Scarlet Encina BSC 2011 EXAM 4 Lecture 26 Introduction to Ecology Reading Chapter 52 and biospheres organisms interact organisms Climate species nutrients Ecology is studied at the levels of individuals populations communities ecosystems landscapes Population group of individuals of the same species living in an area Community group of populations of different species in an area Ecosystem the community of organisms in an area and the physical factors with which those Understand that ecology is the study of factors affecting the distribution and abundance of Biotic factors living all the organisms that are part of the individual s environment o Negative influences Predation parasitism or competition Limit the distribution of Abiotic factors nonliving all the chemical and physical ex temperature light water and Understand that global climate is determined by the pattern of solar radiation striking the surface and local features such as mountains and bodies of water Solar radiation varies seasonally due to the rotation of the earth around the sun Tropics middle region of the earth that receives the most direct sunlight Surface heating drives air circulation o Intense solar radiation near the equator initiates a global pattern of air circulation and precipitation air from the tropic rises flows through the poles and returns to the equator tropics o Warm air over land rises air cools at high elevation cooler air sinks over water then this air moves inland replacing the warm air o Large bodies of water moderate effects on climate Mountains create rain shadows o When warm moist air approaches a mountain the air rises and cools releasing moisture on the windward side of the peak 1 Scarlet Encina o On the leeward side cooler dry air descends absorbing moisture and producing a rain shadow with little precipitation A desert is often present Biome major terrestrial or aquatic life zones characterized by vegetation type in terrestrial biomes or the physical environment in aquatic biomes Aquatic habitats are determined by the proximity to shore light bottom vs open water nutrients Benthic zone at the bottom of aquatic biomes Photic upper zone where there is sufficient light for photosynthesis Aphotic lower zone where little light penetrates o Wetland a habitat that is flooded by waters at least some of the time and supports plants adapted to water saturated soil o River has a current o Oceanic pelagic zone a vast realm of open blue water constantly mixed by wind o Estuary Coral Reefs are formed largely from the calcium carbonate skeletons of driven oceanic currents corals Terrestrial habitats are determined by temperature and moisture precipitation Tropical Forest high air temperatures year round moisture tropical rain forest constant tropical dry forests seasonal some dry months Desert biome with low precipitation Less than 30 cm per year Low vegetation Temperate Broadleaf Forest found mainly at the midlatitudes in the Northern Hemisphere hot in summer cold in winter has distinct vertical layers of vegetation Lecture 27 Populations and Life History Reading 53 1 and 53 2 Mark recapture m of individuals originally marked 180 n of individuals in second sample 44 x of individuals in both samples 7 Solving for population size N mn x x n m N 7 44 180 N N 180 44 7 1 131 4 Size and density Understand that populations can be described by size density dispersal and survivorship o Increases by birth and immigration influx of new individuals from other areas 2 Scarlet Encina of a population Patterns of dispersal o Decreases by death mortality and emigration the movement of individuals out o Clumped individuals are aggregated in patches where resources are high Common in plants and fungi clumped where soil conditions and other environmental factors favor germination and growth o Uniform evenly spaced results form direct interactions b w individuals in a population Individuals are competing for resources or physical space Ex penguins nesting to defend their eggs and physical space from other penguins territoriality o Random unpredictable spacing the position of each individual is independent of other individuals No strong attractions or repulsions exist or environmental factors are homogenous across the area Ex dandelions grow from windblown seeds that land at random and later germinate Not too common in nature there is more of a tendency to clump Survivorship Survivorship curves a plot of the proportion or numbers in a group still alive at each age Y number of surviors X age Type I flat at the start reflecting low death rates during early middle life and then drops steeply as death rates increase among older age groups mammals humans Type II intermediate constant death rate throughout the organisms life span squirrel rodents Type III drops sharply at the start reflecting very high death rates for the young but flattens out as death rates decline for those few individuals that survive the early period die off Organisms that produce a lot of offspring but little no care Fishes most marine invertebrates oyster Understand that different organisms have differing rates of survival and reproduction 3 Scarlet Encina Forces that influence population size birth death immigration emigration Reproduction effects on mortality o Semelparity big bang reproduction one shot to reproduce MANY offspring and then die Ex Agave plant stores nutrients during lifetime in desert until it has o Iteroparity repeated reproduction repeated or even annual reproduction of few enough to reproduce and then dies offspring at a time Ex lizards o Semelparity VS Iteroparity Depends on the survival rate of the offspring and the likelihood that the adult will survive to reproduce again Fecundity biological ability to bear children death Senescence Biological aging the process of aging resulting in deterioration and Understand that trade offs between different aspects of life history have been important in their evolution Cost to reproduction o A parent s survival might decrease by caring for young Ex Kestrel birds Tradeoffs b w offspring size and number o Plants animals whose young are subject to high mortality rates often produce large numbers of relatively small offspring Also true for animals that suffer high predation rates ex mice sardines Understand that lifespan is subject to natural selection Depend on when reproduction begins how often the organism reproduces and how many offspring are produced during each reproductive episode o
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