Ecology Chap 55

Front 1

ecological community

Back 1

all species that live in a certain and interact in a given area; each species has unique interactions with the environment; consists of many species, not just one

Front 2

trophic levels

Back 2

classification system based on how organism obtains energy; i.e. photosynthesizers, herbivores, secondary consumers, tertiary consumers, omnivores, detritivores

Front 3

How do interactions of a predator species affect lower trophic levels? Example.

Back 3

i.e. wolves were extirpated from Yellowstone - elk popluation rapidly increased - elk ate willows and aspens - beavers were almost exterminated - reintroduction of wolves allows aspen, willow, and beaver populations to increase

Front 4

primary producers

Back 4

i.e. photosynthesizers; autotrophs; get energy directly from sun

Front 5

heterotrophs

Back 5

consume, directly or indirectly, molecules (energy) made by primary producers

Front 6

primary consumers/herbivores

Back 6

organisms who eat plants; i.e. termites, grasshoppers, deer, geese

Front 7

secondary consumers/primary carnivores

Back 7

organisms that eat herbivores; i.e. spiders, warblers, wolves

Front 8

tertiary consumers/secondary carnivores

Back 8

organisms that eat secondary consumers; i.e. tuna, falcons, killer whales

Front 9

detritivores

Back 9

aka decomposers; eat dead bodies and waste products (aka detritus) and transform them into free mineral nutrients that are used again by plants; whole ecosystem productivity depends on the decomposition of detritus; i.e. fungi, bacteria, earthworms

Front 10

Are vultures detritivores?

Back 10

No. Vultures are not detritivores because they do not physically decompose waste- they just eat it.

Front 11

omnivores

Back 11

obtain energy from several trophic levels; i.e. humans, opposums, crabs, robins

Front 12

food chain

Back 12

a sequence in which trophic levels obtain energy (i.e. the big shark eats the littler shark, and the littler shark eats the uni-cellular shark, etc.)

Front 13

food chain vs. food web

Back 13

Food chains are interconnected to form food webs; parts of one food chain can overlap with other food chains

Front 14

Biomass

Back 14

weight of living matter; biomass and enegy decrease as they flow from lower to higher levels i.e. a forest has highi biomass in the primary producer level (much energy is stored as wood that is hard for herbivores to digest)

Front 15

Why is the biomass distribution inverted in aquatic systems?

Back 15

High rates of cell divison support a high biomass of herbivores, much more than the primary producers (bacteria and protists).

Front 16

Predation/parasitism

Back 16

one participant is harmed, the other benefits; parasites are ususally smaller than hosts, often feed on the host without killing it

Front 17

Competition

Back 17

two organisms using same resource that is insufficient to supply needs of both; both species are harmed; can restrict a species' habitat, range by reducing populations of a shared prey species

Front 18

Mutualism

Back 18

both species benefit; i.e. plants and Nitrogen-fixing bacteria, termites and trychonympha

Front 19

Commensalism

Back 19

one participant benefits and the other is unaffected; i.e. rhino and cattle egret

Front 20

Ammensalism

Back 20

one participant is harmed, and the other is unaffected; widespread; i.e. herds of mammals trampling plants that smaller animals eat

Front 21

Predator-prey relationships

Back 21

predators are larger and live outside prey's body (vs. parasite); predators typically kill prey, with the exception of herbivores who usually spare the plant's life; predator and prey relationships are directly proportional; if predator population grows too fast, it reduces the prey pop. too fast, and the predator pop. crashes without food; i.e. megapodes who incubate eggs in a dirt mound don't live where there are predators who eat eggs

Front 22

prey survival adaptations

Back 22

i.e. toxic hairs, tough spines, noxious chemicals, camouflage, mimicry

Front 23

batesian mimicry

Back 23

a palatable species mimcs an unpalatable or noxious species; can be maintained if the mimic is less common in the environment than the unpalatable species

Front 24

mullerian mimicry

Back 24

two or more unpalatable or noxious species converge to look alike; all species in the system benefit when an inexperienced predator eats one individual and learns to avoid individuals of all the species

Front 25

microparasites

Back 25

microscopic parasites (duh); i.e. bacteria, viruses; microparasite populations depend upon new hosts becoming infected before the current host dies; populations decrease if more hosts become immune

Front 26

interference competition

Back 26

one species interferes with the activities of another

Front 27

exploitation competition

Back 27

one species reduces the availability of a resource

Front 28

intraspecific competition

Back 28

competition occuring between individuals of the same species; a primary cause of density-dependent birth and death rates

Front 29

interspecific competition

Back 29

occurs between individuals of different species

Front 30

competitive exclusion

Back 30

when a superior competitor prevents another species from using a habitat

Front 31

Are interactions between plants and their pollinators and seed dispersers always mutualistic?

Back 31

No. Seed dispersers can be seed predators and destroy some of the seeds; animals can also cut holes in petals to gain access to nectar without transferring any pollen. Plants can also expoit pollinators through immitation of female insects, so male insects transfer pollen but receive no nectar or offspring reward

Front 32

How do trophic cascades affect multiple ecosystems? Example.

Back 32

i.e. fish predation on dragonfly larvae in one habitat = dragonfly larvae are more abundant in ponds without fish - insects dragonfly prey on are less common - flowers in fish-free ponds were rarely visited by insect pollinators

i.e. beavers

Front 33

ecosystem engineers

Back 33

organisms that build structures that alter habitats, species composition, vegetation; i.e. beavers

Front 34

keystone species

Back 34

a species that exerts influence out of proportion with its abundance; can influence species richness and the flow of energy and materials; i.e. sea stars control mussel popluations so other species have space to live; don't have to be predators, necessarily

Front 35

disturbance

Back 35

an event that changes the survival rate of one or more species; i.e. windstorm that knocks down a tree makes space and resources for other species

Front 36

succession

Back 36

change in community composition after a disturbance

Front 37

primary succession

Back 37

begins on sites that lack living organisms

Front 38

secondary succession

Back 38

begins on sites where some organisms have survived

Front 39

facilitation

Back 39

species that colonize first create environmental conditions that allow other species to follow

Front 40

intermediate disturbance hypothesis

Back 40

communities with intermediate levels of disturbance tend to have more species than those with high or low levels of disturbance; only species with dispersal capabilities and high reproductive rates can survive in areas with high disturbance; competition reduces species richness in low disturbance levels

Front 41

species richness

Back 41

number of species living in a community; correlates with ecosystem productivity; interspecific competition can be more intense when productivity is high => competitive exclusion; can also enhance productivity because more species are using all possible resources; species-rich ecosystems are more stable over time