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Unit One “An Introduction to Environmental Science” Reasons for and Purpose of Environmental Science • Environment – sum total of one’s surroundings; two categories that compose “surroundings” – Biotic Factors – living organisms both plant (flora) and animal (fauna) – Abiotic Factors – nonliving things such as water, air, and soil Reasons for and Purpose of Environmental Science cont’d • Environmental Science studies how the natural world functions and the specific interactions between humans ( Homo sapiens) and their surroundings • It is highly interdisciplinary and incorporates subjects such as: biology, ecology, geology, meteorology, oceanography, limnology, sociology, and public policy…. Reasons for and Purpose of Environmental Science cont’d • If humans did not have an impact on the natural world there would most likely not be the discipline of Environmental Science • Humans impact the earth specifically through the extraction/acquisition of resources • Resources – various substances found in nature that are needed for survival and comfort Reasons for and Purpose of Environmental Science cont’d • Two types of resources: – Renewable resources – unlimited supply assuming wise use (these resources are usually biotic) • Example – Nonrenewable resources – limited supply (these resources are abiotic) • Example Reasons for and Purpose of Environmental Science cont’d • The goal of an environmental scientist is to understand how humans impact the earth (both negatively and positively). Additionally, if there are any negative impacts, environmental scientists research and implement ways to mitigate those impacts • Environmental Science IS NOT the same as Environmentalism • Environmentalism is a social movement dedicated to the preservation of the natural world; this movement began in the early 1970’s with the celebration of the 1st Earth Day The “Science” behind Environmental Science • In order to properly conduct scientific research of any kind the scientific method must be employed • There are 5 steps to this method • What are the steps? – – – – – 1) State problem 2) Formulate hypothesis 3) Experiment 4) Analyze results 5) Conclusion The “Science” behind Environmental Science cont’d • When research/experiments are conducted, quantitative data and not qualitative data must be collected • The collection of quantitative data allows the scientist to remain objective in the reporting of his/her data – Quantitative = Objective – Qualitative = Subjective The “Science” behind Environmental Science cont’d • Bias should be avoided • Control(s) should be used in experiments for the purpose of comparison • Variables that would negatively affect results of an experiment should be eliminated • Independent variable – variable scientist manipulates (example: time) • Dependent variable – it’s outcome depends on independent variable (example: temperature) • http://www.biologycorner.com/worksheets/ controls.html Data should be plotted on a graph The “Science” behind Environmental Science cont’d • Step 2 of Scientific Method requires one to form a hypothesis a.k.a. “educated guess” • Step 5 of Scientific Method requires one to support or not support the hypothesis made in step 2 based on data obtained in step 3 • If experiment is deemed worth by peers it can be published in one of numerous scientific journals for the purpose of disseminating information/knowledge Unfortunate Reality in Science • One in seven scientists say they are aware of colleagues that have invented results • Dishonesty and misrepresentation are widespread due to several factors: – Inherent bias – Professional pressure – Monetary gain “One in Seven Scientists Say Colleagues Fake Data” in The Times; June 5th, 2009 The “Science” behind Environmental Science cont’d • Theory - statement based on a large supporting body of evidence; is more accepted in scientific community than a hypothesis – “Evolution” • Law – scientific fact – “For every action there is an equal and opposite reaction” Current State of Affairs • Is our planet healthy? Are we having a net negative impact on the Earth? • The above questions will be addressed/discussed throughout the semester Unit One “Biology Basics” “Evolution, Biodiversity, and Population Ecology” Concepts surrounding Evolution • Evolution – the change in the genetic composition of a population over time due to chance alone • Natural Selection – the process by which mutations create certain traits that are more suited to an environment than other traits • Adaptation – individuals that possess those traits that are more suited to the environment survive and generally thrive Concepts surrounding Evolution cont’d • Mutation – a random change in the genetic code (DNA/RNA) • These mutations lead to the development of new traits both helpful and detrimental to a species • Charles Darwin was the first person known to propose these concepts; voyage of the HMS Beagle in the 1800’s • http://history1800s.about.com/od/innovators/a/h msbeagle.htm Concepts surrounding Evolution cont’d • Evolution leads to biological diversity • Biodiversity is the variety of life in an ecosystem or defined area • Areas with high biodiversity are called hot spots; these areas are usually in regions with a moderate climate Biodiversity Hot Spots (red) Concepts surrounding Evolution cont’d • Speciation leads to many new species several of which may be wiped out by an extinction event • Extinction causes the disappearance of many species but also allows for the evolution of many new species • Extirpation is the extinction of a species in a specific area • All past mass extinctions were most likely due to catastrophic natural occurrences like Ice ages, meteorites, and volcanic eruptions Levels of Ecological Organization • Ecology – study of the biotic and abiotic factors in an area • Species - organisms that look similar and can breed to produce reproductively capable offspring • Population – a group of individuals of the same species living together • Community - several populations that live in the same area Levels of Ecological Organization cont’d • Ecosystem – a defined area with a specific set of biotic and abiotic factors; usually defined by vegetative associations • Speciation is demonstrated by using a Phylogenetic Tree • Habitat versus Niche – habitat is where an organism lives a niche is how an organism lives in its habitat Levels of Ecological Organization cont’d • Specialist versus Generalist - a specialist requires a specific set of resources whereas a generalist can live off a broader range of resources – Example: Scrub Jay and Raccoon Population Ecology • Population Ecology – study of the dynamics of populations such as density, distribution, sex ratio, age structure, and mortality/natality – Population density – how many individuals there are of a species per unit area – Population distribution - spatial arrangement of individuals within an area Population Ecology cont’d • Survivorship curves – show the distribution of ages across a population; predicts the likelihood of death at various ages per species Population Ecology cont’d • Immigration versus Emigration – How many enter an area versus how many leave an area – Formula for Growth Rate (Birth Rate + Immigration Rate) – (Death Rate + Emigration Rate) = Growth rate Population Ecology cont’d • Population growth is dependent on biotic potential • Some species can reproduce many offspring per reproductive event, and can have several reproductive events per year • Those species that fit into the above-mentioned category are “r – selected”: mice and rabbits • Species that seldom reproduce, and when they do reproduce only have one or two offspring are “k-selected”: whales and humans Population Ecology cont’d • Limiting Factor – a resource that prevents a population from increasing in size • Carrying Capacity – total number of individuals an ecosystem can sustain based on resource availability • Limiting factors can vary from ecosystem to ecosystem and populations of different species can vary in size within the same ecosystem • What are some examples of limiting factors? Population Ecology cont’d • Exponential Growth – the global human population began to increase rapidly at onset of the Industrial Revolution but has since slowed appreciably with growth only continuing in less developed nations • Now there is a population paradox globally – will discuss human population in unit 2