2IntroductionIn our first unit, we will look at making sense of the millions of organisms that live on this Earth, and their interactions.There are approximately 1.5 million different species that have been identified by scientists, of which over half are insects.Estimates are that there are over 10 million or more, that have not been identified.
3Introduction continued We need to understand organisms, not just identify them.We need to determine what it eats, how it reproduces, its habitat, interaction with other organisms and its environment.We also need to know our impact on these organisms as well.
4Definitions Ecology Ecosystem The study of the relationships between living things and their environmentA settled unit of nature consisting of a community of organisms, interacting with each other and the abiotic (non-biological) environment
5Definitions (continued) All the living organisms in a habitat or ecosystem, which is the total of all the populationsAll the living organisms of the same species in a habitat, at any one timeThe locality of physical area in which individuals of a certain species can be found. If the area is extremely small, we call it a microhabitatCommunityPopulationHabitat
6Definitions (continued) SpeciesBiomassBiodiversityA group of individuals of common ancestry that closely resemble each other and are capable of interbreeding and producing fertile offspringThe total mass or organic matterThe variety of life in an ecosystem
10Definitions Autotrophs (self feeding) Organisms that synthesize its organic molecules from simple organic substancesAlso called producersGreen plants are an example, as they produce their food (glucose) through photosynthesis
11Definitions continued HeterotrophsOrganisms that obtain organic molecules from other organismsMost of the organisms use only existing nutrients, which they obtain by digestion and then absorb into their cells and tissues for useAlso called consumers
14Definitions continued Decomposers DetrivoreSaprotrophOrganisms that ingest dead organic matter, like scavengers and earthworms(putrid feeding)Organisms that live in or on, non-living organic matter, secreting digestive enzymes into it, and absorbing the products of digestion
23Four Factors that influence a Population Natality - Birth RateMortality – Death RateImmigration – Moving inEmigration – Moving out
24Carrying CapacityPopulations cannot grow forever, and there comes a time when the growth of a population stabilizes in terms of its numbersThe number, or the maximum number of individuals that a particular habitat can support is call the Carrying Capacity (K)Limiting factors, which define the carrying capacity of a habitat include:Availability of resources, such as water, food, sunlight, shelter, space, or gases, such as oxygen in aquatic habitats
25Carrying Capacity (cont) Build up of waste, such as excrement or excess carbon dioxidePredationDisease
26Population Growth Lag Phase Exponential Growth Phase Organisms are adapting to the new conditions, and very little reproduction occurring (low natality)Organisms numbers increase rapidly, as there is an abundance of nutrients / resources, with little competitionHigh natality and low mortalityLittle accumulation of waste products
27Population Growth (cont) Linear Growth PhaseGrowth slows due to decrease in natality, but still high, and an increasing mortality rateChecks on growth are due to more competition, less nutrients and more wasteStarting to approach carrying capacityStart to see environmental resistance
28Population Growth (cont) Plateau PhaseThere is no new growth, due to the environmental resistance and the population reaching carrying capacity.Natality and mortality are equal as there is a limit to the amount of resources supplied by the environment, maximizing how many individuals can be supported.
30Causes of Population Growth Causes of the Exponential PhasePlentiful resource such as food, space or lightLittle or no competition from other inhabitantsFavourable abiotic factors, such as temperature or dissolved oxygen levelsLittle or no predation or disease
31Causes of Population Growth (cont) Causes of the Transitional or Linear Growth PhaseWith an increase in individuals in the population, there is increasing competition for resourcesPredators, attracted by a growing food supply, start to move in to the areaLarge numbers of individuals living together in a limited space, opportunities for diseases to spread within the population increase.
32Causes of Population Growth (cont) Causes of the Plateau PhaseSpace available for growth, such as plants, or shelter is occupied to the maximumLimited food supply, means less available nutrients and organisms tend to have smaller numbers of offspringIncreases in predators and disease increase mortalityTherefore, birth rate plus immigration is balanced with the number of deaths and number of emigrationsCarrying Capacity has been reachedEnvironmental Resistance is observed
33Limiting Factors on Population Growth Density-IndependentA sudden, rapid change in one or more of the physical or chemical components of the environment may occur.This affects the population regardless of size, and affect the overall size of the population or reducing the birth and death rates.Examples are death due to weather, earthquakes, drought.
34Limiting Factors on Population Growth (cont) Density DependentEffect of other members of the population, and of members of other populations, as the density (numbers of organisms in a given area) increases.Examples are predation, disease or intra-species competition. The effects of these factors increase with increasing population numbers.
35Limiting Factors on Population Growth (cont) There are several mechanisms that work with the limiting factorsExtrinsic Regulatory Mechanisms – originate outside the population and include biotic as well as physical factors. For example food supplies, natural enemies, disease, weather.Intrinsic Regulatory Mechanisms – originate in the anatomy, physiology and behaviour. Competition is the main regulating mechanism for large groups.
36Populations as Units of Structure and Function - Statistics
37Populations as Units of Structure and Function - Statistics Random SampleA method to ensure that every individual in a population has an equal chance of being selected
38Group Measuring Techniques Capture – Mark – Release – Recapture (Lincoln Index)Allows for random sampleApproximate count of organisms in an areaAssumes there is no natality, mortality, immigration and emmigrationBanding of birdsTagging of larger organisms
39Group Measuring Techniques (cont) Quadrat Sampling MethodAllows for a simple way to measure population sizeAllows for a random sampleIn areas of differing slope or variation (ie. From terrestrial to aquatic), a line transect can be used
40Using Statistics to Measure Populations MeanThe mathematics of collection, organization, and interpretation of numerical data, especially the analysis of population characteristics by inference from samplingThe average value obtained by dividing the total of a set of values by the number of values
41Using Statistics to Measure Populations MedianModeThe middle value that separates the higher half of a data set from the lower half of the dataThe most frequently occurring data observation
42Using Statistics to Measure Populations Standard DeviationMathematical concept used to summarize the spread of variables around a mean.68% of the values of a normal distribution fall within one standard deviation of the mean (+/-1)
44Using Standard Deviation StepsFind the meanSubtract the mean from all values, and square each differenceAdd up all answers from the above stepPut answer from above into the equation and calculate the SDState the variance by calculating SD +/- mean
45Community Interactions Interactions within ecosystems can be:Neutral – neither organism is affectedOne organism is affectedBoth organisms are affectedExamples are:Symbiosis / MutualismParasitismPredationCompetition
48Greenhouse Effect What is the greenhouse effect? Do we need the greenhouse effect?What is the difference between the greenhouse effect and the enhanced greenhouse effect?
49Greenhouse Gases Carbon dioxide (CO2) Carbon monoxide (CO) Cellular respirationCombustionDecalcificationCarbon monoxide (CO)Incomplete combustionWater vapour (H2O)Occurs naturally, through the water cycle, but product of cellular respiration and combustion
50Greenhouse Gases Nitrogen oxides (NOx) Methane (CH3) Combustion of fossil fuels, refining process of oresMethane (CH3)Naturally occurring, breakdown of organic wasteIncomplete combustionChlorofluorocarbons (CFC’s)Refrigeration / cooling productsBreaks down ozone
51Is the enhanced greenhouse effect leading to Global Warming or Climate Change?
52Is the enhanced greenhouse effect leading to Global Warming or Climate Change?
53Precautionary Principle When an activity raises threats of harm, measures should be taken, even if a cause and effect relationship has not been established scientifically.ExamplesSmoking in BarsSeatbelts
54Evaluating the Precautionary Principle Pros and Cons of implementation in response to Climate Change
55Consequences of Climate Change on Arctic Ecosystems What impacts will climate change have on Arctic Ecosystems?