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Ecology

Ecology. Campbell, Chapters 50-54. Ecology v. Environment. Hierarchy of Ecology biosphere ecosystem community population organismal. Biotic and Abiotic Factors. components of the environment biotic other species may affect one species and its distribution abiotic temperature water

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Ecology

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  1. Ecology Campbell, Chapters 50-54

  2. Ecology v. Environment • Hierarchy of Ecology • biosphere • ecosystem • community • population • organismal

  3. Biotic and Abiotic Factors • components of the environment • biotic • other species may affect one species and its distribution • abiotic • temperature • water • sunlight • Wind • rocks and soil

  4. Population Ecology • Density • mark and recapture method • line intercept method • point count method • Distribution • clumped • uniform • random

  5. Age Distribution • distribution of males and females in each age group of a population • used to predict future population growth

  6. Survivorship • mirrors mortality • expressed in survivorship curves • plots surviving individuals at different age groups • three types of survivorship curves • late loss (Type I) • constant loss (Type II) • early loss (Type III)

  7. Population Dynamics: Exponential Model • population lives in an area with no environmental limitations • example • # of births over one year is 500 and # of deaths over one year is 50 B = number of births in time period D = number of deaths in time period

  8. Population Dynamics: Exponential Model • per capita rate of increase • average number of births and deaths calculated as rates • J curve • exponential growth

  9. Population Dynamics: Exponential Model • example • 10,000 birds in a population • 1500 births and 500 deaths per year • 1500/10,000 - 500/10,000 = .10 or 10% • expressed by stating there is a 10% increase per bird per year

  10. Population Dynamics: Exponential Model • measures optimal population growth • rmax = intrinsic rate of increase • example • if N=500; r=.05 Calculate the intrinsic rate of increase

  11. Population Dynamics: Logistic Growth Model • size of a population is limited to: • intrinsic rate of increase • environmental resistance • includes limitations the environment imposes on birth rate and death rate in a population • food • space • predation • Parasitism • carrying capacity (K) determined by • renewable resources like water, nutrients, and light • nonrenewable resources such as space

  12. Population Dynamics: Logistic Growth Model • logistic population growth • r decreases as N increases • K-N tells us # of individuals population can accommodate • S curve

  13. Logistic Growth Model and Life Histories • K-selected • equilibrial populations • live at density near limit imposed by resources • r-selected • opportunistic populations • live in environments where little competition is present

  14. Density Influence on Birth and Death Rates • density independent • unrelated to population size • most important are • weather • Climate • density dependent • increase effectiveness as population density increases • especially affects long lived organisms • include • predation • parasitism • competition

  15. Human Population Growth • J curve growth • grows at a rate of about 80 million yearly (r=1.3%) • Why doesn’t environmental resistance take effect? • altering their environment • technological advances • the cultural revolution • the agricultural revolution • the industrial-medical revolution

  16. Community Ecology • competition • predator-prey • symbiosis • mutualism • commensalism • parasitism • amensalism • species richness • relative abundance • species diversity

  17. Competition • intraspecific competition • interspecific competition • Competitive exclusion principle

  18. Predator-prey Interactions • one species eating another • herbivory • carnivory • parasitism • cannibalism • predators are agents of natural selection • animal defenses against predators • hiding or escape • mimicry • adaptive coloration

  19. Mimicry • Batesian mimicry

  20. Mimicry • Müllerian mimicry

  21. Mimicry • aggressive mimicry

  22. Adaptive Coloration • cryptic coloration

  23. Adaptive Coloration • deceptive coloration

  24. Adaptive Coloration • aposematic coloration

  25. Symbiosis • involves • host • symbiont • 3 divisions • mutualism • commensalism • parasitism Mutualism - lichens

  26. Symbiosis • involves • host • symbiont • 3 divisions • mutualism • commensalism • parasitism Commensalism – sea slug and chloroplasts

  27. Symbiosis • involves • host • symbiont • 3 divisions • mutualism • commensalism • parasitism Parasitism – Chagas’ Disease

  28. Coevolution • reciprocal evolutionary change • e.g. flower shape and pollination • creates a “balance of nature”

  29. Moderator of Competition • keystone species • removal dramatically alters the environment • influences species diversity

  30. Trophic Structure • feeding relationships • trophic levels • primary producers • primary consumers (herbivores) • secondary consumers (primary carnivores) • tertiary consumers (secondary carnivores) • detritovores • omnivores • food chain vs. food web

  31. Food Chain v. Food Web

  32. Ecological Succession • structural change in a community and its nonliving environment over time • typically occurs as a result of some environmental disturbance • 2 forms • primary succession • begins in a lifeless area with invaders called pioneers • may proceed to a stable climax community • vary according to geography, climate, etc • secondary succession • occurs in an existing community where a disturbance has occurred

  33. Ecosystem Processes • Production • Consumption • Decomposition Trophic Relationships exhibit all 3 processes • autotrophs produce • heterotrophs consume • detritovores and decomposers recycle and decompose

  34. Production: Energy Flow • light energy • about 1% of sun’s energy used for life • converted via photosynthesis • How do we measure the amount of energy incorporated by producers? • primary production

  35. Consumption: Energy Flow • ecological efficiency • 10% on average • energy pyramid • biomass pyramid

  36. Nutrient Cycles • Biogeochemical cycles • materials move through biotic and abiotic portions • reservoir

  37. Biogeochemical Cycles • Be able to answer the following questions about each biogeochemical cycle • 1. What is the reservoir? • 2. How does the nutrient enter the biotic portion of the cycle? • 3. How is the nutrient returned to the reservoir?

  38. Biological Magnification • toxic substances accumulate in higher concentrations as trophic levels increase • toxin is usually not biodegradable • result of inefficiency of energy transfer

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