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Definition of Ecology

Definition of Ecology 1866 Ernst Haeckel: the comprehensive science of the relationship of the organism to the environment 1927 Charles Elton: Scientific natural history 1963 E. P. Odum: The study of the structure and function of nature

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Definition of Ecology

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  1. Definition of Ecology • 1866 Ernst Haeckel: the comprehensive science of the relationship of the organism to the environment • 1927 Charles Elton: Scientific natural history • 1963 E. P. Odum: The study of the structure and function of nature • 1972 C. J. Krebs: The scientific study of the interactions that determine the distribution and abundance of organisms

  2. Ecological spectrum Biosphere, Landscape, Ecosystem, Community, Population, Organism, Organ system, Organ, Tissue, Cell, Subcellular organelles, Molecules Branches of Ecology Chemical, Molecular, Physiological, Behavioral, Population, Community, Ecosystem, Landscape, Evolutionary, Theoretical, Conservation and management, Biodiversity

  3. Journals: Behavioral Ecology, Biological Conservation, Chemical Ecology, Conservation Biology, Conservation Ecology, Ecological Application, Ecological Modeling, Ecological Monograph, Ecologist, Ecology, Environmental Management, Evolutionary Ecology, Functional Ecology, Journal of Animal Ecology, Journal of Applied Ecology, Journal of Wildlife Management, Landscape Ecology, Molecular Ecology, Oecologia, Oikos, Trends in Evolution and Ecology, etc.

  4. Methods of studying ecology • To understand, describe, explain, predict and control • Scale • Lab experiment, field experiment, natural trajectory experiment, natural snapshot experiment, mathematical model

  5. Ecology of forest birds • 5 warbler sp. of similar ecological requirement • Feeding zones • In the presence or absence of other species • Competition and partitioning

  6. Energy budget of bumblebee • How to keep warm in cold environment? • Energy gain for feeding – energy loss from flying, feeding and keeping warm • Lab and field studies • Number and kinds of flower visited, sugar content of flower • Energy loss at different temperature

  7. Brown trout v.s. Native Galaxias • Fish → Mayfly nymph → algae • Activity pattern (lab and field exp.) • Habitat preference (natural exp.) • Community effect (field exp.)

  8. Trophic cascade – effects flowing down from one trophic level to the next and the next • Energy flow • Primary production: trout >> Galax • Secondary production: trout >> Galax

  9. Succession of old fields • Natural trajectory vs. natural snapshot • Correlation vs. mechanism • within field comparison indicated introduced sp.↑andprairie sp.↓ as N↑ • Field experiment • sp. composition and N supply

  10. Nutrients in the rain forest canopy • Epiphytes mats ~ ½ to 4x of the nutrient content of the foliage of the canopy trees • Photosynthesis, migratory birds, bats

  11. Fox-rabies (math model) • Assumptions: no recovery or immune, no migration, random contact • Biology: life span 2 yrs., 1 cub/yr, latent phase 28 days, die 5 days after becoming infectious

  12. N = S + L + I dS/dt = (b-d)S -αSI dL/dt = αSI - dL - βL dI/dt = βL - dI - γI α - contact rate β - reaction rate γ - rabies-induced mortality

  13. Merits of model • Summarizing current knowledge • Approximation and simplification • Hypotheses testing • Exploring scenarios and situations • Caution in evaluation and prediction

  14. Factors affecting the abundance and distribution of species • Historical factors • evolution and speciation • continental drift • geological and climatic changes • Abiotic factors • chemical and physical environment

  15. Biotic factors • competition, predation, mutualism, etc. • Dispersal • Behavioral factors • Human factors

  16. Darwinian evolution by natural selection • individual variation • variation is heritable • differential reproductive rate • the interaction between the characteristics of individual and the environment

  17. Fitness • a measure of biological success • # of gene or genome put into the next generation • the proportionate contribution that an individual makes to future generation

  18. The fittest individual • those that leave the greatest # of descendants • those that transport more gene to the next generation

  19. Example • Model: an annual, only one gene, asexual reproduction, reproduce only once in life time. • 5 genotypes: A, B, C, D, and E • G, S, F = proportion of energy devoted to growth, survival (against predator), and fecundity

  20. # of seed Genotypes Spring/Summer Fall Survival 10 A 2 large 2 seeds 4 10 B 9 small 1 seeds 9 10 C 2 small 4 seeds 8 10 D 4 medium 5 seeds 20 10 E 5 med-small 4 seeds 20 Total 61 G:F:S in A=6:1:1, B=1:1:6, C=1:6:1, D=1:1:1, E=1:1:2

  21. Genotype frequency before after one generation A 10/50=0.2 4/61=0.06 B 0.2 9/61=0.15 C 0.2 8/61=0.13 D 0.2 20/61=0.33 E 0.2 20/61=0.33 Fitness = # of gene/genome put into the next generation Fitness of D&E = 20/10 = 2 Fitness of C = 8/10 = 0.8 Fitness of B = 9/10 = 0.9 Fitness of A = 4/10 = 0.4

  22. Questions • Is the population biologically successful? • Are those genotypes equally successful? • What if increase herbivory?

  23. Within species variation • Perennial Achillea lanulosa, transplant and reciprocal transplant • Natural selection by pollution • Industrial melanism • Natural selection by predation

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