Lecture 7: Community & Ecosystem Ecology

what is ecology?

the study of the relationship of organisms to the environment and to other organisms

what are the 5 trophic levels?

primary producers, primary consumers, secondary consumers, tertiary consumers, apex predator

what are primary producers? what is another name for them?

organisms that make their own food through photosynthesis (plants) or using chemicals (some bacteria). another name: autotrophs

what does autotroph mean?

self feeding (plants)

what does heterotroph mean?

feeds off of others (primary/secondary/tertiary consumers, apex predator)

what are primary consumers? what word describes their diets?

organisms that eat the primary producers (plants). they are herbivores

what are secondary/tertiary consumers?

secondary consumers: eat the primary consumers (carnivores, heterotroph)

tertiary consumers: eat the secondary consumers (carnivores, heterotroph)

what are quaternary consumers? what is another name for them?

apex predators: predators at the top of the food chain with no natural predators

eg. lions, bears, tigers, crocodiles

what is the 10% rule?

energy flow is inefficient from one tropic level to another. when energy is passed in an ecosystem from one trophic level to the next, only 10% of the energy will be passed on. 90% of that energy will be lost as heat, etc. to the environment

why are shorter food chains more efficient?

in shorter food chains, there are less trophic levels for the energy to transfer through, so less energy is lost

why are food webs a more realistic representation of the food chain?

there are many complex interactions between the organisms of an ecosystem

what are 3 main community/ecosyetem interactions?

• predation: where one individual is eating another individual

• competition: 2 individuals are fighting for the same resource

• symbiosis: close interaction between 2-3 different organisms that live in close association with one another

name 3 prey defenses

• aposematic coloration: bright colors that warn predators that an organism is poisonous (poison dart frog, monarch caterpillar)

• batesian mimicry: when a non-poisonous animal mimics the appearance of an animal that is poisonous

• camouflage: an organism blends into its environment

what are the 2 kinds of competition?

• intraspecific: competition within the same species (fighting for a mate)

• interspecific: competition between 2 different species (fighting for food)

what does the competitive exclusion principle state?

2 species competing for the same resource in the same location cannot coexist

• if 2 organisms are fighting for the same resource, an organism might find a different resource or a different location

what is resource partitioning?

when 2 species use the same resource differently, so that they are not fighting for the same resource in the same location.

eg: brown creeper and white breasted nuthatch - white breasted nuthatch always walks down a tree to look for food, while the brown creeper always walks up a tree to look for food

what is symbiosis? what are the 3 types of symbiosis?

any relationship where 2 or more species live closely together.

3 types: mutualism, commensalism, parasitism

what is mutualism? give examples

a +/+ association, where all species involved are benefitting from the association

eg. oxpecker and impala, cleaner shrimp and eel, bees and flowers

what is commensalism? give examples

a +/0 association, where one species benefits, and the other species is not affected

eg. shark and remora, whale and barnacle

what is parasitism? give examples

a + / - association where one individual benefits and one individual is harmed

eg. ant and roundworms, hornworm and wasp

what is a keystone species?

a species that when present keeps biodiversity high in that area. the extinction of a keystone species would consequently lead to the extinction of many other species

eg. wolf, sea star, otter, prairie dogs

eg. Thomas Payne’s experiment with sea stars in the Pacific Northwest: sea stars retain biodiversity. when they are taken away, mussels outcompete all other species

what are biomes? name examples

large scale environments that are distinguished by characteristic temps and precipitation levels, which lead to different animals and plants

• forests

• grasslands

• deserts

• tundra

• aquatic

what factors most impact terrestrial biomes? what affects these factors?

precipitation and temperature (impacted by latitude and longitude)

describe the 3 forest biomes

forests are dominated by trees and contain a lot of the world’s biodiversity

3 types:

• tropical: warm and high precipitation. at equatorial region. most biodiverse terrestrial biome. temp and sunlight are stable with high annual rainfall, so they have year-round plant growth

• temperate: middle temperature, 4 seasons. lower annual temp than tropical rainforests. distinct growing seasons rather than year-round growth

• boreal: high latitude, cold and dry, most precipitation in form of snow. cold, dry winters with short, cool, wet summers. pines, spruce, fir trees.

describe the 2 types of grassland biomes

grasslands are dominated by grass with a warm, dry climate

• savannas (tropical grasslands): scattered trees, hot and tropical, annual rainfall higher than temperate grasslands. extremely dry seasons where fire is common and helps the biome survive

• temperate grasslands (prairie or steppe): no trees because they receive very little precipitation

name the 4 kinds of desert biomes

characterized by dry areas with less than 20 inches of annual rainfall, low biodiversity, animals and plants with adaptations to survive the lack of rain

4 types:

• subtropical

• semiarid

• coastal

• cold

describe the 2 kinds of tundra biomes

characterized by simple, low-lying vegetation with no trees. lowest temp of any biome and low annual precipitation. short summer = short growing season. plants and animals must be adapted to extreme conditions. low biodiversity

2 types:

• arctic: high latitudes close to the arctic

• alpine: high elevations in mountains

describe the 2 kinds of aquatic biomes

• freshwater: inland bodies of water surrounded by land with a salt content of less than 1%. eg. lakes and ponds, river and streams, wetlands

• marine: often open area with higher salt content. eg. ocean, coral reefs, estuaries, mangrove forests

describe rivers and streams

• bodies of freshwater flowing in one direction

• start at headwaters and travel great distances, often ending in the ocean

• provide habitat and food for many aquatic/terrestrial species

describe lakes and ponds

• landlocked bodies of freshwater

• ponds are usually smaller and more shallow

• provide habitat and food for many aquatic and terrestrial species

describe wetlands

• places in which the land is covered by water permanently or seasonally

• often recognized by the distinct plants found there

• high biodiversity and critical habitat for many species

• important for cleaning water, shoreline and storm protection, storing carbon from the atmosphere and food security

what are mangrove forests?

a type of wetland

• made up of salt tolerant trees along coastlines

• high biodiversity

• estimated that the world has already lost over ½ of mangrove forests

• breeding ground for many fish and other marine organisms

• protect coastal areas from extreme weather, such as hurricanes and tsunamis