Scarlet Encina BSC 2011 EXAM 4Lecture 26: Introduction to EcologyReading - 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 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.- 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 circulationo 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 theequator tropicso 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. 1Scarlet 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 currento 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 vegetationLecture 27- Populations and Life HistoryReading 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/xx/n = m/N 7/44 = 180/NN = 180 * 44/7 = 1,131.4- Understand that populations can be described by size, density, dispersal, and survivorship.- Size and densityo Increases by birth and immigration (influx of new individuals from other areas) 2Scarlet Encina o Decreases by death (mortality) and emigration (the movement of individuals out of a population)- Patterns of dispersalo 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.- SurvivorshipSurvivorship 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.3Scarlet Encina - Forces that influence population size birth, death, immigration, emigration- Reproduction effects on mortalityo 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 enough to reproduce, and then dies.o Iteroparity/ repeated reproduction: repeated or even annual reproduction of few offspring at a time. Ex: lizardso 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 reproductiono A parent’s survival might decrease by caring for young.Ex Kestrel birds- Tradeoffs b/w offspring size and numbero Plants/animals whose young are subject to high mortality rates often produce
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