Distribution and abundance 2

• Distribution Patterns

  • Random
  • Uniform (Regular)
  • Clumped
• What distribution includes

  • Where a species lives
  • Habitat
  • Geographic range
• Most vertebrate species range < 10,000 km^2
• Scale

  The size or level of something
• Density = total number of individuals within a given area or volume
• What do we mean by distribution?
• Spatial scale


  • Area (L x B, m^2)
• Distribution of a species varies at different spatial scales
• Ecology


  Coined by Ernst Haeckel in 1866, Greek: οἶκος, "house", -λογία, "study of"
• Distribution influenced by available habitat
• Distribution


  The geographic range of a group/taxon/lineage. It also includes the spatial pattern or arrangement of members of a population
• Abundance data is used to reflect both population distribution and density
• Range


  The limits of the geographic distribution of a group/taxon
• Riverine rabbit is critically endangered in the Karoo Region of SA
• Factors influencing distribution

  • Temperature
  • Red Maple
  • Carolina wren
• Speaker: 'Welcome to the BIOL305 module!!!'
• Ecology is the study of the distribution and abundance of organisms, the interaction between organisms, the interaction between organisms and their environment, and structure and function of ecosystems
• Abundance is the number of animals/plants
• Species with continental level range are critically endangered with around 5,600 individuals
• Abundance = total number of individuals of a taxon (species) in a population
• Canadian mammals have large ranges, while Mexican mammals have smaller ranges
• Clumped distribution pattern
• Species at high latitudes (or altitudes) develop a broader thermo-tolerance range and become more extensively distributed than species at low latitudes (or altitudes)
• Rapoport’s Rule states that geographic ranges decrease from the poles to the equator
• Conclusion: Distribution and range, abundance and density, distribution patterns, most species have small or large ranges, range sizes change with geography, Rapoport’s Rule, Climatic Variability Hypothesis
• Grizzly bear is a species
• Grayish mouse opossum is a species
• Most vertebrate species range less than 10,000 km²
• Climatic Variability Hypothesis (CVH): Terrestrial organisms in highly variable environments are adapted to withstand a broader range of climatic conditions
• Riverine rabbit is critically endangered in the Karoo Region of South Africa
• Individuals avoid one another
• Rapoport’s Rule holds for many trees, fishes, reptiles, some birds, and mammals on most continents
• Distribution and range

  1. Abundance and density

  2. Distribution patterns
• Rapoport’s Rule
• Do range sizes change with geography?
• Is range size positively related with abundance?
• Sampling Model


  1. Purely an artifact of sampling

  2. Why distribution and abundance are correlated
• Population


  Group of individuals, all of the same species, that live in the same place
• Some bird species appear to be declining (abundance) based on breeding bird survey routes
• Population Ecology: the branch of ecology that studies the structure and dynamics of populations