exam 2

• N- Population - total number of all the members of a single species living in a specific area at the same time.
• r-rate- rate of growth; the number of individuals which can be produced per unit of time under ideal conditions (with no limits to the populations growth)
• t-time- unit off time upon which the rate is based
• exponential growth - growth at a constant rate of increase per unit time (geometric); has not limit
• carrying capacity - maximum population size that an environment can support without degradation or collapse
• logistic growth - growth that slows down as resources become limited
• density dependent factors - factors that affect population density, such as food availability, predators, disease, competition, etc.
• logistic growth - exponential growth with a carrying capacity, when r=K, K is the carrying capacity
• density independent factor - factors that are unrelated to density but still influence population growth ex- droughts, fire, habitat destruction
• R- Selected Species- High Reproductive rates, give little or no care to offspring. High mortality rates.
• K-Selected Species - conservative reproduction rates, longer generation times, late sexual maturity, fewer young. Live longer, have few natural predators.
• Four factors that contribute to r(rate of growth) - birth + immigration - deaths+emigration
• intrinsic- the ability to perform a skill without any external assistance or instruction, the ability to perform a skill naturally. *operating within individual organisms or between organisms in the same species.
• Extrinsic - the external factors that influence the behavior of an individual. *imposed from outside the population
• biotic - living organisms
• abiotic - non living organisms
• Type I- most individuals die late in life; elephants, bears
• Type II- Individuals die at a uniform rate ; birds, mice
• Type III- most individuals die at a young age - fish, butterflies,
• Intraspecific - within a species
• intraspecific interactions - individuals of a species compete for same resources. To limit competiton and control access of resources, establishing separate territories is common.
• stress and crowding are density dependent control factors
• factors of populations - reproduction, growth, mortality, population size
• The Equilibrium Theory of Island Biogeography - Diversity(the number of species) in isolated islands depends on rates of colonization and extinction
• Genetic Drift - the gradual changes in gene frequencies due to random events
• Founder Effect - the reduction of genetic diversity in a small population
• Bottleneck effect - when a large population is reduced by some catastrophic event (fire, flood), resulting in rapid change in allele frequency
• Mutation - spontaneous alterations in DNA sequence that may be beneficial or detrimental
• in small of isolated populations, the pool of traits is smaller and genetic drift can occur because unusual traits in a few individuals can become dominant in a small population.
• Human population growth causes environmental degradation(Thomas Malthus)

  Human population growth results from poverty and resource depletion( Karl Marx)
• Technology can boost carrying capacity as we make progress in agriculture, engineering, commerce and medicine. These achieveme make it possible to support many more people per unit area.
• IPAT-

  I=Pat

  I=environmental impact

  P=population

  A= affluence

  T=technology
• demography- encompasses vital statistics about people such as births, deaths, distribution, and population size.
• Crude Brith Rate- number of births in a year per thousand.
• Total Fertility rate- average number of children born by women during their reproductive years
• Crude Death Rate- number of deaths per thousand persons in a given year
• Replacement Fertility Rate- occurs when birth rates just compensate for deaths.
• Development, life expectancy, age distribution, and social factors can affect population growth.
• Stage two has declining death rates but still high fertility.
• Stage one is high fertility and mortality with low economic development.