density-dependent

Examples of density-dependent in the following topics:

• Density-Dependent and Density-Independent Population Regulation

  • Population regulation is a density-dependent process, meaning that population growth rates are regulated by the density of a population.
  • In population ecology, density-dependent processes occur when population growth rates are regulated by the density of a population.
  • An example of density-dependent regulation is shown with results from a study focusing on the giant intestinal roundworm (Ascaris lumbricoides), a parasite of humans and other mammals.
  • The actual cause of the density-dependence of fecundity in this organism is still unclear and awaiting further investigation.
  • In real-life situations, population regulation is very complicated and density-dependent and independent factors can interact.

• Overcoming Density-Dependent Regulation

  • Humans have exceeded density-dependent limits on population by enacting various environmental changes to accommodate our needs for hygiene, shelter, and food.
  • This capability is an underlying reason for human population growth as humans are able to overcome density-dependent limits on population growth, in contrast with all other organisms.
  • Describe ways in which humans overcome density-dependent regulation of population size

• Theories of Life History

  • The first variable is K (the carrying capacity of a population; density dependent), and the second variable is r (the intrinsic rate of natural increase in population size, density independent).
  • In some years, oaks may produce an exceptionally large number of acorns; these years may be on a two- or three-year cycle depending on the species of oak (r-selection).

• Hydrogen Bonding and Van der Waals Forces

  • Van der Waals attractions can occur between any two or more molecules and are dependent on slight fluctuations of the electron densities, which are not always symmetrical around an atom.

• Species Distribution

  • Density and size are useful measures for characterizing populations.
  • Patterns are often characteristic of a particular species; they depend on local environmental conditions and the species' growth characteristics (as for plants) or behavior (as for animals).
  • In this way, the dispersion pattern of the individuals within a population provides more information about how they interact with each other and their environment than does a simple density measurement.
  • Just as lower density species might have more difficulty finding a mate, solitary species with a random distribution might have a similar difficulty when compared to social species clumped together in groups.

• Diffusion

  • Molecules move constantly in a random manner at a rate that depends on their mass, their environment, and the amount of thermal energy they possess, which in turn is a function of temperature.
  • Solvent density: As the density of a solvent increases, the rate of diffusion decreases.
  • Because cells primarily use diffusion to move materials within the cytoplasm, any increase in the cytoplasm's density will inhibit the movement of the materials.
  • The rate of diffusion in this instance is almost totally dependent on pressure.

• Water’s Heat of Vaporization

  • (b) If the container is sealed, evaporation will continue until there is enough vapor density for the condensation rate to equal the evaporation rate.
  • This vapor density and the partial pressure it creates are the saturation values.
  • They depend only on the vapor pressure of water.

• Population Size and Density

  • Its density is the number of individuals within a given area or volume.
  • Individuals in a low-density population are thinly dispersed; hence, they may have more difficulty finding a mate compared to individuals in a higher-density population.
  • On the other hand, high-density populations often result in increased competition for food.
  • Many factors influence density, but, as a rule-of-thumb, smaller organisms have higher population densities than do larger organisms .
  • Scientist uses a quadrat to measure plant population size and density

• Organismal Ecology and Population Ecology

  • This preferential adaptation means that the Karner blue butterfly is highly dependent on the presence of wild lupine plants for its continued survival .
  • However, the distribution and density of this species is highly influenced by the distribution and abundance of wild lupine.

• Endocytosis

  • If uptake of a compound is dependent on receptor-mediated endocytosis and the process is ineffective, the material will not be removed from the tissue fluids or blood.
  • For example, the form of cholesterol termed low-density lipoprotein or LDL (also referred to as "bad" cholesterol) is removed from the blood by receptor-mediated endocytosis.