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Biology 2483A
Hugh Henry

The Web of Life Slide1: ● Ecology: scientific study of interactions between organisms and their environment (includes interactions between one another); study that determines the distribution (geographic location) and abundance of of organisms ● Natural systems are driven by the ways in which organisms interact with one another and with the physical environment Slide2: ● Public and professional ideas about ecology often differ ○ Misconception 1 cleared: now we recognize that, natural systems don’t return to their original state after a disturbance; seemingly random perturbations often play an important role in nature; different species in an area often respond in different ways to changing conditions ○ Misconception 2 cleared: the view that each species has a distinct function can lead people to think that each species is important and irreplaceable, which can cause people to think that it is wrong to harm other species ○ Connections doesn’t mean they are strong among all of the organisms; but all organisms are connected to features of their environment (ex. food, space, other resources) ○ events in nature are interconnected; change in one part can affect other parts (including those that govern life supporting processes like purification of air, water, and soil) ● The scale of an ecological study affects what can be learned from it ; when studying birds, we don’t care about ponds; when studying microorganisms the scale is a lot smaller than when studying atmospheric pollutants Slide3: ● Ecological Maxims ○ Organisms interact and are interconnected; as a result events in nature are connected and what affects one org can affect others as well; life would be impossible without species interaction, species depend on on another for energy, nutrients and habitat ○ Everything goes somewhere; there is no “away” into which waste materials disappear; ex. pollution, nutrients ○ No population can increase in size forever; there are limits to the growth and resource use of every population, including our own ○ Finite energy and resources results in tradeoffs; increasing inputs to one function (such as reproduction) can result in a trade off in which there is a loss for other functions (such as growth) ○ Organisms evolve; they are not static. organisms continually face challenges from both abiotic and biotic components in their environment ○ Communities and ecosystems change over time; when we look at the world as we know it, it is easy to forget how past events may have affected our present and how our present actions may affect the future ○ Spatial scale matters; abiotic and biotic environmental conditions can change dramatically from one place to another, sometimes across very short distances. this variation matters because organisms are simultaneously influenced by processes acting at multiple spatial scales, from local to regional to global Slide4: ● Ecological hierarchy: life in the Sonoram desert can be studied at a number of levels from individuals to the biosphere. these levels are notes within one another, in the sense that each level is composed of groups of the entity found in the level below it Slide5: ○ Population: Group of individuals of a species that are living and interacting in a particular area ○ Community: Association of populations of sifferent species in the same area ○ Ecological studies often include both the biotic (living) and abiotic (nonliving) components of natural systems ○ Ecosystems: Community of organisms plus the physical environment ○ Landscapes: Areas with substantial differences, typically including multiple ecosystems ○ All the world’s ecosystems comprise the biosphere - all living organisms on Earth plus the environments in which they live Slide6: ○ Adaptations: A characteristic that improves survival or reproduction ○ Natural selection: Individuals with certain adaptations tend to survive and reproduce at a higher rate than other individuals ○ If the adaptation is heritable, the frequency of the characteristic may increase in a population over time ○ adaptations drive natural selection ○ Evolution: a change in the genetic characteristics of a population over time; descent with modification, the proces by which organisms gradually accumulate differences from their ancestors Slide7: ● Ecosystem processes ○ Producers: capture energy from an external sourse (ex. sun) and use it to produce food ○ Net primary productivity (NPP): Energy captured by producers, minus the amount lost as heat in cellular respiration; NPP varies greatly from one ecosystem to another; changes in NPP have large effects on ecosystem function ○ Consumers: get energy by eating other organisms or their remains Slide8: ● How ecosystems work ○ energy moves through ecosystems in a single direction only - it cannot be recycles ○ but nutrients are continuously recycles from the physical environment to organisms and back again - this is the nutrient cycle Slide9: ● Ecological experiments can be done at different scales ○ when you have experiments in a lab, it’s not real, although you can control many more things,
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