POPULATION DYNAMICS

 

Population Ecology

Exponential growth and doubling time:

  • Exponential growth: growth at a constant RATE of increase per unit of time. The sequence follows a _________ rate of increase which is multiplied together (ex. 2,_,_,__)

    This results in a J-curve of population growth which is very, very ______!

    Animals that grow in a J-curve often have a ___-selection reproductive strategy. They are low on the trophic level, grow quickly and mature _____, produce lots of offspring and are ______-beat parents. ex. insects, rodents, marine invertebrates, parasites and annual plants.

    Riddle: If a water lily grows at an exponential rate and covers a pond in 30 days, on what day was the pond 1/2 covered?

  • ____________ growth: increases at a constant AMOUNT per time which is _______ together. (ex. 1, _, _, _, _)

    The population growth is not so ________!

  • Doubling time: Amount of time it takes for the population to ________.
  • Rule of _____= 70 / annual ___ growth

Biotic Potential and Carrying Capacity

  • Biotic ___________- the maximum growth rate of a population of organisms.

    What is the biotic potential for the human female?

  • Carrying capactiy- the _________ number of individuals of a population that can be sustained __________ in an ecosystem.

Population Oscillations

  • Population exceeds carrying capacity or limiting factors come into effect, death rates surpass birth rates = population _____ or __________
  • ____________- the extent to which a population _________ the carrying capacity      
  • Irruptive/Malthusian growth-  the pattern of  population __________ followed by a population ________

 

Growth to a Stable Population

  • Growth rates regulated by internal and external factors limit population growth. This pattern of logistic growth is called a ___-curve.

 

 

  • The factors that reduce population growth rates are called environmental resistance. ex. space, food, water.
  • Organisms in the ___-selection reproductive strategy often exhibit logistic growth. They grow and mature more ________, have _______ offspring, and care for their young. There is a high expectation that the young will survive. ex. wolves, elephants, whales and primates.
    • Why aren't humans showing a s-curve population growth pattern then????

     

Factors that Increase/Decrease Populations

Natality, Fecundity and Fertility

  • Natality: production of new individuals. It is the main source of adding to populations, sensitive to environmental conditions (nutritional levels, climate, soil and water conditions, social interaction between species).
  • Fecundity: physical ability to __________
  • Fertility: measure of the actual number of _________ produced.
  • _______________: Seeds, spores, and small animals may be __________ into new ecosystems by wind, water (major source of organisms to islands), carried inside other animals, walking, swimming, flying,

Mortality and Survivorship

  • Mortality: _______ rate. The death rate is found by dividing the number of organisms that ____ in a certain time period by the number _______ at the beginning of the period.
  • Survivorship: the __________ of a certain organism that lives to be a certain age.
  • Life Expectancy: probable number of ________ of survival of an individual of a given age.
  • Life Span: __________ period of life reached by a given type of organism.
  • Emigration: the movement of members _____ of a population.

Survivorship Curves gives us the predicted life expectancy at each age interval.

  • Type I or a: Mortality mostly occurs in old age. ex. _________ in the first world.
  • Type II or b: Mortality is _____ dependent on age. ex. Hyrdas, squirrels and ___ _____ randomly die throughout their lives.
  • Type III or d: Species that mostly die when they are young would follow this curve. ex. Most marine organisms have a low survivorship- they are cast out into the waters, but once they survive that trauma they are likly to live out their ____ age. Other examples are trees and other plants that spread a lot of seeds.
  • Type "c": Some surviviorship curves include a fourth opinion in which high mortality occurs in the very _____ AND _____. ex. White tailed deer.

 

Factors that Regulate Population Growth

 

Extrinsic: limiting factors are imposed from _________ the population

  • Biotic: caused by _______ organisms. Preditor/prey oscillation curves are common. They actually oscillate in synchrony of each other- but in a time lag.

    • Biotic factors are caused by limited food supply, predators, disease.

    •  

  • Abiotic: caused by ____-_______ components of the environment. ex. temperature, light, pH, water.

Intrinsic: limiting factors come from _______ the population: reproductive rate, adaptability, territoriality, the size of your car engine and tax returns...

 

Density dependent: effects are stronger or a higher percentage of the population is affected as the population density ________ (usually biotic factors like food shortages, droughts)

Density independent: the effect is the same or a _______ _________ of the population is affected regardless of the population density (usually abiotic factors like fire, climate conditions, volcano, earthquakes, severe storms)

Huffaker experiment primary document and Huffaker II

Making the models more realistic