population dynamics miller 11th edition chapter 10

Population Dynamics Chapters 8 and 9, Miller 15th Edition,AP Environmental ScienceLCHSDr. E,Population Dynamics Outline,Characteristics of a PopulationPopulation Dynamics and Carrying CapacityReproductive StrategiesConservation BiologyHuman ImpactsWorking with Nature,Characteristics of a Population,Population - individuals inhabiting the same area at the same timePopulation Dynamics: Population change due toPopulation Size - number of individualsPopulation Density - population size in a certain space at a given timePopulation Dispersion - spatial pattern in habitatAge Structure - proportion of individuals in each age group in population,Population Size,NatalityNumber of individuals added through reproductionCrude Birth Rate - Births per 1000Total Fertility Rate Average number of children born alive per woman in her lifetimeMortalityNumber of individuals removed through deathCrude Death Rate Deaths per 1000,Population Density,Population Density (or ecological population density) is the amount of individuals in a population per unit habitat areaSome species exist in high densities - MiceSome species exist in low densities - Mountain lionsDensity depends uponsocial/population structuremating relationshipstime of year,Population Dispersion,Population dispersion is the spatial pattern of distributionThere are three main classificationsClumped: individuals are lumped into groups ex. Flocking birds or herbivore herds due to resources that are clumped or social interactions most common,/galleryphots/,Population Dispersion,Uniform: Individuals are regularly spaced in the environment - ex. Creosote bush due to antagonism between individuals, or do to regular spacing of resources rare because resources are rarely evenly spaced,/bloomingplants/creosotebush2.html,Age Structure,The age structure of a population is usually shown graphicallyThe population is usually divided up into prereproductives, reproductives and postreproductivesThe age structure of a population dictates whether is will grow, shrink, or stay the same size,Age Structure Diagrams,Positive Growth Zero Growth Negative Growth (ZPG)Pyramid Shape Vertical Edges Inverted Pyramid,Population Dynamics Outline,Characteristics of a PopulationPopulation Dynamics and Carrying CapacityReproductive StrategiesConservation BiologyHuman ImpactsWorking with Nature,Biotic Potentialfactors allow a population to increase under ideal conditions, potentially leading to exponential growthEnvironmental Resistance affect the young more than the elderly in a population, thereby affecting recruitment (survival to reproductive age),Biotic Potential,Ability of populations of a given species to increase in sizeAbiotic Contributing Factors:Favorable lightFavorable TemperaturesFavorable chemical environment - nutrientsBiotic Contributing Factors:Reproductive rateGeneralized nicheAbility to migrate or disperseAdequate defense mechanismsAbility to cope with adverse conditions,Environmental Resistance,Ability of populations of a given species to increase in sizeAbiotic Contributing Factors:Unfavorable lightUnfavorable TemperaturesUnfavorable chemical environment - nutrientsBiotic Contributing Factors:Low reproductive rateSpecialized nicheInability to migrate or disperseInadequate defense mechanismsInability to cope with adverse conditions,Population Growth,Population growth depends upon birth ratesdeath ratesimmigration rates (into area)emigration rates (exit area)Pop = Pop0 + (b + i) - (d + e)ZPG (b + i) = (d + e),Population Growth,Populations show two types of growthExponential J-shaped curveGrowth is independent of population densityLogistic S-shaped curveGrowth is not independent of population density,Exponential Growth,As early as Darwin, scientists have realized that populations have the ability to grow exponentiallyAll populations have this ability, although not all populations realized this type of growthDarwin pondered the question of exponential growth. He knew that all species had the potential to grow exponentiallyHe used elephants as an example because elephants are one of the slowest breeders on the planet,Exponential Growth,One female will produce 6 young over her 100 year life span. In a population, this amounts to a growth rate of 2%Darwin wondered, how many elephants could result from one male and one female in 750 years?19,000,000 elephants!,Exponential Growth Graph,Population Dynamics and Carrying Capacity,Basic Concept: Over a long period of time, populations of species in an ecosystem are usually in a state of equilibrium (balance between births and deaths)There is a dynamic balance between biotic potential and environmental resistance,Carrying Capacity (K),Exponential curve is not realistic due to carrying capacity of areaCarrying capacity is maximum number of individuals a habitat can support over a given period of time due to environmental resistance (sustainability),Logistic Growth,Because of Environmental Resistance, population growth decreases as density reaches carrying capacityGraph of individuals vs. time yields a sigmoid or S-curved growth curveReproductive time lag causes population overshootPopulation will not be steady curve due to resources (prey) and predators,Population Dynamics Outline,Characteristics of a PopulationPopulation Dynamics and Carrying CapacityReproductive StrategiesConservation BiologyHuman ImpactsWorking with Nature,Reproductive Strategies,Goal of every species is to produce as many offspring as possibleEach individual has a limited amount of energy to put towards life and reproductionThis leads to a trade-off of long life or high reproductive rateNatural Selection has lead to two strategies for species: r - strategists and K - strategists,r - Strategists,Spend most of their time in exponential growthMaximize reproductive lifeMinimum life,K,R Strategists,Many small offspringLittle or no parental care and protection of offspringEarly reproductive ageMost offspring die before reaching reproductive ageSmall adultsAdapted to unstable climate and environmental conditionsHigh population growth rate (r)Population size fluctuates wildly above and below carrying capacity (K)Generalist nicheLow ability to competeEarly successional species,K - Strategists,Maintain population at carrying capacity (K)Maximize lifespan,K,K- Strategist,Fewer, larger offspringHigh parental care and protection of offspringLater reproductive ageMost offspring survive to reproductive ageLarger adultsAdapted to stable climate and environmental conditionsLower population growth rate (r)Population size fairly stable and usually close to carrying capacity (K)Specialist nicheHigh ability to competeLate successional species,Survivorship Curves,Late Loss: K-strategists that produce few young and care for them until they reach reproductive age thus reducing juvenile mortalityConstant Loss: typically intermediate reproductive strategies with fairly constant mortality throughout all age classesEarly Loss: r-strategists with many offspring, high infant mortality and high survivorship once a certain size and age,Population Dynamics Outline,Characteristics of a PopulationPopulation Dynamics and Carrying CapacityReproductive StrategiesConservation BiologyHuman ImpactsWorking with Nature,Conservation Biology,Careful and sensible use of natural resources by humansOriginated in 1970s to deal with problems in maintaining earths biodiversityDedicated to protecting ecosystems and to finding practical ways to prevent premature extinctions of species,Conservation Biology,Three PrinciplesBiodiversity and ecological integrity are useful and necessary to all life on earth and should not be reduced by human actionsHumans should not cause or hasten the premature extinction of populations and species or disrupt vital ecological processesBest way to preserve earths biodiversity and ecological integrity is to protect intact ecosystems that provide sufficient habitat,Habitat Fragmentation,Process by which human activity breaks natural ecosystems into smaller and smaller pieces of landGreatest impact on populations of species that require large areas of continuous habitatAlso called habitat islands,1949 1964Habitat fragmentation in northern Alberta 1982 1991,Population Dynamics Outline,Characteristics of a PopulationPopulation Dynamics and Carrying CapacityReproductive StrategiesConservation BiologyHuman ImpactsWorking with Nature,Human Impacts,Fragmentation and degrading habitatSimplifying natural ecosystemsStrengthening some populations of pest species and disease-causing bacteria by overuse of pesticidesElimination of some predators,Human Impacts,Deliberately or accidentally introducing new speciesOverharvesting potentially renewable resourcesInterfering with the normal chemical cycling and energy flows in ecosystem,Population Dynamics Outline,Characteristics of a PopulationPopulation Dynamics and Carrying CapacityReproductive StrategiesConservation BiologyHuman ImpactsWorking with Nature,Working with Nature,Learn six features of living systems