is a feeding relationship where the predator obtains its food by killing its prey. E.g. spider eating flies
• Factors that affect number of predator/prey populations are:

  • Number of predator competing for the same food
  • Availability of food for the prey
  • Birth and death rate affecting number of females and males
  • Size of ecosystem
  • Movenment between ecosystem
• Consequence for Population (Predictions)

  • Predators affect distribution and abundance of their prey; effect => size of ecosystem, number of shelter sites, birth/death rate and availability of food for prey
  • Population control
  • Natural communities abundance predator and prey fluctuate through time
• Competition

  • Usually for a resource that is limited supply but valuable for survival
  • Involves risk to competitors, the reward must outwight inheret risk
  • Between species for resources affect reproduction and survival rates
  • Different traits may increase or decrease chance of survival for animals; losing might have to learn to adapt
• Intraspecific


  Within a species
• Interspecific

  Between species
• Animal Species

  • Competition maybe for mates, food, shelter or hiding place
  • Animals also possess various defence mechanisms
• Allelopathy

  Biological phenomenon by which an organism produces one or more biochemicals that influence the germination, growth, survival and reproduction of other organisms
• Symbiosis

  Interaction in which two organisms live together in close relationship that is beneficial to at least one of them
• Mutualism


  Associated between organisms of two different species in which they both benefit from it.
• Parasitism


  It is a relationship in which one organism feed on another without killing it, or even necessarily harming it significantly
• Symbiosis Example

  Sharks and Pilot Fish
• Mutualism Example


  Clownfish and Sea Anemone
• Parasitism Examples


  Tapeworm, Fleas and Barnacles
• Commensalism

  One species is benefited whilst the other is not harmed or helped
• Commensalism Example

  Whales And Barnacles
• Niche


  Part of the ecosystem that the organism occupies, no two species can occupy the same niches
• Niche Example

  Miner bird and Galah can occupy same area but have different food and nesting strategies they occupy different niches within the same habitat
• Recent Extinction

  • Continent dried out due to ice age and rainforests contracted due to drying climate
  • Rainforests were contracting - stored moisture and returned moisture to atmosphere
  • Became hotter and drier, fires broke out due to lightning
• Geological Evidence

  • Allows reconstruction of timeline of events
  • Represent the course of changes in geological and fossil deposits

  Banded iron Formations:

  • Form of geochemical evidence found in Aus
  • Earth's atmosphere undergone changes (Anaerobic to Aerobic)
  • Form of iron rich and iron poor sediments
• Palaeontology


  It is the study of fossils
• Palaeontological Evidence

  • Microfossils are the tiny remains of bacteria, protists, fungi, animals and planta
  • Fossils offer clues to selection pressure of living things. E.g. climate and environment at the time
  • Found in sedimentary rocks
• Ice Core Drilling

  • Accumulation of ice layers in places
  • Scientists can drill into ice, extract gases and reconstruct the climate record
  • Increases understanding of past environment
• Dating Fossils

  To establish age of rock or fossil, researchers use some type of clock to determine date it was formed. Geologists commonly use radiometric dating methods, based on natural radioactive decay of certain elements
• Relative Dating


  The process of determining if one rock or geologic event is older or younger than another, without knowing their specific ages (i.e. how many years ago the object was formed)