Presentation is loading. Please wait.

Presentation is loading. Please wait.

I. Ecology of Ecosystems and Communities

Similar presentations

Presentation on theme: "I. Ecology of Ecosystems and Communities"— Presentation transcript:

1 I. Ecology of Ecosystems and Communities

2 A. Interdependence of Ecosystems
Ecosystems depend on each other for survival (no defined boundaries) Depend on abiotic factors of other ecosystems (temp., wind, sunlight,etc.) Ex: rainforests produce lots of oxygen, wind can carry to other areas to support more consumers.

3 The size of an ecosystem can vary
The size of an ecosystem can vary. It may be a whole forest or a small pond. Ecosystems are often separated by geographical barriers, like deserts, mountains, or oceans, or are isolated such as lakes or rivers. These borders are never rigid, though, so ecosystems tend to blend into each other. As a result, the whole earth can be seen as a single ecosystem, or an individual lake can be divided into several ecosystems, depending on the scale used.

4 B. Energy Flow in Ecosystems
Energy cannot be created or destroyed, but can be transferred to other forms (light energy to heat, electrical, or chemical energy). Most energy in a system is given off as heat (metabolism). Flow of energy: a) light is the initial source for whole ecosystem b) autotrophs produce organic matter with this energy through photosynthesis c) heterotrophs consume macromolecules organic matter through other organisms

5 Types of heterotrophs:
i) consumers feed on other living things -primary (herbivores) -secondary (carnivore) -tertiary (secondary carnivore) ii) detritivores feed on dead organic matter by ingesting it (earthworms) iii) saprotrophs secrete enzymes and ingest broken down products (certain mushrooms) note: detritivores and saprotrophs are not considered to be part of the energy food chain, but are involved in recycling nutrients for an ecosystem

6 Examples of Food Chains
Label Producer Primary consumer Secondary consumer Tertiary consumer Quaternary consumer Trophic Level 1 2 3 4 5 Aquatic Example Elodea (aquatic plant) Freshwater snail Leech Stickleback fish pike Terrestrial Example Carrot Plant Carrot Fly Fly Catcher Bird Sparrow hawk Goshawk Passion-flower Heliconius butterfly Tegu lizard Jaguar

7 Energy Flow Diagrams a) Food webs (at least 10 organisms and 4 trophic levels) i) no more than 5 levels supported ii) 10-20% efficiency between levels, rest lost as heat through cell respiration, metabolism, not assimilated, waste. b) Energy pyramids show relative amount of energy lost at each trophic level (bottom level shows GP of ecosystem) Gross Production= Net Production + Cellular Respiration (10% energy transferred at each level) GP=total amount of organic matter produced by plants -NP=amt. left after cellular respiration -GP represents 1st trophic level measured in KJ m-2year-1 100kJ 1000kJ Gross Production=10000kJ

8 Example: Field in Michigan
Net Production = 20.79 x 103 kJ m-2 year-1 Plant Respiration= 3.68 x 103 kJ m-2 year-1 GP= x 103 kJ m-2 year-1 (GP=NP + PR)

9 Biomass=organic matter
-Loss of biomass accompanies loss of energy because organic matter consumed has mass! -energy content per gram of food stays relatively constant -total number of biomass available in higher trophic levels is small; low numbers of organisms at high trophic levels-not enough biomass to support Assignment of Trophic Levels: Sometimes difficult due to variety in diet of organisms, classified by main food source Examples: Euglena-producer and consumer Oyster-consumer, detritivore

10 Nutrient Flow in Ecosystems
-energy can leave or enter an ecosystem, nutrients must be recycled (C, P, N2) -done through biogeochemical cycles a) Carbon Cycle b) Nitrogen Cycle c) Phosphorus Cycle

11 Components of the Nitrogen Cycle
Bacteria (chemoautotrophs) Nitrogen Fixation (converts atmospheric nitrogen-N2 to ammonia-NH3) -Azotobacter (soil) -Rhizobium (found in root nodules of legumes) Nitrification (changes NH3 to NO2- (nitrite) and then to NO3- (nitrate)) -Nitrosomonas (nitrification I to nitrite) -Nitrobacter (nitrification II to nitrate) Denitrification (changes NO3- back to atmospheric nitrogen-N2) -Pseudomonas denitrificans (anaerobic conditions to use nitrate as an electron acceptor instead of oxygen) Farmers/Gardeners -nitrogen fertilizers -plowing and digging -crop rotation (legumes increase nitrogen content)

12 Ecology of Species Distribution of Plants
-ranges of places it inhabits depending on abiotic factors (soil pH, temp., water, light, salinity, etc.) -Avicennia germinans is a Mexican swamptree that grows where soil is anaerobic and pH is neutral; thrives where most plants would not survive

13 Distribution of Animals 1) Temperature (especially ectothermic)
2) Water (required amount varies) 3) Breeding sites (ex:mosquitos in stagnant water) 4) Food supply (type of food needed must be available) 5) Territory (defended for feeding and breeding) The Niche Concept 1) habitat, nutrition, relationships with other organisms 2) Competitive Exclusion Principle

14 Ecological Succession
-changes to an ecosystem caused by interactions between living organisms and abiotic environment -some species die, others join until stable=climax community (about 200 years) -usually due to environmental catastrophe (volcanic eruption, forest fire, grass fire, etc.) -glaciers are a good example (organic matter in soil increases, soil becomes deeper, increase in amt. of water retained, excess drainage, soil erosion, mineral recycling increases)

15 III. Population Ecology
Studying Population Size 1.) natality, mortality, immigration, emigration 2.) Population Curve (exponential, transitional, and plateau phases; carrying capacity 3.) Measurement of Population Size a) random sampling- every individual has an equal chance of being selected

16 Types of Random Sampling
i) Quadrats 1 sq. meter good for organisms that don’t move count species in quadrats all over, get mean # plants per quadrat, estimate total area formula: population size = mean #per quadrat x total area area of each quadrat Example: data= 6,8,7,4,3,2 total area = 250 sq.meters 5(250)/1=1250 plants

17 ii) Capture-mark-release-recapture method
Good for animals that move around Trap lots of animals in area, mark or tag carefully, release, recapture Count how many marked/unmarked Use Lincoln Index to estimate population size n1= total # organisms first caught and marked n2= total # caught in second sample n3= # marked in second sample total population size = n1 x n2 n3

18 Using Statistics in Ecological Research
1.) Mean=sum of all values divided by the total number of values 2.) Standard Deviation =spread of values around the mean (measures how closely values are clustered toward the mean value) Normal Distribution Curve (Grades)

19 68% of data usually falls within +/- 1
68% of data usually falls within +/ standard deviation of the mean value 95% of data falls within +/ standard deviations of the mean value

20 3.) The T-Test -Used to find if there is a significant difference between the mean values of two populations a) The null hypothesis (Ho)=states that there is NO difference between the two populations and the difference in mean values is due to errors in sampling b) Probability (p) = If the probability that a null hypothesis is correct is low (less than .05 or 5%), the null hypothesis is rejected and there is a significant difference between the two populations c) Degrees of freedom =a method to estimate variability in a sample (for a t-test, df=(n1+n2)-2

21 Methods to analyze t-test results:
a) Table of Critical Values (handout)- used to decide whether there is a significant difference between two populations. If the calculated t-value is less than the critical value found on the chart, there is no significant difference between the mean values and the null hypothesis is accepted. If calculated t-value is greater than the critical value, the difference is significant and the null is rejected. b) Analysis of p-value- computer program will tell you a p-value so you can decide if it is greater or less than .05 and whether or not the difference is significant.

22 total # of organisms = N D= N(N-1)
4.) Simpson Diversity Index –measures “species richness” in an ecosystem through random sampling a.) instead of focusing on one particular organism, all organisms are accounted for b.) used to assess areas for wildlife conservation purposes (value can be from 1.0 to anything, but is most valuable when compared to other calculated indexes c.) Formula: total # of organisms = N D= N(N-1) number of species = ∑ n(n-1) diversity index = D Ex: Collect 3 species with 40, 25, and 15 individuals D= (80 x 79)/(40 x 39) + (25 x 24) + (15 x 14) = 6320/2370=2.67

23 IV. Evolution -process of cumulative change in heritable characteristics of a population Charles Darwin’s Observations and Deductions A) Populations of organisms increase exponentially but stay the same overall Environment cannot support so much, so organisms will eventually struggle for survival B) Members of a species have variation, some of which are favorable for their environment Better adapted individuals tend to survive (natural selection) C) Variations and traits are hereditary As generations follow, characteristics change and a species can evolve

24 Sexual Reproduction and Evolution
Meiosis-(crossing over, two sources of genes, new combinations of alleles) Fertilization allows variation (change of traits over time so species can survive Asexual reproduction provides less capacity for evolution (but can produce some mutations for variation)

25 Environmental Change and Evolution a.) antibiotic resistance
1) gene given to bacterium gives variation so some are resistant and some are not 2) Natural selection favors resistant bacteria when antibiotics administered 3) Non-resistant bacteria killed 4) Resistant bacteria reproduce and spread (mostly resistant) 5) Doctors change to different antibiotic, same things happen, multiple resistance evolves

26 B.) Metal Tolerance in Plants
1.) Waste from mining, plants don’t grow well (copper pollution) 2.) Some plants do grow 3.) Growing plants are tested for copper tolerance and compared to plants in a non-polluted area 4.) Plants in the polluted area more copper tolerant, offspring more copper tolerant than n non- polluted area 5.) Pollen carrying copper tolerance genes can be carried by wind to other areas

27 Classification 1.) Taxonomy-classification into groups
valuable for: a) species identification (file already exists) b) predictive value (same groups) c) evolutionary links (common ancestors) 1.) Taxonomy-classification into groups Human Blue Whale Sequoia Plant Kingdom Animalia Animalia Plantae Phylum Chordata Chordata Coniferophyta Class Mammaila Mammaila Pinopsida Order Primates Cetacea Pinales Family Homonidae Balaenopteridae Taxodiaceae Genus Homo Balenoptera Sequoia Species Homo sapiens Balenoptera Sequoia musculus sempervirens

28 2.) Binomial System-international genus (group of similar species) and species names (Ex: Homo sapiens) Rules: for naming species a.) first name (genus name) is capitalized b.) second name is lower case c.) both names underlined if handwritten, italics if printed 3.) Generally 5 Kingdoms: Prokaryotes (bacteria), Protista (algae, amoeba, paramecia), Fungi (molds and yeasts), Plantae, Animalia 4.) Dichotomous Keys

29 VI. Conservation of Biodiversity
Reasons for conservation 1) Economic (medicines, new crops, etc.) 2) Ecological (species interdependency, changes are damaging, etc.) 3) Ethical (right to life, cultural importance) 4) Aesthetic (looks nice, inspiring)

30 Monitoring Environmental Change
Extinction of Species Examples: passenger pigeon, dodo bird, Carolina parakeet, Sexton Mountain mariposa lily Monitoring Environmental Change 1) Living organisms can act as “indicator species” Examples: -lichens (tolerance of SO2) -stonefly, mayfly, damselfly larvae require unpolluted, well-oxygenated water -chironomid midge larvae, rat-tailed maggot larvae, tubifex worms show low oxygen levels (too much organic matter) 2) Abiotic factors (can be measured directly)

31 Nature Reserves Managed through… Restoration of degraded areas
Elimination of aggressive alien species Supplementary feeding and clearing of vegetation if necessary Control of exploitation of animals and vegetation by humans

32 In situ conservation-conserving a species in its own habitat
Good if… Species remain adapted to habitat Greater genetic diversity Natural behavior patterns Interaction of species Not so good if … Too few of species, unsafe in wildlife Destruction of natural habitat could negatively affect species

33 Ex situ conservation- species are conserved outside of their environment
captive breeding-animals caught and moved to a zoo, returned to wildlife when numbers are considered high enough Botanical gardens Seed banks (endangered species can be kept in cold storage for up to 100yrs)

34 What is being done to control this problem?
Conservation of Fish Overexploitation of fish can… Cause fish to fail in spawning Cause fish to become extinct Cause species dependent on fish to decrease in population What is being done to control this problem? International measures (difficult to enforce): Monitoring of populations, reproduction rates Quotas for catches with low population stocks Moratoria for endangered species Minimum net sizes Bans of drift nets

35 International Organizations for Conservation
WWF-World Wildlife Fund monitors endangered species, political lobbying, establishing nature reserves, 10,000 projects in conservation CITES-Convention on International Trade in Endangered Species 100 member states, regulates trade in threatened species (Appendix 1=banning of trade, Appendix 2= monitoring of trade with licensing) reviewed every 2yrs

36 Human Impact Local Impacts-(Introduction of alien species)
Rats in New Zealand Sea Lampreys in Great Lakes Rats/Mongoose in Hawaii Global Impacts A.) Greenhouse Effect Natural Process that is being compounded by humans Greenhouse gases-CO2, CH4, CFCs, H2O, SO2 Effects include global warming, rising sea levels, etc. Sources since 1880 have recorded increased levels of atmospheric CO2 (less photosynthesis from deforestation, increased amounts of fossil fuels)

37 B.) Ozone Depletion O3 absorbs short wave radiation (UV), reduces UV light to earth’s surface UV light -damages DNA, increases mutation rates -increases skin cancer, cataracts, sunburn -reduces photosynthesis rates in plants/algae Caused by CFCs (refrigerants, aerosol, plastics) -Chlorine is bad! UV breaks CFCs and Cl comes out to catalyze the reaction breaking O3 into O2 and O (hundreds of thousands of ozone molecules can be broken up by a single Cl atom) CFCs have been reduced-by 2010, there should be a leveling off of ozone

38 C.) Acid Rain CO2 dissolves in H2O in clouds to make carbonic acid (weak acid) SO2, NO cmpds have more drastic effect (ph=about 3) and are caused by human activities (vehicles, power stations, industry) Lakes rich in limestone can be buffered (CaCO3) Acidification of soil where K+, Ca2+ and Mg2+ are leached out making soil less fertile Trees have premature leaf fall Aluminum becomes soluble in water and combines with acid anion. This compound runs into lakes, streams and is toxic to fish

39 D.) Eutrophication (increased level of mineral nutrients in water)
Happens when raw sewage goes into rivers (bathing, drinking water pathogens become a problem as well) Nitrate Sewage (Organic Matter) Bacteria (consume and Proliferate) More Bacteria (less O2, inc. In BOD) Some Fish Killed Nitrifying bacteria Bacteria Digest organic Matter to make NH3, PO4-3 Release of O2 Reoxygenated H2O Primary Consumers Feed on algae Algal Bloom (Photosynthetic Bacteria and algae Absorb nutrients) Eutrophication Recovery Of River

40 Nitrate Fertilizer in rivers can also cause eutrophication
-algal blooms-too much algae so some die and sink to the bottom -bacteria decompose dead algae, increase BOD and deoxygenate water -low oxygen levels kill fish E.) Biological Fuels Biomass can be used for fuel (wood, crop residues, dried manure, ethanol and methane)

41 Generation of Methane (renewable and non-polluting)
Need methanogenic bacteria (anaerobic) to produce methane from CO2, H2, CH3COOH or a bioreactor that mimics this process (handout) Reactions: CO2 + 4H2 CH4 + 2H2O CH3COOH CH4 + CO2 First groups of bacteria convert organic matter into acids and alcohol Second groups of bacteria convert organic acids and alcohol to CO2, H2, and CH3COOH Third groups of bacteria are methanogens (Methanobacterium and Methanococcus) Leftovers are used for fertilizer

Download ppt "I. Ecology of Ecosystems and Communities"

Similar presentations

Ads by Google