Scarlet Encina BSC 2011 EXAM 4 Lecture 26 Introduction to Ecology Reading Chapter 52 Ecology is studied at the levels of individuals populations communities ecosystems landscapes and biospheres 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 organisms interact Understand that ecology is the study of factors affecting the distribution and abundance of organisms Climate Biotic factors living all the organisms that are part of the individual s environment o Negative influences cid 224 Predation parasitism or competition Limit the distribution of species Abiotic factors nonliving all the chemical and physical ex temperature light water and nutrients 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 Surface heating drives air circulation Solar radiation varies seasonally due to the rotation of the earth around the sun Tropics cid 224 middle region of the earth that receives the most direct sunlight 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 1 Scarlet Encina o When warm moist air approaches a mountain the air rises and cools releasing moisture on the windward side of the peak 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 Aphotic lower zone where little light penetrates Photic upper zone where there is sufficient light for photosynthesis 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 driven oceanic currents o Estuary Coral Reefs are formed largely from the calcium carbonate skeletons of 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 cid 224 N mn x 2 Scarlet Encina x n m N 7 44 180 N N 180 44 7 1 131 4 Size and density population Patterns of dispersal Understand that populations can be described by size density dispersal and survivorship o Increases by cid 224 birth and immigration influx of new individuals from other areas o Decreases by cid 224 death mortality and emigration the movement of individuals out of a 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 cid 224 a plot of the proportion or numbers in a group still alive at each age Y cid 224 number of surviors X cid 224 age 3 Scarlet Encina flat at the start reflecting low death rates during early middle life and then drops steeply as Type I death rates increase among older age groups cid 224 mammals humans Type II intermediate constant death rate throughout the organisms life span cid 224 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 cid 224 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 Forces that influence population size cid 224 birth death immigration emigration Reproduction effects on mortality o Semelparity big bang reproduction one shot to reproduce MANY offspring and then die cid 224 Ex Agave plant stores nutrients during lifetime in desert until it has enough to reproduce and then dies o Iteroparity repeated reproduction repeated or even annual reproduction of few offspring at a time cid 224 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 Senescence Biological aging the process of aging resulting in deterioration and death 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 cid 224 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 4 Scarlet Encina Depend
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