PEE

• Population

  Number of species, organisms in a particular place
• Population Ecology

  Major characteristics:

  Population size

  Population density

  Population dispersion

  Age distribution

  Natality

  Mortality
• Age distribution

  This refers to the proportions of individuals of each age which is often based on non-reproductive ages, reproductive ages and post-reproductive ages
• Natality

  This refers to the ability of the population to give rise to new offspring. This rate is equivalent to the birth rate in human demographic studies.

  it is an expression of the production of new individuals in the population by birth, hatching, germination or fission.
• Potential Natality - the maximum number of births produced per individual under ideal conditions of environment. It is also called reproductive or biotic potential, absolute natality or maximum natality.
• ➤ The maximum or absolute natality is observed when the species exists under ideal ecological and genetic conditions. ➤ The actual number of births occurring under the existing environmental conditions is much less as compared to absolute natality. It is referred to as Ecological natality or realized natality.
• Characteristics of Population

  1. Population Size. This refers to number of individuals. This is an important feature of any population and affects ability of population to survive. Small population tends to become extinct or endangered by random events such as inbreeding.

  2. Population Density. This refers to the number of individuals in a certain area or volume. This is important to survival of population.

  ➤ It is generally expressed as the number of individuals or the population biomass per unit area or volume.

  ➤ Population density can be calculated by the following equation:

  Dp = N/A
• Population dispersion. This refers to the way in which individuals of a population are spaced within their area or volume. This often depends on resource availability of spatial pattern.
• Mortality.This is the death rate of the individuals in the population. Like natality this is equivalent to death rate in human populations.
• Ecosystem

  • a community of living organisms in a particular area.
  • place, area, geographic area
  • living things, non living things
  • all things interact
• Ecology

  a study of the relationship between living organisms, including humans, and their physical environment.
• Components of Ecosystem

  • Biotic
  • Abiotic
• 4 laws of ecology

  • Everything is connected to everything - law of interrelatedness
  • Everything must go somewhere - earth is a close system ,, ang lahat ng bagay ay may hahantungan.
  • Nature knows best
  • There's no such thing as a free lunch
• Types of Population Density a. Crude Density is the density per unit of total space. Generally, populations be habitable. do not occupy all the space as whole because all area may not b. Specific (or Ecological) Density- is the density per unit of habitable space. It includes only the portion of total space that can be colonized by the population.
• There are 3 main patterns of dispersion.

  Clumped dispersion. This is a pattern when individuals clump into groups or cluster often in response to uneven distribution of resources. This is the most common pattern in nature.
• 3 patterns of dispersion

  Uniform Dispersion. This is the pattern when individuals are uniformly or evenly spaced often as a result from interactions between individuals. This is relatively common in nature. Random dispersion. This is the pattern when individuals are spaced in a patternless, unpredictable way and don't interact strongly with one another. This is not common in nature.
• TYPES OF MORTALITY a. Ecological or realized mortality is the number of individuals lost in a given environmental condition.

  
  

  b. Minimum Mortality refers to the minimum loss under ideal conditions of environment. This value is constant for a population and is often determined by physiological longevity. This value is often larger than ecological longevity.
• Natality varies from organism to organism. It depends upon the population density and environmental factors. ➤ If the population density is low, the birth rate is also low. ➤ If the population density is unusually high, the birth rate may also be low due to poor nutrition or physiological and psychological problems related to crowding.