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INTRODUCTION

INTRODUCTION. Chapter 1. Preface: J.R. Platt 1964. Strong Inference. Science 146:347-353. Yes! The paper is sexist in a few places. In 1964, mostly, science was done by men. Times have changed. Looking beyond this annoying feature of the paper,….

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INTRODUCTION

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  1. INTRODUCTION Chapter 1

  2. Preface: J.R. Platt1964. Strong Inference. Science 146:347-353 • Yes! The paper is sexist in a few places. In 1964, mostly, science was done by men. Times have changed. Looking beyond this annoying feature of the paper,…. • Presents a passionate plea for rigorous use of the scientific method. • Platt was not an ecologist and he argues that some fields of science are making more rapid progress because they follow the scientific method more effectively. • The use of Inductivereasoning.

  3. Inductive reasoning:Start with a specific observation and move towards a general conclusion • Given a specific observation: • 1. Devise alternative hypotheses; • 2. Devise a crucial experiment (or several of them) , with alternative possible outcomes, each of which will, as nearly as possible, exclude one or more of the hypotheses; • 3. Carry out the experiments repeating as needed to get clean, consistent results; • 1’. Recycle the procedure, making sub-hypotheses or sequential hypothesis to refine the possibilities that remain…..

  4. Strong Inference • Platt likens this to the process of climbing a tree. At each fork, we choose a path and climb to the next fork. • A key component of this process is the use of multiple working hypotheses. Don’t become too attached to your “favorite” explanation. • Science makes progress by disproving alternative hypotheses. We never, ever, prove anything in science.

  5. An Example: The White Swan Hypothesis • “All swans are white.” • Repeated observations throughout North America, Europe and Asia are consistent with this hypothesis, however, this does not prove the hypothesis. Failure to disprove is not proof. • All it takes is a single observation of a non-white swan to disprove this hypothesis

  6. The Black Swan (Cygnus atratus) Western Australia

  7. “But it’s only a theory” • A theory is far more than a half-baked idea. • An hypothesis gradually gets transformed into a theory as it withstands multiple attempts to disprove it. • However, “a theory which cannot be mortally endangered” (cannot be tested) “cannot be alive.”

  8. Platt’s “The Question” • What experiment could disprove your hypothesis?

  9. Introduction • Ecology: Study of relationships between organisms and the environment. • Simple definition does not convey the extreme breadth of this discipline. • What do ecologists do? • Some examples……

  10. Ecology of Forest Birds • MacArthur – studied ecology of five species of warblers in spruce forests in N.A. • Theory predicted two spp. with identical ecological requirements could not coexist indefinitely. • Warblers did coexist by feeding in different zones of trees. • Stimulated competition research.

  11. Why do these differences exist? Is it competition? How would you test this?

  12. This observation is consistent with the competition hypothesis but it is not “proof.”

  13. Ecology of Bumblebees • Heinrich estimated energy budget of bumblebees foraging on different flowers and under different temperatures. • Energy Gain/Loss: • Energy Intake – Energy Expenditure • Amount of energy expended during flight was independent of air temperature and bees elevated temp. of thorax to stay warm in cool climates.

  14. Forest Nutrient Budgets • Nalini Nadkarni: Nutrient stores in rainforest canopies are associated with epiphytes (plants living on branches / trunks of other plants). Mass of epiphytes is 4X the mass of leaves of host trees in forests on the Olympic Peninsula of WA • Epiphyte mats create small diverse communities. • Trees send roots up to epiphyte mats to access nutrients.

  15. Forest Nutrient Budgets - cont. • Likens and Bormann estimated 90% of nutrients in a New Hampshire forest were locked up in soil organic matter. Approximately 9.5 % was tied up in vegetation, and rest was lost by streamflow output.

  16. Vegetation Change: Pollen Records • Many env. changes take place over large spatial scales and/or temporal scales. • Davis monitored plant pollen deposited in lake sediments in the Appalachian Mtns. • Documented large temporal changes to nearby plant communities.

  17. Nature and Scope of Ecology • Ecology: Study of relationships between organisms and the environment. • Wide variety of approaches. • Large range of temporal and spatial scales. • Field • Lab • Observational • Manipulative

  18. Nature and Scope of Ecology Kimmins 1997

  19. Major Premise Of This Book: Modern Ecology was built on a strong foundational knowledge of natural history. Furthering knowledge of natural history improves our understanding of ecological relationships.

  20. Origins of Ecology • The word ECOLOGY was coined by Ernst Haeckel in 1869. It is derived from the Greek oikos, meaning "household", "home," or "place to live" and logos, "the study of.“

  21. More definitions for Ecology • "...the investigation of the total relationships of the animal both to its inorganic and its organic environment..." (Haeckel 1869) • "...scientific natural history." (Elton 1927) • "...the scientific study of the distribution and abundance of animals." (Andrewartha 1961) • "...the study of the structure and function of nature" (Odum 1971) • "...the study of the adaptations of organisms to their environment" (Emlen 1973)  • "...the scientific study of the relationships between organisms and their environments" (McNaughton and Wolfe 1979)

  22. More definitions for Ecology • "...the scientific study of the interactions that determine the distribution and abundance of organisms." (Krebs 1985)  • "...the study of the principles which govern temporal and spatial patterns for assemblages of organisms" (Fenchel 1987)  • "...the study of the relationships between organisms and the totality of the physical and biological factors affecting them or influenced by them" (Pianka 1988)

  23. More definitions for Ecology • A common thread in many of these definitions is that: The Environment influences Organisms AND Organisms influence the Environment • The fact that the atmosphere contains 21% oxygen is a striking example of the power of organisms (green plants) to influence the environment.

  24. The history of Ecology • Rooted in natural history and efforts to understand the distribution and abundance of animals and, to a lesser extent, plants too. • The Greeks and much later, Europeans, were strong believers in the balance of nature or "providential ecology"-- the notion that nature is designed for the benefit of each species, or at the very least, for the benefit of humans. • This "balance of nature" view prevailed for a very long time. You can even see a bit of this in some modern natural history writing but this is no longer seen in mainstream scientific writing.

  25. Challenges to the Balance of Nature View • 1. Dinosaurs! Fossils discovered during late 1700s and early 1800s. Why is this a problem? • 2. Thomas Malthus, an economist who wrote “An essay on populations” in 1798.He made two key observations: • The number of humans can potentially increase at a geometric rate through time, but; • The food supply is likely to increase at only a linear rate at best • Malthus concluded that human populations would be kept in check by food supply and there would be intense competition for that food supply. • The result: Intense social strife and war. Malthus’ book was a bombshell! • Though Malthus intended his ideas to be applied to human societies, could this idea be relevant to other animals and plant communities?

  26. An alternative to the Balance of Nature:Charles Darwin • 1858: Charles Darwin and Alfred Wallace independently develop and publish a theory on the evolution of species through natural selection • The voyage of the Beagle: the ultimate internship • Dawin read Malthus upon his return and applied these ideas to observations made during his voyage.

  27. Charles Darwin • By applying Malthus' logic to the natural world, Darwin noted that overproduction of young would lead to intense competition, heavy mortality, and therefore to a "natural" selection process. • Darwin’s great insight was that, given sufficient time, one species might split into several new species, each with adaptations shaped by the selective pressures of climate, food supply, predation and competition.

  28. Charles Darwin’s book, On the Origin of the SpeciesPublished in 1859 • A key argument in his book was the emphasis oncompetition between individuals of the SAME SPECIES as the chief mechanism of evolutionary change. • It had long been acknowledged that predators prey most heavily on the old, weak or diseased individuals. This was viewed as a “good” thing since it preserved the character of the prey population. • These authors failed to see, as Darwin did, the potential that competition within a population could have for producing real change in the character of the population. • Natural selection is therefore a creative force, not one that merely preserves the character of a species.

  29. Darwin’s ideas have gained widespread acceptance and they have fundamentally changed the way we view the natural world

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