Ecosystem Structure - Earth and environmental sciencecherylannhayes.weebly.com/uploads/8/6/8/9/86894960/ch_3-5_notes… · Ecosystem: community of different species interacting with

D. Shell, 2013 SMHS

Ecosystem Structure I Biological populations and communities - Levels of Organization Studied in Ecology (smallest biggest)

Organism/Species: organisms of same species have same appearance, behavior, chemistry, genetic makeup, produce fertile offspring

Population: group of interacting individuals of the same species that occupy a specific area at the same time

Community: populations of all the different species occupying a particular place

Ecosystem: community of different species interacting with one another and with nonliving environment (biotic + abiotic)

Biosphere: (aka - Ecosphere) all ecosystems together; portion of the earth in which biotic organisms exist and interact

Characteristics of Living Things 1. Organization (have structure)

a. have one or more cells b. cells have DNA

2. Reproduce - continuation of species 3. Growth - increase living material & new structure 4. Respond to stimuli 5. Homeostasis - organisms must maintain a fairly consistent internal environment to maintain life. Ex. Keep proper internal

temperature Ex. Maintain correct water, mineral balance 6. Create energy- either digest external food or create food thru photosynthesis & / or chemosynthesis 7. Adapt - change to meet a changing environment any structure, behavior, or internal process that helps an organism survive better

= adaptation; adaptations are inherited from previous generations. Over time, accumulated adaptation cause the species to change = evolution

II ecological niches A Habitat: where an organism actually lives B Niche: what the organism’s job is in that area -

1. range of conditions & resources within which the organism can live (real niche never as big as it could be due to competition – realized niche is the actual niche)

2. No two species can occupy the same niche at the same time. C Generalist vs Specialist species

1. Generalist – can easily adapt to environmental changes; eat a variety of foods; live in many places; 2. Specialist – have a small range; do not adapt well; eat

only a few foods; specialized reproduction III interactions among species

A 3 Basic Types of Species Interaction 1. Interspecific Competition - competition between

members of two or more different species for food, space, or any other limiting resource

2. Intraspecific Competition – competition between members of the same species for food, space, mates or limiting resources

3. Competitive Exclusion - similar species cannot occupy the same niche indefinitely, one species eliminates the other through competition for limited resources

D. Shell, 2013 SMHS

The Green Anole is from Florida. (green niche) When the brown Anole was introduced from Cuba it first overlapped the niche of the

Green Anole. But according to Competitive Exclusion, the larger Brown Anole overtook part of the Green’s niche.

B How do species reduce competition?

1. Resource Partitioning - dividing up resources by using at different times, different ways, different places. ex. Owls & hawks -similar prey but hawks feed/day and owls feed/night; Lions & leopards -similar prey, but lions/larger prey & leopards/smaller prey

C Animal Relationships: 1. Predation one species (predator) feed directly on living organism of another species by pursuit or

ambush (removes weakest of prey from population). Since predators must assess prey during pursuit or stalking, their brains are usually larger than prey animals a Ways to Avoid Predators:

(i) Camouflage (ii) Chemical Warfare (iii) Travel in schools or herds (iv) Warning Coloration (v) Poison (vi) Deceptive looks & behaviors (vii) Shells, speed, flight, smell (viii) mimicry

2. Symbiosis - relationship in which species live together in an intimate association a Commensalisms one species benefits & host doesn’t care

b Mutualism - both species benefit (i) ex. nutritional mutualism (ii) lichens (fungus + blue-green cyanbacteria) (iii) legume root nodules (N2-fixing bacteria+ plant root)

3. Parasitism - parasite benefits & host harmed a similar to predation but parasite is usually smaller than host, gradually weakens host, &

rarely kills host

D Indicator Species - sensitive species that provide early warning of ecosystem problems (their #’s go down before other species)

IV keystone species – species who play a major role in the ecosystem (Ex: pollinators, top predators, etc) V species diversity and edge effects – different types of organisms in the same area at the same time.

A Edge Effect – changes to an environment along the edge of an area VI major terrestrial and aquatic biomes

A 3 major types of Ecosystems 1. Terrestrial (land)

a are subdivided into biomes (large regions characterized by distinct climate & specific life form, especially vegetation)

b Climate—long term weather patterns (determines life forms in biomes) 2. Aquatic (salt water & fresh) 3. Ecotone (transition area between terrestrial & aquatic)

a swamps, edge of forest & field (some land animals, some water too, some unique)

Lamprey + fish

Orchid + tree

Clownfish + sea anemone

D. Shell, 2013 SMHS

B Major components of Ecosystems 1. Abiotic nonliving components (water, air, nutrients, solar energy)

a Zone of tolerance: min. & max range of environmental factors that organism can survive in (optimal range can be small) (i) Most organisms are least tolerant during juvenile or reproductive stages (ii) Edges of graph – organisms that are strongest / most able to adapt to changes.

b Limiting factor: single factor that can limit or prevent growth of a population (too much or too little) (i) Examples:

2. Biotic living components (plants, animals, microbes) 3. Biodiversity: different life forms 4. Metabolism: complete set of chemical reactions that carries out specific roles in cells & organisms. Converts sun

energy to chemical energy **See Biome Notes (separate paper) **

Energy Flow One way flow of energy starting from sun plants consumers decomposers heat (2

nd law thermodynamics)

Nutrients cycle between living and nonliving world by means of energy provided ultimately by the sun. I Photosynthesis and cellular respiration

A Producers (autotrophs): make own food 1. Photosynthesis: sun energy + CO2 +H2O C6H12O6 + O2 2. Chemosynthesis

B Consumers (heterotrophs) obtain food by eating others 1. Respiration: C6H12O6 + O2 CO2 +H2O + ATP energy

II food webs and trophic levels;

A Organization of organisms / Energy flow 1. Herbivores (1

o consumers) feed directly on producers

2. Carnivores (2o, 3

o consumers) feed on other consumers

3. Omnivores eat both plants/animals 4. Scavengers (ex. vultures, flies, crows, hyenas) feed on

dead organisms 5. Detritivores (ex. worms, ants, wood beetles) feed on

detritus (dead fragments and wastes of living things) 6. Decomposers (fungus & bacteria) break organic dust into

nutrients to enter cycles B Trophic Levels: levels of a food chain (simple chain of consumption)

C Food Web – shows multiple food chains

1. Typically organisms do not consume only one type of organism 2. Must include arrows – pointing in the direction of energy flow

III ecological pyramids

A Show trophic levels by…. 1. By numbers (# of organisms at each level) 2. Biomass (kg of biomass per level) 3. Energy (kJ or calories per level)

B Amounts tend to decrease by 5-20% at each level change (use 10% as a general rule)