BIO 311D 1st Edition Lecture 35 Outline of Last Lecture I Competition II Ecological Niches and Natural Selection III Character Displacement IV Predation V Species Diversity VI Diversity and Community Stability VII Tropic Structure VIII Food Webs Outline of Current Lecture I Life history traits are products of natural selection II Evolution and Life History Diversity III Trade offs and Life Histories IV Overview Discovering Ecology V The Scope of Ecological Research VI Global Ecology VII Landscape Ecology VIII Ecosystem Ecology IX Earth s climate varies by latitude and season and is changing rapidly Current Lecture The logistic model fits few real populations but is useful for estimating possible growth Conservation biologists can use the model to estimate the critical size below which populations may become extinct Life history traits are products of natural selection An organism s life history comprises the traits that affect its schedule of reproduction and survival The age at which reproduction begins How often the organism reproduces How many offspring are produced during each reproductive cycle Life history traits are evolutionary outcomes reflected in the development physiology and behavior of an organism Evolution and Life History Diversity Species that exhibit semelparity or big bang reproduction reproduce once and die Species that exhibit iteroparity or repeated reproduction produce offspring repeatedly Highly variable or unpredictable environments likely favor big bang reproduction while dependable environments may favor repeated reproduction Trade offs and Life Histories Organisms have finite resources which may lead to trade offs between survival and reproduction For example there is a trade off between survival and paternal care in European kestrels Some plants produce a large number of small seeds ensuring that at least some of them will grow and eventually reproduce Other types of plants produce a moderate number of large seeds that provide a large store of energy that will help seedlings become established K selection or density dependent selection selects for life history traits that are sensitive to population density r selection or density independent selection selects for life history traits that maximize reproduction The concepts of K selection and r selection are oversimplifications but have stimulated alternative hypotheses of life history evolution Overview Discovering Ecology Ecology is the scientific study of the interactions between organisms and the environment These interactions determine the distribution of organisms and their abundance Modern ecology includes observation and experimentation The rediscovery of the nearly extinct harlequin toad in Costa Rica raises many ecological questions What environmental factors limit their geographic distribution What factors food pathogens affect population size The Scope of Ecological Research Ecologists work at levels ranging from individual organisms to the planet Global Ecology The biosphere is the global ecosystem the sum of all the planet s ecosystems Global ecology examines the influence of energy and materials on organisms across the biosphere Landscape Ecology A landscape or seascape is a mosaic of connected ecosystems Landscape ecology focuses on the exchanges of energy materials and organisms across multiple ecosystems Ecosystem Ecology An ecosystem is the community of organisms in an area and the physical factors with which they interact Ecosystem ecology emphasizes energy flow and chemical cycling among the various biotic and abiotic components Community Ecology A community is a group of populations of different species in an area Community ecology deals with the whole array of interacting species in a community Population Ecology A population is a group of individuals of the same species living in an area Population ecology focuses on factors affecting population size over time Organismal Ecology Organismal ecology studies how an organism s structure physiology and for animals behavior meet environmental challenges Organismal ecology includes physiological evolutionary and behavioral ecology Earth s climate varies by latitude and season and is changing rapidly The long term prevailing weather conditions in an area constitute its climate Four major abiotic components of climate are temperature precipitation sunlight and wind Macroclimate consists of patterns on the global regional and landscape level Microclimate consists of very fine patterns such as those encountered by the community of organisms underneath a fallen log
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