Vocabulary:

• Population: Members of a single species that inhabit a defined geographical area. This area can vary greatly by the species

• Population size: The metric that measures the amount of individuals within a population

• Population density: The metric that measures how many individuals of a population live in a given unit of area

• Absolute abundance: The precise number of individuals in a given area, very specific and exact

• Relative abundance: The number of individuals of a given species compared to the total number of individuals of all of the species in a given area

• Demography: The study of characteristics for a population, including size, density, age structure, fecundity, mortality, and sex ratios

• Age structure: Consists of the population of individuals of different age classes within a population, which is a reflection of several aspects of population dynamics, including the history of survival, reproduction, and the potential for future growth

• Fecundity: The potential ability of an organism to produce eggs or young, the rate of production of young by a female

• Niche space: Environmental factors that influence survival, growth, and reproduction of populations, not individuals. This is all of the available habitat and resources available where an organism lives, classified at the population level

• Fundamental niche: The environmental conditions under which a population or species lives in, in the absence of competition of other species. What would the population prefer

• Realized niche: The actual resources and environment that a species inhabits and utilizes, due to competition with other species. This may vary from population to population of the same species

• Population partitioning: The phenomenon of species choosing their realized niches, suitable habitats are often patchy

• Dispersal limitation: When various factors limit the range that a species can cover, and reach suitable habitats, due to unsuitable habitats being in the way

• Population dispersion: The scatter of individual organism within the population, can be a measure of density as compared to overall area

  • Random: Scattered

  • Regular: Typical distribution, no unevenness

  • Clumped: If they are social organism and live in smaller groups

• Density-independent effect: Something that controls a population’s size, determined by factors that operate regardless of population size, like weather or physical disruption. These limit energy uptake, which in turn determines range limits

• Density-dependent effect: Something that controls a population’s size, determined by factors that are influenced by a populations size. This is more effective when the population and it’s density are large

• Combining factors: Limit a population, influence both density and range. These include specialized/generalist habitat and food requirements, how tolerant a population is to a habitat

• Carrying capacity (K): The limit of the number of individuals in a population, determined by the number that the environment can support, no net increase of decrease, modeled by logistic functions. As a population approaches this, there is more immigration out, more competition for resources, and the accumulation of toxic waste. The risk of disease increased

• Population size: How large a population is, a function of birth and death, immigration, and emigration

• Life table: Ways to break down a population, display sex, age, mortality rates, causes of death, and other factors to estimate a population size

  • Cohort life table: A subset of the population born during the same time, “birth to death table”, typically created under laboratory conditions

  • Static life table: A snapshot in time, doesn’t range over time but takes a moment and expands data, based on population age distribution, time-specific

• Multiplicative growth: How a population grows, due to more individuals being able to produce even more offspring and an increasing rate

• Continuous time approach: Models how populations change constantly, population growth rate per unit of time

• Population dynamics: Processes that underlie the distributions and abundance of organisms. Modeled by Nt=(Nt-1)+B+I-D-E, Nt is individuals in a population at some point in time, Nt-1 is individuals at a previous time, B is birth, I is immigrants, D is deaths, and E is emigrations

• Discrete growth: Demographic events occur in discrete units of time, without overlapping of generations. i.e. there are breeding seasons. Modeled by Nt=N0xR0^t, with Nt being population size at time t, N0 being initial population size, and R0 being net reproductive rate. This model assumes that r is not related to N (per capita birth rate and population size) along with birth and death rates being unrelated to population size (no density dependent effects)

• Continuous growth: Demographic events occur continuously, not depending on season/climate/food etc. Modeled by dN/dt=rN, with dN/dt being change in population size, r being intrinsic rate of increase per capita rate of increase, and N being population size. This equation results in Nt=N0e^rt, with N0 being initial population size, Nt being population size at time t, e being the base of the natural log, r being b-d, b being instantaneous per capita birth rate, and d being instantaneous per capita death rate

• Exponential growth: A result of multiplicative growth, the population multiplies and grows by a specific rate each time interval, a j-shaped growth curve. More individuals means more growth, maximum rate of increase per individual under ideal conditions, varies from species to species. Rarely reached in nature, only observed in humans.

• Warmer springs: Cause a mismatch of fecundity and food availability

• Logistic growth: “real” population growth, grows until carrying capacity and makes an s-shaped curve. Modeled by dN/dt=rN((K-N)/K), with dN/dt being change in population size, N bein the number of individuals in a population, r being the intrinsic rate of increase per capity growth, and K being carrying capacity. Now, growth rate is proportional to size with relation to carrying capacity

• Survivorship curves: Describe how many organisms survive to what age for a population

  • Type I: High survival of young, with the older ones dying off, high parental care

  • Type II: Constant rates of survival, old die as frequently as young

  • Type III: High survival of old organisms, but low survival of young, like those with low parental care