For 232 1st Edition Lecture 10Outline of Last Lecture I. DecomposersOutline of Current Lecture: I. PopulationII. DensityIII. Genets and RametsIV. MetapopulationsV. Spatial DispersionVI. Temporal DispersionVII. Dispersal MovementVIII. Age structure and Sex ratiosIX. Population growth and Carrying Capacity X. Density DependenceXI. Density IndependenceXII. Natality and mortalityXIII. Survivorship CurvesCurrent LectureI. Population:a. Is a group of individuals of the same species occupying a given space at a given timei. Boundaries of space and time depend on the situationb. Populations have properties that are not associated with individuals:i. Density *an individual has a density of oneii. Age structureiii. Sex rationiv. Birth and death ratesv. Immigration, emigration and migration ( I in immigration is for coming In, E in emigration if Exiting)vi. Growth ratesc. Multiple populations occupying the same place and time = communityII. Density:a. Population size in relation to area is densityb. Crude density: number of individuals per unit total areaThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.i. But populations cannot occupy all space, because not all space is equally good habitatc. Ecological density: number of individuals per unit suitable habitat (or living space)i. It’s difficult to estimate ecological density in most casesIII. Genets and Ramets:a. Some organisms are clonal, including trees like aspen (Populus spp.)b. Individual plants produced by sexual reproduction = genetc. Plants produced by vegetative (asexual) propagation = rametsd. Ramets arising from the same genet make up a clonee. Ramets often become separated from the ‘parent” plant but remain geneticallt identicalf. A grove of aspen clone in Colorado is thought to be the oldest organism on Earth (10,000 years)IV. Metapopulations:a. A group of populations connected in some way is a metapopultionb. Sub-populations are connected by movement of individuals.c. Conditions and resources needed for populations to thrice are not uniformly distributed across an area.i. This heterogeneity often meanspopulations exist in favorable places.ii. Populations are genetic units, all genetic information in a population is the gene pool. Sub-populations in a metapopulation are connected by a gene flow.V. Spatial Dispersion:a. Populations are distributed or dispersed in space.b. Random distributions are rare in naturei. Requires a uniform environment and no interations within populationc. Uniform distributions are more commoni. Territorial species in uniform environments, resulting from competitionii. Plantation forestsd. Clumped distributions are most commoni. Represents population responses to ‘patchy’ of heterogeneous resource availability, environmental conditioned, habitat suitability, species interactions, etc.ii. Often result in metapopulations connected via gene flowVI. Temporal Dispersiona. Individuals and populations are distributed temporallyb. Circadian rhythms dictate patterns of daily, seasonal and yearly behaviorc. Diurnal= active during dayd. Nocturnal= active during nighte. Seasonal cycles influence populations:i. Deciduous treesii. Migratory birdsiii. Insect pollinatorsVII. Dispersal Movement:a. Individuals in a population may move from one sub-population to anotherb. Emigration- leaving original sub-population for another (moving away)c. Immigration- arriving in a different sub-population (moving in)d. Migration- a round-trip movement pattern, often cyclical (every year)i. Movement can be active or passivee. Methods of dispersal:i. Sessile species use many different passive strategies to disperse their seeds or propagules1. Wind, gravity and water2. Birds, fishes and mammals (via fruit that is eaten or as a ‘hitchhiker’)ii. Mobile species use active strategies for getting one place to anotheriii. Capable of traveling on land (including fish) and sea (including mammals)iv. Natal dispersal- young seeking territory or better habitatv. Breeding dispersal- adults seeking better reproductive sites VIII. Age Structure and Sex ratiosa. Age structure is the distribution of ages represented in populationb. Provides demographic information and related to several population processesc. Ages can be in days, months, years, decades, centuries, etcd. Age structure can also be estimated with life-history stages or size classese. Stable age distribution= rations among age classes are equal (or nearly so)f. Sex ratio= males/ females a birth and at any given ag in the populationIX. Population growth and Carrying Capacity a. Populations grow in three generalized ways:i. The rate of growth ® is determined by relative rates of fecundity (births) and mortality (deaths) and is almost always dynamic (changing)ii. Most populations in natural environments experience exponential or logistic growthiii. Carrying Capacity (K) is the maximum population size that can be supported by a given environmentiv. K may be determined by density dependent factors, like competition, and/or density independent factors, such as limiting resources or disturbances regimesv. K is theoretical… very difficult to estimate for a single population in a real environmentX. Density Dependence:a. Population density affect population dynamics via one or more parameters:i. Fecundityii. Mortalityiii. Survivorshipiv. Healthb. Negative density dependence: increasing population density has negative effect on growth rates: ↓fecundity↑mortalityc. Density dependent inhibition examples:i. Competitionii. Crowding in growing spaceiii. Over-browsingiv. Some diseasesXI. Density Independence:a. Population dynamics and parameters that are not related to population densityb. Typically thought of as ‘external’ factors to population itselfc. Limiting factors to growth (law of minimum):i. Resourcesii. Environmental tolerancesd. Large-scale or serve disturbances can cause irregular fluctuations in populations:i. Storms (wind, rain, ice)ii. Earthquakes and landslidesiii. Fireiv. Climate changev. Insects, parasites, some diseasesXII. Natality and mortality:a. Birth rate (natality): is the most important factor for population growthb. Physiological natality: is the maximum number of possible births for an individualunder ideal conditionsc. Realized natality: is the amount of successful breeding that actually occurs in the natural environmentd. Fitness: