Characteristics of Populations

• Population size (N) refers to the number of individuals of the same species living within a specific geographical location.
• Population density (D P) refers to the number of individuals per unit of volume or area.
• A transect is a long, relatively narrow rectangular area or line used for sampling a population.
• Type I populations have few offspring (low fecundity), high level of parental care.
• Type III populations have large number of offspring (high fecundity), no parental care.
• Type II populations have a consistent risk of mortality throughout the individual’s lifetime.
• Type III populations have a high rate of juvenile mortality and most individuals die before they become sexually mature or before they actually hatch.
• Populations seem to follow one of three patterns of survivorship: Type I with high rate of juvenile survival and individuals that live to sexual maturity, Type II with a consistent risk of mortality throughout the individual’s lifetime, and Type III where most individuals die as juveniles or before they become sexually mature.
• A quadrat is an area of specific size used for sampling a population. Used to sample immobile organisms or organisms that move very little.
• Transects are long and rectangular areas used for sampling larger and moving organisms.
• Mark-recapture is a method in which animals are captured, marked with a tag, collar, or band, released, then recaptured at a later time to determine an estimate of population size.
• Population distribution patterns include uniform, random, and clumped distributions.
• A clumped distribution takes place where resources are unevenly distributed, often resulting in positive interactions among individuals in a group.
• Life history is the survivorship and reproductive patterns shown by individuals in a population, serving as a quantitative measure of the vital statistics that determine a population size.
• A random distribution takes place where resources are plentiful and uniformly distributed across an area, eliminating the need for individuals to defend their share.
• A uniform distribution often takes place due to competition between individuals, where resources are evenly distributed but scarce.
• Distribution patterns can also be categorized as resource distribution, resource abundance, and interactions between members of a population.
• Life history includes measures such as sexual maturity, how often an individual reproduces, how many offspring an individual has at a time, and lifespan.
• There are two main measures in life history: fecundity, which is the average number of offspring produced by a female member of a population over her lifetime, and survivorship, which is the number or percentage of organisms that typically live to a given age in a given population.
• Population size is calculated by estimating the population size based on the distribution patterns.
• A cohort refers to a large group of individuals all born at the same time.
• Dp (population density) = N (population) /a (total area)
• Est. pop size = Dp x total study area
• Death rate = number of deaths per year/1000 people
• Birth rate = number of live births per year/1000 people
• N = (number originally marked) x (total individuals in recapture) / (marked individuals in recapture)