Unit 3: Populations

• Specialists

  • Smaller range of tolerance or narrower ecological niches make them MORE prone to extinction
  • Specific food requirements
  • Less ability to adapt to new conditions
• Generalists

  • A larger range of tolerance or broader niche makes them less prone to extinction
  • Broad food requirement
  • High level of adaptability
  • More likely to be invasive
  • Very competitive
• Generalists are far more likely to be invasive whereas specialists are more likely to be disturbed by invasive species
• Koalas are specialists because they ONLY feed on the leaves of the eucalyptus tree; raccoons are generalists because they live in many environments and are omnivores
• Specialists

  • Narrow niche
  • Less adaptable because of special needs
  • More likely to extinct
  • Use a specific set of resources
  • Easily affected by changing environment
  • Advantaged when conditions are CONSTANT
• Generalists

  • Broad niche
  • Adaptable to many environments
  • Less likely to become extinct
  • Uses a variety of resources
  • High range of tolerance
  • Have an advantage when conditions CHANGE
• K-selected and r-selected are types of reproductive strategies
• K-Selected Species

  • "Quality over quantity"
  • Produce fewer offspring and will provide heavy parental care to protect them
  • Usually reproduce many times, so parents invest a lot of energy in them
• K-Selected Species

  • Long lifespan and long time to reach sexual maturity
  • Long sexual maturity = low biotic potential = slow population growth rate
• K-Selected species

  As a result of low population growth, they're more likely to be disturbed by environmental changes
• R-Selected Species

  • "Quantity over quality"
  • Produce MANY offspring, so they don't provide much parental care
  • MAY only reproduce once, so they make that shot worth it
  • Shorter lifespan and quick to reach sexual maturity
• R-Selected Species

  • Quick sexual maturity = high biotic potential = high population growth rate
• Based on the chart, is the blue whale a k-selected or r-selected species?

  K-selected

  
• Reproductive strategies (k/r-selected) and organism type are all spectrums
• K-Selected

  • Low biotic potential = hard for the population to recover after a disturbance
  • High parental care means death of parent leads to the death of vulnerable offspring
• Invasive species (USUALLY r-selected) outcompete for resources with their high biotic potential and rapid population growth
• R-selected

  • High biotic potential = more rapid population recovery after disturbance
  • Low parental care means the death of a parent doesn't impact the offspring
  • More likely to be invasive as it's a larger population with faster generation time that gives them a higher chance of adapting and lowers chances of extinction
• A survivorship curve is a line that displays the relative survival rates of a cohort in a population from birth to max age reached by any cohort member
• • A faster drop in line = quicker die-off of individuals
  • A slower drop in line = longer average lifespan
  • The age is relative to an organism's age
• Type I Survivorship (K-Selected)

  • High survivorship early life due to high parental care
  • High survivorship in mid-life due to large size and defensive behavior
  • Rapid decrease in survivorship in late life as old age sets in
  • Ex. Most mammals
• Type II Survivorship (In between r and k-selected)

  • Steadily decreasing survivorship throughout life
  • Some parental care; usually small
  • Ex. rodents, birds, insects, amphibians
• Type III Survivorship (r-selected)

  • High mortality (Low survivorship) early in life due to little to no parental care
  • Few make it to mid-life; there is a slow, steady decline in survivorship in mid-life
  • R-selected individuals balance mortality rate by having lots of offspring
• • Carrying capacity is like the maximum restaurant occupancy
  • Each restaurant has a capacity based on space, food, and servers
  • Likewise, carrying capacity for each species based on resource availability
  • Carrying capacity is DIFFERENT for each species as they have different needs
• Carrying capacity (k) is the maximum number of individuals in a population that an ecosystem can support based on limited resources
• Carrying capacity is the highest population size an ecosystem can support based on limited resources. Name 3.

  Food, shelter, and water
• Overshoot occurs when a population briefly exceeds carrying capacity

  
• "Consequence of Overshoot" occurs when resources are depleted as there's too many organisms
• 1. Deer breed in the fall and give birth ALL at once in spring
  2. Overgrazing of deer
  3. Many deer starve with too many new fawns feeding in spring

  What process is illustrated by number one?

  Overshoot
• 1. Deer breed in the fall, and give birth ALL at once in spring
  2. Overgrazing of deer
  3. Many deer starve with too many new fawns feeding in spring

  What process is illustrated by number two?

  Consequence of overshoot
• 1. Deer breed in the fall, and give birth ALL at once in spring
  2. Overgrazing of deer
  3. Many deer starve with too many new fawns feeding in spring

  What process is illustrated by number three?

  Die-off
• Die-off is a sharp decrease in population size when resource depletion (overshoot) leads to many individuals dying

  
• Carrying capacity can also be impacted by predator-prey relationships

  
• • Type II species many insects like butterflies, fish, and amphibians
• Type III species include trees
• What type of survivorship curve is independent of age at ANY TIME; the same rate of species are surviving and dying REGARDLESS of age?

  Type II
• A TEMPORARY decline in carrying capacity must be due to a temporary condition such as a drought
• Food source EXTINCTION, invasive species, and intense competition lead to PERMANENT reduce in carrying capacity
• A slower drop in life means ____ lifespan?

  longer
• Population Characteristics: Size (N)

  • Total number of individuals in a given area at a given time
  • The larger the size, the safer from population decline
• Population Characteristics: Density

  • Number of individuals per unit of area
  • The higher the density, the higher the competition and the possibility of disease outbreak
  • The possibility of depleting food sources is higher
  • Ex. 12 panthers/km^2