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Population Ecology

  • population ecology: the study of intraspecific interactions

  • intraspecific interactions: organisms interacting with members of the same species in relation to environment

  • biotic and abiotic factors affect density, size and age structure of populations

  • density: the number of individuals per unit area/volume

  • dispersion: pattern of spacing among individuals in the population

  • How do scientists measure density?

    • counting individuals, nests, burrows, tracks, etc

    • quadrant sampling

      • ex: counting the number of oak trees in 100mx100m plots in Troy, then calculate average in the city

    • Mark-recapture: mark individuals from a sample of the population, release back into the population. once mixed, take new sample and record ratio or marked to unmarked

  • 3 types of dispersion: clumped, uniform, random

  • Demography: study of statistics of populations and changes over time

  • Life tables: age-specific summaries of the survival pattern of a population from birth to death

  • cohorts: individuals of the same age

  • data from life table is put into a survivorship curve

  • reproductive table: based on female cohorts producing offspring from birth to death

  • What cycles do many mammals have that reabsorbs endometrial lining when not pregnant? estrous cycle

  • What bone in the penis aids in copulation(mating) in most mammals(not humans)? baculum

  • Generation time: amount of time between birth of individual vs it’s offspring

  • small organisms - shorter generation times

    • ex: bacteria dividing asexually by binary fission every 20 minutes

  • large organisms - longer generation times

  • What factors limit colony size of bacteria? limited resources, toxic waste accumulation, predation, viruses(bacteriophages)

  • Viruses at minimum have : nucleic acid(DNA + RNA) and protein coat(capsid)

  • exponential population growth(r-selected) - populations that have access to abundant resources and reproduce without limits

  • logistic population growth(k-selected) - populations with limited resources that cause populations to reach a plateau

  • the plateau in logistic population growth is also called: carrying capacity(K)

  • semelparity - a single, large reproductive effort

  • iteroparity - repeated reproduction

  • life history - traits that affect an organism’s schedule of reproduction and survival

    1. start of reproduction

    2. how often reproduction occurs

    3. how many offspring per reproductive episode

  • r-selected - reproductive success in uncrowded environments

  • k-selected - life history traits sensitive to population density

  • Fewer offspring = longer lifespan of parents

  • more offspring = more energy invested in offspring

  • “principle of allocation” : more energy for on function = less energy for other function

  • reproductive diapause: allocation of energy from breeding to migration for survival

  • density-dependent factors: factors that affect populations as it becomes denser

  • density-independent factors: factors that affect population size regardless of the number of individuals

  • populations can fluctuate in density with regular boom-and-bust(periodic) cycles

    • cicadas emerge from the ground every 13-17 years depending on the species

  • age structure - number of individuals of each age in the population

  • ecological footprint - land and water required by each person, city, or nation to produce all resources consumed and absorb the waste

  • limiting factors that could lead to Earth reaching carrying capacity

    1. Food(Malnutrition/famine)

    2. sustainable space

    3. lack of resources(decline of non/renewable resources)

    4. inability to absorb waste

Population Ecology

  • population ecology: the study of intraspecific interactions

  • intraspecific interactions: organisms interacting with members of the same species in relation to environment

  • biotic and abiotic factors affect density, size and age structure of populations

  • density: the number of individuals per unit area/volume

  • dispersion: pattern of spacing among individuals in the population

  • How do scientists measure density?

    • counting individuals, nests, burrows, tracks, etc

    • quadrant sampling

      • ex: counting the number of oak trees in 100mx100m plots in Troy, then calculate average in the city

    • Mark-recapture: mark individuals from a sample of the population, release back into the population. once mixed, take new sample and record ratio or marked to unmarked

  • 3 types of dispersion: clumped, uniform, random

  • Demography: study of statistics of populations and changes over time

  • Life tables: age-specific summaries of the survival pattern of a population from birth to death

  • cohorts: individuals of the same age

  • data from life table is put into a survivorship curve

  • reproductive table: based on female cohorts producing offspring from birth to death

  • What cycles do many mammals have that reabsorbs endometrial lining when not pregnant? estrous cycle

  • What bone in the penis aids in copulation(mating) in most mammals(not humans)? baculum

  • Generation time: amount of time between birth of individual vs it’s offspring

  • small organisms - shorter generation times

    • ex: bacteria dividing asexually by binary fission every 20 minutes

  • large organisms - longer generation times

  • What factors limit colony size of bacteria? limited resources, toxic waste accumulation, predation, viruses(bacteriophages)

  • Viruses at minimum have : nucleic acid(DNA + RNA) and protein coat(capsid)

  • exponential population growth(r-selected) - populations that have access to abundant resources and reproduce without limits

  • logistic population growth(k-selected) - populations with limited resources that cause populations to reach a plateau

  • the plateau in logistic population growth is also called: carrying capacity(K)

  • semelparity - a single, large reproductive effort

  • iteroparity - repeated reproduction

  • life history - traits that affect an organism’s schedule of reproduction and survival

    1. start of reproduction

    2. how often reproduction occurs

    3. how many offspring per reproductive episode

  • r-selected - reproductive success in uncrowded environments

  • k-selected - life history traits sensitive to population density

  • Fewer offspring = longer lifespan of parents

  • more offspring = more energy invested in offspring

  • “principle of allocation” : more energy for on function = less energy for other function

  • reproductive diapause: allocation of energy from breeding to migration for survival

  • density-dependent factors: factors that affect populations as it becomes denser

  • density-independent factors: factors that affect population size regardless of the number of individuals

  • populations can fluctuate in density with regular boom-and-bust(periodic) cycles

    • cicadas emerge from the ground every 13-17 years depending on the species

  • age structure - number of individuals of each age in the population

  • ecological footprint - land and water required by each person, city, or nation to produce all resources consumed and absorb the waste

  • limiting factors that could lead to Earth reaching carrying capacity

    1. Food(Malnutrition/famine)

    2. sustainable space

    3. lack of resources(decline of non/renewable resources)

    4. inability to absorb waste

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