Outline of Last LectureOutline of Current LecturePopulation EcologyAnalysis of DemographyLife HistoryHow populations growAge structureEcological footprintReviewBIO SCI 150 1st Edition Lecture 19 Outline of Last Lecture 1. Ecologya. Behaviori. Learning and Flexibility1. Nature vs. Nurture2. The Adaptive Consequences of Behavior3. Honest vs. Deceitful Communicationa. Hamilton’s Ruleb. Do animals favor their relatives?Outline of Current Lecture 1. Population Ecologya. Analysis of Demographyi. Life Historyb. How Populations Growi. Age Structurec. Ecological FootprintKey TermsPopulation: a group of individuals of the same species living in the same areaDemography: study of factors that influence the size and structure of populations through timeLife tables: summarize the probability that an individual will survive and reproducein any given year over the course of its lifetime.Survivorship curve: plots numbers of surviving individuals at each ageLife History: How an organism allocates resources to reproduction and survivalReproductive Strategies:- Semelparity: produce all offspring in single reproductive event, individuals reproduce once and die- Iteroparity: reproduce in successive years or breeding seasonsExponential growth: When r > 0, population increase is rapidAge Structure: Relative numbers of individuals in each defined age groupTotal fertility rate: average number of live births a woman has during her lifetimeEcological Foot Print:Total land area used for food, shelter, clothing, energy, travel, etcPopulation EcologyPopulation: a group of individuals of the same species living in the same area - How and why do populations change over time? - Populations change due to:o Immigrationo Birthso Deathso Emigrationo I + B = D + E- Demography - study of factors that influence the size and structure of populations through time- Quantifying population densityo Simple visual counto Sampling methods: extrapolate number captured to size of populationo Mark-recapture method- Age classes: different age groupso Increasing populations: many young o Decreasing populations: few youngAnalysis of DemographyLife tables: summarize the probability that an individual will survive and reproduce in any given year over the course of its lifetime.Survivorship curve – plots numbers of surviving individuals at each ageLife HistoryHow an organism allocates resources to reproduction and survival- Reproductive strategieso Semelparity – produce all offspring in single reproductive event, individuals reproduce once and dieo Iteroparity – reproduce in successive years or breeding seasons- To calculate future size of population, multiply number of individuals in the population by the net reproductive rateo For beaver example,  Nt+1 = NtR0- = 1,000 x 1.1- = 1,100o If R0>1, population growingo If R0<1, population decliningo If R0 = 1, population is at equilibriumHow populations grow- Life tables can provide information about how populations grow from generation to generation- Simpler models can give insight to shorter time periodso Exponential growth – resources not limiting, prodigious growtho Logistic growth – resources limiting, limits to growth- Exponential growtho When r > 0, population increase is rapido Characteristic J-shaped curveo Intrinsic rate of increase, rmax = r at maximumo Because population growth depends on the value of N as well as the value of r, the population increase is even greater as time passeso Reintroduction of a population to a habitat, growth of introduced exotic species, and global human populationo Exponential growth continues indefinitely and is density-independent Step 1: Determine the rate of increase (r) Step 2: plug in numbers into growth equation- Nt= N0er t Step 3: solve for t No population can continue to grow indefinitely. At high densities, growth becomes density-dependent. All populations eventually reach the carrying capacity of their habitat.What factors limit exponential growth?- Depletion of resources- Predation- Disease & Parasitism- StressDensity-dependent survival or reproductionLinear decreaseDensity-independent factorsFactors affecting population growth that are not related to densityAbiotic events: hurricanes, droughts, frostsAge structureRelative numbers of individuals in each defined age groupTotal fertility rate – average number of live births a woman has during her lifetime- Global TFR declined from 4.47 in 1970s to 2.59 in 2007- 2.3 needed for zero population growthEcological footprintTotal land area used for food, shelter, clothing, energy, travel, etc- Average footprint size is about 3 hectares (1ha=10,000 m2)We already exceed the earth’s carrying capacity- Human populations can exist at equilibrium densities in one of two wayso High birth and high death rates Before 1750, this was often the case, with high birth rates offset by deaths from wars, famines, and epidemicso Low birth and low death rates In Europe, beginning in the 18th century, better health and living conditions reduced the death rate Eventually, social changes such as increasing education for women and marriage at a later age reduced the birth rateReview- I + B = D + E- Exponential and logistic growth- Carrying capacity- Density-independent- Density-dependent factors- Demography – study of factors that influence size and structure of populations- Life History – schedule of reproduction and