Bio 94 Intro to Evolutionary Ecology - Biology 94 Ecology 1 The Study of Ecology Ecology is the study of the interactions living things have with each

Bio 94 Intro to Evolutionary Ecology - Biology 94 Ecology 1...

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1 Biology 94 Introduction to Evolutionary  Ecology
The Study of Ecology 2 Ecology is the study of the interactions living things have with each other and with their environment. Ecology versus environmentalism. Ecologists work on many levels of the biological sciences from molecules to ecosystems The ecological sciences are heavily intertwined by basic evolutionary principles
Ecology and Evolution: A very tight partnership Ecology : Considers the proximal goals of life (an individual’s survival and reproduction). Evolution : Considers the ultimate goals of the species (persistence). These two elements are inextricably interconnected. Both must be considered to really understand why a species is the way it is (its phenotype) 3
Ecologists work in one or more levels 4 There are five scales of life that concern ecology: Organism : the unit organism Population : group of organisms of the same species living in one location Community : populations of different species living in one location Ecosystem : the physical ( abiotic ) and biological ( biotic) components of a habitat the biosphere : all locations on Earth where life exists
5 Levels within ecology Figure 33.2 organism (sea lion) population (colony) community (giant kelp forest) ecosystem (Southern California coast) biosphere (Earth)
Let’s first look at Populations 6 Populations experience changes in their size over time. Intrinsic factors (such as reproductive rates) and extrinsic factors (such as food availability or predators). When studying changes in population size, we refer to ‘N’ (population size), or more precisely, ∆N/∆t (change in population size over a change in time). AKA, dN/dt
Positive and negative population growth 7 Two general factors increase a population size: births (b) and immigrations. Two factors decrease population size: deaths (d) and emigration. For a population that is closed (nobody in, nobody out) only births and deaths affect the population size at any time. The graph below shows three linear (arithmetic) models of population growth. N Time b>d b=d b<d 3 possible  situations  regarding  ∆N/∆t
Arithmetic and Exponential Growth 8 An arithmetical increase occurs when, over a given interval of time, an unvarying number of new units is added to a population. An exponential increase occurs when the number of new units added to a population is proportional to the number of units that exists…. percent growth.
9 Arithmetic and Exponential Growth 25,000 256,000 exponential growth of water-flea population arithmetic growth of car production Consequence:  Overproduction of offspring and a struggle for existence

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