Bio notes week 14
Bio notes week 14 BIO 121 - M001
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BIO 121 - M001
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This 0 page Class Notes was uploaded by Andrea Scota on Saturday December 12, 2015. The Class Notes belongs to BIO 121 - M001 at Syracuse University taught by Staff in Fall 2015. Since its upload, it has received 24 views. For similar materials see General Biology I in Biology at Syracuse University.
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Date Created: 12/12/15
mentioned in class Bio Notes Week 14 TEXTBOOK CHAPTER 53 Population Ecology Biological processes in uence population density dispersion and demographics 531 0 Density of a population the number of individuals per unit area or volume 0 Re ects birth rates death rates immigration and emigration 0 Immigration in ux of new individuals from other areas 0 Emigration movement of individuals out of a population into other locations 0 Dispersion of a population the pattern of spacing among individuals within the boundaries of a population 0 Can be clumped uniform or random 0 In uenced by environmental and social factors like Territoriality the defense of a bounded physical space against encroachment by other individuals occurs in uniform dispersion 0 Demography the study of the vital statistics of populations and how they change over time o Populations increase from births and immigration 0 Populations decrease from deaths and emigration 0 Life tables survivorship curves and reproductive tables summarize speci c trends in demography 0 Life tables age speci c summaries of the survival pattern of a population I Oftentimes construct by following the life of a cohort a group of individuals of the same age from birth until all of the individuals are dead 0 Survivorship curves a plot of the proportion or numbers in a cohort still alive at each age 0 Reproductive table fertility schedule is an agespeci c summary of the reproductive rates in a population The experimental model describes population growth in an idealized unlimited environment 532 o If immigration and emigration are ignored a populations growth rate the pre capita rate of increase equals the birth rate minus the death rate Exponential growth equation dNdt rinstN represents a population s growth when resources are relatively abundant o rim is the instantaneous per capita rate of increase 0 N is the number of individuals in the population 0 Zero population growth ZPG occurs when the per capita birth and death rates are equal The logistic model describes how a population grows more slowly as it nears its carrying capacity 533 Exponential growth cannot be sustained for long in any population Carrying capacity K the maximum population size that a particular environment can sustain Population models are limited by this 0 According to the logistic growth equation dNdt rinstNKNK growth levels off as population size approaches the carrying capacity 0 The logistic growth model ts few real populations perfectly but it is useful for estimating possible growth Life history traits are products of natural selection 534 0 Life history traits evolutionary outcomes re ected in the development physiology and behavior of organisms Semelparous bigbang organisms reproduce only once and die 0 Iteroparous organisms produce offspring repeatedly Life history traits like brood size age at maturity and parental caregiving represent tradeoffs between con icting demands for time energy and nutrients Kselection density dependent selection 0 rselection densityindependent selection Many factors that regulate population growth are density dependent 535 Densitydependent population regulation death rates rise and birth rates fall with increasing density 0 Densitydependent changes in birth and death rates curb population increase through negative feedback and can eventually stabilize a population near its carrying capacity 0 Limiting factors include intraspeci c competition for limited food or space increased predation disease intrinsic physiological factors and buildup of toxic substances Densityindependent population regulation birth and death rates do not vary with density Population dynamics are in uenced by many factors and in turn affect other species Because changing environmental conditions periodically disrupt them all populations undergo regular boomandbust cycles that are in uenced by complex interactions between biotic and abiotic factors Metapopulation group of populations linked by immigration and emigration The human population is no longer growing exponentially but is still increasing rapidly 536 Since about 1650 the global human population has grown exponentially but within the past 50 years the rate of growth has fallen by half Demographic transition the movement of high birth and death rates towards low birth and death rates 0 Usually follows industrialization or improved living conditions Difference in age structure the relative number or individuals of each age in the population show that while some nations populations are growing rapidly those of other are stable or declining in size Infant mortality rates and life expectancy at birth vary widely in different countries Ecological footprint the aggregate land and water area needed to produce all the resources a person or group of people consume and to absorb all of their wastes It is one measure of how close we are to the carrying capacity of Earth which is still uncertain We are using many resources in an unsustinable manner KEY CONCEPTS A community consists of populations that live in the same place at the same time Community ecologists focus on questions concerning the number of species the relative abundance of each species interactions among species and resistance of community to environmental disturbances Ecologic Niche An organisms distinctive lifestyle and role in a community takes into consideration all abiotic and biotic aspects of organisms existence An organisms habitat where it lives O O O 0 one parameter used to describe its niche Types of Niches Organism could use more resources and have more in uence on their community than they actually do Fundamental niche organisms potential ecological niche Realized niche the niche organism actually occupies Competition Occurs when two or more individuals try to use the same essential resource food water shelter living space sunlight Intraspeci c competition among individuals within a population Interspeci c competition among individuals between species Competitive Exclusion Principle Two species cannot occupy the same nice in the same community for an inde nite period of time One is better than other What process do you think are responsible for effective dividing of resources in nature The nonrandom lter of natural selection Character Displacement Reduces competition among some species structural ecological behavioral characteristics diverge where ranges overlap Example bill sizes of Darwin s nches where medium ground nch and small ground nch live together bill depths are distinctive Where two species live separately bill depths are same intermediate size Solar Energy Of solar energy that reaches earth 30 immediately re ected away 70 absorbed by atmosphere and surface Absorbed solar energy reradiated into space as inferred heat radiation O O O O O Hydrologic cycle In ecosystems energy ow one way through the system and materials cycle and recycle Species Richness is often greatest in habitats with structural complexity a community that is not isolated distance effect of severely stressed A community where more energy is available species richness energy hypothesis communities without recent major disturbances ecotones transition zones between communities Community Stability studies suggest species richness may promote community stability quotRivet hypothesis Remember all of this goes back to ow of energy and cycling of materials Solar Energy Concentrated at equator diluted at poles due to Earth s spherical shape Tropics are hotter less variable in climate than temperature and polar areas Why are there seasons in Earth s temperate regions Tilt of the Earth s axis Heat energy Can be moved around by winds and ocean currents This can have a big effect on climate Atmospheric Circulation diagram Surface Ocean Currents Diagram Precipitation In uences latitude Elevation Topography Vegetation Distance from ocean large bodies of water Location on a continent or other landmass O O O O O O O O O O 0 Greatest where warm air passes over ocean Biome A large relatively distinct terrestrial region with characteristic climate soil plants and animals Biome Characteristics Chart KEY CONCEPT Climate particularly temperature and precipitation affects the distribution of Earth s major biomes Aquatic Ecosystems Important environmental factors salinity concentration of dissolved salts amount of dissolved oxygen availability of light levels of essential minerals water depth temperature pH presence or absence of waves and currents Declining Biological Diversity Human acidities reduce biological diversity habitat loss and habitat fragmentation pollution introduction of invasive species pest and predator control illegal commercial hunting commercial harvest
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