POPULATION ECOLOGY

• Population Ecology


  A branch of ecology that focuses on the study of populations of organisms and their interactions with the environment
• Population Ecology


  • Involves examining the dynamics of population size, structure, distribution, and the factors that influence these characteristics over time
• Population


  A group of individuals of a single species that live in a particular area and interact with one another
• Population Size


  The number of individuals in a population and understanding the factors that contribute to population growth or decline
• "In population genetics and population ecology, population size (usually denoted N) is the number of individual organisms in a population"
• Factors that determine population change

  • Natality
  • Mortality
  • Migration
• Natality


  The Birthrate, which is the ratio of total live birth to total population in particular area over a specified period of time
• Mortality


  The Death rate, which is the ratio of total numbers of death to the total population
• Migration


  The large-scale movement of members of a species to a different environment
• Immigration


  The numbers of organism moving into area occupied by the population
• Emigration


  The numbers of organism moving out to the area occupied by the population
• Population Density


  The number of individuals of a species per unit area or volume. It provides information about how crowded or dispersed a population is within a particular habitat
• Low Population Density


  • More space, resources; finding mates can be difficult
• High Population Density


  • Finding mates is easier; tends to be more competition; more infectious disease; more vulnerability to predators
• Population Structure


  The composition of a population in terms of age, sex, size, and other demographic characteristics
• Age Structure in Humans

  • Age pyramids. A population with a broad base indicates a high birth rate, while a population with a narrower base suggests lower birth rates
• Sex Ratio in Lions


  • An important aspect of population structure
• Distribution Patterns in Trees


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• Reproductive Status in Sea Turtles

  • Involves monitoring nesting females, assessing the success of hatchlings, and understanding factors affecting survival during different life stages
• Population Distribution


  How individuals within a population are spatially arranged across a given area. The distribution can be clumped, uniform, or random, and understanding these patterns helps ecologists explore the relationships between individuals and their environment
• Population Dispersion


  The pattern of spacing among individuals within the geographic boundaries
• Clumped dispersion


  • Individuals in a population are clustered together, creating some patches with many individuals and some patches with no individuals
• Uniform dispersion


  • Individuals of a population are spaced more or less evenly, maintaining minimum distance from one another
• Random dispersion


  • Individuals are distributed randomly, without a predictable pattern
• Population Regulation


  The ecological processes (biotic and abiotic factors) by which the growth of populations is limited due to the effects on birth and death rates
• Top-down population regulation


  Also known as "predator-controlled" regulation, involves higher trophic level species, such as apex predators, controlling the populations of lower trophic level species, like prey
• Bottom-up population regulation


  Depends on the resources available in an ecosystem. Higher trophic levels rely on the presence of resources from lower trophic levels. Diminished or absent resources at lower trophic levels impact all trophic levels in the ecosystem
• Life History Strategies


  A species' biological characteristics that influence how quickly its population can potentially increase in number. Includes life span, fecundity (number of offspring an organism can produce) or maturity rate
• Life History Traits

  • Size and growth rate of organisms
  • Age at first reproduction
  • Length of time when reproduction is possible (number of reproductive events)
  • Number of offspring produced at each reproductive event
  • Average length of lifespan
• Life table


  Provides data regarding the life history of an organism, divides the population into different age groups, and shows predicted life expectancy. Includes mortality rate and percentage of organisms within specific age intervals
• Survivorship curves


  The graphic representation of the data that a life table helps track. They show the number of individual organisms surviving at each stage in the organism's life cycle or each age

  
• 1. strategists


  Organisms that reproduce lots of offspring, be smaller, and focus less on maternal care. They are often also semelparous, which means that they reproduce only once throughout their lives
• 1. strategists


  Invest more in parental care and are slower to mature to their reproductive age. They often have more than one reproductive event throughout their lifetimes, making them iteroparous