Niches

• What is a niche?

  A niche is the unique position occupied by a particular species within a community.
• What does a niche represent?


  A niche represents the sum of an organism’s adaptations, the resources it needs, and the lifestyle to which it is fitted.
• How is the term 'niche' used in ecology?


  In ecology, 'niche' describes the role an organism plays within an ecosystem.
• Why is it insufficient to define an organism's role simply as 'Parasite'?


  Because there are many types of organisms that could fit into a broad category like 'Parasite'.
• What is the modern definition of a niche?


  A niche is the multidimensional summary of tolerances and requirements of a species.
• What types of tolerances can a species have?


  Tolerances can be biotic or abiotic.
• What are some examples of biotic tolerances?


  Range of density of predators, concentrations of allelopathic chemicals, and intensities of competition.
• What are some examples of abiotic tolerances?


  Range of temperatures tolerated and range of pH tolerated.
• What are the requirements of a species?


  Requirements can be abiotic and biotic.
• What are some examples of biotic requirements?


  Availability of prey, appropriate ratios and concentrations of nutrients in food, and presence of pollinators.
• What are some examples of abiotic requirements?


  Presence of suitable habitat features, such as flat rocks for basking.
• How do tolerances and requirements affect a species' survival?


  They determine whether a species can survive in a particular location.
• What is the challenge in visualizing a species' niche?


  It is difficult to imagine or plot more than three factors in a single graph.
• What are the two types of niches?

  • Fundamental niche: theoretical niche without competition.
  • Realised niche: actual niche occupied in a community with competition.
• What is a fundamental niche?


  A fundamental niche is the niche a species occupies in the absence of any interspecific competition.
• What is a realised niche?


  A realised niche is the narrower niche occupied in response to interspecific competition.
• What does the Competitive Exclusion Principle state?


  No two species can occupy exactly the same multidimensional niche in the same community for any length of time.
• What happens when two species occupy similar niches?


  One species will have a slight advantage, leading to the extinction of the second competitor over time.
• What are Paramecium?


  Paramecium are unicellular organisms.
• What does the data in the Paramecium culture table represent?


  The data shows the population of two species of Paramecium over a period of days.
• What should you do after drawing a graph for Paramecium cultures?


  Compare each graph and explain what is happening and why.
• What is the relationship between fundamental niches and competitive coexistence?


  • Fundamental niches can overlap, leading to competitive coexistence.
  • Competition defines a species’ realised niche.
• What can occur as a result of interspecific competition?


  Competitive exclusion can occur, leading to local extinction of one species.
• What is resource partitioning?


  Resource partitioning is the dividing up of each resource by species specialization and adaptation.
• How does resource partitioning allow species to coexist?


  Where realised niches are sufficiently different, potential competitors can coexist by resource partitioning.
• Why is it important to study parasite ecology?


  To understand the many species of parasites, their abundance, their role in human diseases, and insights into evolution.
• What is the estimated number of species of parasites?


  At least half of all species are parasitic.
• How have traditional views of parasites changed?


  Parasites were traditionally considered to play a minor role in ecosystems, but recent studies show their biomass can equal that of predators.
• What are some globally important diseases caused by parasites?


  HIV, malaria, and infections from helminths affect millions of people.
• How do parasites contribute to our understanding of evolution?


  Parasites and hosts often show strong co-evolution, and studying their genomes reveals mechanisms of gene loss and diversification.
• What is the definition of a parasite?


  A parasite is a symbiont that gains benefit in terms of nutrients at the expense of its host.
• What happens to the host in a parasitic relationship?


  The host is harmed as it loses energy or resources.
• How do parasites differ from predators?


  Parasites have a higher reproductive potential than their hosts, while predators tend to have a lower reproductive rate than their prey.
• What type of interaction is parasitism?


  Parasitism is a symbiotic interaction between a parasite and its host (+/-).
• How can definitions of parasites be complicated?


  Some organisms, like oxpeckers, can switch roles between mutualism and parasitism depending on the situation.
• What is an example of a complex parasitic relationship?


  Sawfly larvae can harm poplar trees and have a greater reproductive potential than the tree.
• What is the niche of parasites?


  Parasites tend to have a very narrow, specialized niche as they are very host-specific.
• How do bird lice demonstrate resource partitioning?


  Bird lice are either 'body lice' or 'wing lice', partitioning the resource of the bird's skin and feathers.
• What is the degenerate nature of parasites?


  Many parasites are degenerate, lacking structures and organs found in other organisms due to their reliance on hosts.
• How has the degenerate nature of parasites affected their classification?


  The degenerate nature obscures their evolutionary relationships and made classification difficult until molecular methods were developed.