ScienceandEcology.pdf Biol 105-01
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This 16 page Class Notes was uploaded by Caitlyn Windhorst on Friday February 5, 2016. The Class Notes belongs to Biol 105-01 at Slippery Rock University of Pennsylvania taught by Dr. Dean Denicola in Spring 2016. Since its upload, it has received 22 views. For similar materials see Environmental Biology in Biology at Slippery Rock University of Pennsylvania.
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Date Created: 02/05/16
Science Science: making precise observations of natural phenomena and formulating rational theories to make sense of those observations Assumptions The world is knowable Basic patterns that determine events do not change in time or space When two explanations for a phenomenon are possible (the simplest one applies) Theories are considered correct until disapproved Inquiry Discovery Science o Describing nature o Lead to generalizations based on large numbers o Inductive reasoning from specific to general (cell theory) organism 1 – made of cells organism 2 – made of cells organism 3 – made of cells generalization= all organisms made of cells HypothesisBased o Mostly about explaining nature o Search for the cause o Proposal and testing of hypothesis Deductive reasoning: a general statement to explain specific observations o General all insects have six legs o Specific new organism has six legs. New organism is an insect Hypothesis o A provisional explanation that can be falsified by further investigation Has to be testable Observations form testable hypothesis collect data (usually involves experiment) interpret results (if no, form a new testable hypothesis, if yes, continue) report for peer review publish findings Scientific Theories Theory – an explanation that is broad in scope, generates new hypothesis, and is supported by a large body of evidence o A nonscientist – a guess because of lack of knowledge o Science – close to truth Naturalist Science Experimentation may not be possible Examples: astronomy, geology, evolution Scientific method is still followed Hypothesis testing is with more observations Pseudoscience Provides a framework for distinguishing between what’s scientific and what’s not Examples: astrology, homeopathy, numerology, intelligent design, creationism Limitations of Science Not: o Religion (faith) o System of ethics (right/wrong) o Esthetics (beauty) Ecology Scientific studies of the relationships between organisms or groups of organisms and their environment Environment: the abiotic and biotic conditions that surround an organism or group of organisms Origins of Environmental Awareness 1 stage: pragmatic utilitarian conservation (wise use of resources) o George Perkins Marsh – “Man and Nature” (1864), “Earth Modified by Human Action” (1874) o Aldo Leopold – “Sandy County Almanac” (1949), “Land nd Ethic” 2 stage: biocentric preservation (wilderness should be preserved for own sake) o Ralph Waldo Emerson o Henry David Thoreau o John Muir (naturalist) o Aldo Leopold rd 3 stage: concern about rising pollution (environmentalism) o Aldo Leopold o Rachel Carson – “Silent Spring” (pesticide and water) a) human population more people more consumption more waste more pollution b) higher expectations with economic development c) technological changes (manmade materials – “Synthetic”) EPA (environmental protection agency 4th stage: global concerns and social progress Environmental Science The interdisciplinary study of complex interactions of humans with living and nonliving organisms Theory of Evolution Darwin came up with it o 5 year voyage Voyage of the Beagle 18616 Throughout Southern hemisphere (book in 1859) Species a group of organisms that can interbred and produce fertile offspring Population – a group of individuals of the same species at the same place at the same time Modern Definition of Evolution The process by which the genetic composition (traits) of a population of organisms (a gene pool) changes over time Main Points of Evolution There is a variation (traits) among individuals in a population (which can be inherited) More Individuals are born than can survive Individuals compete for resources that enable them to survive Some individuals have traits which make them better competitors, and they are more likely to survive and pass hose traits onto their offspring Ecology Organism population community ecosystem biosphere (biggest level) Autecology (Aut=self) Organismal ecology (another name) Ecology of individual organisms Population Ecology Population group of the same species at a given place and time Birth rate, space Community Ecology Group of cooccurring populations All the species in an area Ecosystem Ecology A community and its physical environment interacting in an exchange of matter and energy Organismal Ecology Basic Requirements for Life 1. Nutrients 2. Energy a. Autotrophs: get carbon from CO2 in the air i. Phototrophs: light energy, photosynthesis (sunlight + CO2 + H20 food) (molecules + O2 are byproducts of oxygen gas) b. Heterotrophs: get both energy and nutrients from eating food or other organisms i. Respiration (food molecules + reacting them with Oxygen CO2 gas + energy) 3. Water (H2O) 4. Gases (CO2 and O2) 5. Space, habitat Metabolism Overview Food molecules ATP energy and CO2 gas cell molecule Food molecules smaller organic molecules cell molecule Sunlight* and CO2 ATP energy organic molecules O2 gas and food molecules o *original source of organic molecules for every organism (except chemotrophs). 99.9% of all energy for life on Earth comes from the sun Water (H2O) Properties 1) a liquid over wide range of temperatures 2) a lot of different types of molecules dissolved in H20 [universal solvent] 3) cohesive (stick to one another) 4) solid is less dense than liquid [ice floats] 5) holds a lot of heat 6) takes a lot of water to turn water from liquid to gas Heterotrophs Herbivores, carnivores, detritivores Environmental Factors/Conditions Temperature Humidity Solidity Law of the Minimum The growth of an organism depends on the amount of resource of environmental factor that is in limiting quality Factors interact so it is hard to isolate Ecological Niche Holistic conceptualization of the ecological properties of an individual (or species) Fundamental of Requirement Niche Set of environmental conditions that permit survival and reproduction in the absence of negative interactions with other species Elton the role of organism’s in the community Realized or Impact Niche Subset of fundamental niche that permits survival and reproduction in the presence of other species Hutchinson set of resources axes Terms for Body Temperature Homeotherm – maintain constant body temperature Poikilotherm – body temp varies with environment (like a snake) Endotherm – uses metabolic heat production to regulate body temperature Ectotherm – use solar energy to regulate temp Population Ecology group of same species living at a given place or time Properties 1. distribution (arranged in environment) a. clumped b. uniform c. random 2. density i. biomass – weight mass ii. kg/km(^2) b. population size / area c. mass weight / area 3. migration – movement if individuals in and out of a population a. immigration into population b. emigration out of population dispersal no chosen direction to movement 4. birth (natality) rate – production of new individuals in the population a. birth rate = # born / unit time b. specific birth rate (b) = # born / unit time / unit of populations size 5. death (mortality rate) a. death rate = #die / unit time b. specific death rate (d) = #die / unit time / unit population size 6. survivorship – the proportion of population surviving to various ages in survivorship curves a. cohort – individuals born at the same time i. Type I – humans, most big mammals ii. Type II – birds, reptiles iii. Type III – fish, frogs, weeds, insects, invertebrates 7. Age Structure % of population at different ages a. Pyramid like structure – increasing population or expanding/ growing b. Dome like structure – not growing or increasing c. Light bulb like structure – declining in population size General Population Growth Equation r = intrinsic rate of increase = bd N = population size t = time ∆ = changing E = emigration b= specific birth rate d= specific death rate I = immigration o Rate of growth a. ∆N/∆t = b(N) – d(N) + I – E b. Change of population / change of time = (birth x population) – (death x population) + immigration + emigration o Assume I & E are 0 o ∆N/∆t = (bd)N o ∆N/∆t = rN o No limiting factors is the same as unlimited resources Limiting Resources Birth decreases, death increases, rate of growth slows down eventually to zero, and then it curves off Logistic Growth = Scurve Exponential Growth = Jcurve Carrying Capacity (K) The highest population size that can be maintained in an environment Density Independent Regulation Effect of factor does not change with population density (abiotic) Density of Dependent Regulation Effect of factor is stronger or affects more individuals as population increases (biotic) o In logistic growth Intraspecific Regulation Interactions between individuals within a population (species) Interspecific Regulations Interactions between individuals from different populations (species) Population Interactions Type Species A Species B Mutualism + + (flowers and bees) Parasitism + Predation + (wolf and rabbit) Competition (barnacles on same rock) Symbiosis = living together in close physical contact o **This is not mutualism!!!** Mutualism (+, +) An interaction between individuals on a population in which both benefit from the association o Ex) lichen (algae and fungus) o Ex) Mycorrhizae fungi and plants The plants give food and sugars to the fungi The fungi give the soil nutrients (phosphorus and nitrogen) to the plant o Ex) Nitrogen Fixing Bacteria and plants Plants give the bacteria food and sugars Bacteria give nitrogen gas from the air and makes it available to the plants o Ex) Ants and Accacia plants Competition (,) An interaction between individuals for populations created by a shared resource in limited supply, which leads to reduction in survival, growth, or reproduction of the competing organisms o Intraspecific competition logistic growth Ex) flour beetles are put into flower filled containers and they check the population growth (the jars get bigger and bigger as they add more flours and beetles) o Interspecific competition 2 outcomes (depends on how they use the shared resource) Coexist One species population goes to 0 (competitive exclusion) Ex) 2 bird species compete for seeds. They only share a certain size of seeds coexistence Ex) 2 bird species compete for seeds. they overlap the size of seeds they eat competition competitive exclusion more overlapping more competition Competitive Exclusion Principle two species with identical utilization of a limited common resource cannot coexist in the same place @ the same time o more overlap more likely to get competitive exclusion o 3 species P.A. , P.B. , P. C. P.A. vs. P.C. P.A. wins – competitive exclusion Both of them eat suspended yeast P.C. vs. P.B. Coexist P.B. eats the yeast off of the bottom Why is Competition an Important Concept??? 1. Regulates population growth 2. Determines whether species can coexist in a habitat 3. Can act as natural section force in evolution LifeHistory Strategy Life History – lifetime pattern of growth, development, storage, and reproduction Strategy – pattern of life history for a population that makes the organism better adapted for its environment over its evolutionary history 4 types of dandelions (A, B, C, D) o 3 environments Well used footpath (density independent) Moderately used footpath Old field (density dependent) Predation (+, ) Herbivory – eat plant Carnivory – eat animal Parasites – eat host (also uses it as a habitat) Amount of prey depends on: 1. Amount of prey 2. Prey size = energy content of prey 3. Search time* 4. Handling time* *optimal foraging theory: minimize energy spent to eat prey, maximize energy return Population cycles of predator and prey o Prey pop. size increases, predator pop. size increases, which causes prey pop. size decrease followed by the predator pop. size decrease continuous cycle Increase stabilization of predatorprey population cycles (factors) o Predators that are inefficient or selflimiting (ex. Grouse), they form their own territories o High prey growth rate o Refuge for prey o Predators that switch prey Coevolution of predatorprey o Natural selection of traits based on interaction between two populations Cryptic coloration Warning coloration (poisonous, often brightly colored animals) Batesian Mimicry – which a nonpoisonous organism (the mimic) resembles a poisonous one (the model) to avoid predation Ex) Monarch Butterflies (model), Viceroy and Queen (Mimics) Mullerian Mimicry – two organisms that are both poisonous resemble each other to avoid predation Ex) Cuckoo and yellow jacket Ex) most kinds of bees Community Ecology Community – group of cooccurring populations Diversity 1. Species richness # of species in the community 2. Evenness/dominance – how equal the species are in abundance Richness increases, evenness increases diversity increases Ex) Abundance % Abundance % Species Community 1 Community 2 A 20 0 B 21 0 C 19 33 D 20 33 E 20 34 Community 1 is more diverse than Community 2 Influence of Competition on Community Diversity Overlap determines how much competition If they split how much they shared, more diversity More specialization dividing up limiting resource high diversity limiting similarity, niche packing They don’t split up resource more competition, less diversity Character Displacement Changes in a physical trait as a result of natural selection to reduce competition Effect of Predation on Diversity Sea stars (starfish) eating mussels experiment done to see how mussels grew without starfish Predation Hypothesis – predation lowers prey populations and that reduces competitive exclusion Predators prevent competition exclusion among prey Disturbance A relatively discrete event that disrupts community structure and changes resources Small boulder Medium boulder Large boulder High disturbance Low disturbance Low diversity (only Enough disturbance High diversity few can survive to disrupt (competition competition exclusion) exclusion Richness Patterns Less life/species in artic, and down towards equator more species Ex) 30 in artic 180 equator Global diversity hypothesis 1. Productivity and specialization 2. Area (larger the area, the more species you have) 3. Predator Theory (# of predators) (more predators reduce competition exclusion) Succession Change in species composition in a community over time Primary Succession Succession on a site that has NOT been previously occupied by a biological community 1. Ex) volcano erupts cooled land new animals Secondary Succession Succession on a site that was previously occupied by a community but the organisms were removed by disturbance 1. Ex) forest to corn field back to forest 2. Early community – pioneer communities 3. Species replace each other – climax community Facilitation Species colonize a site and change the environment to make it less favorable for themselves and more favorable for other species
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