Ecology Exam 2

invasive species

some species cause significant economic, ecological, and health costs

non native, exotic, alien, or invasive species

all refer to species that are currently occurring outside of their natural range usually because of human transport

trophic cascades

occur when predators limit the density and/or behavior of their prey, thereby enhancing the survival of the next lower trophic level

daphnia

small crustaceans, typically filter feeders that ingests protists, bacteria, and various sorts of organic detritus

ecosystem services

the benefits the natural environment provides to humans

weedy species

adaptable, small, fast reproducing, which appear to be good reservoirs for disease

diffusion dispersal

dispersal along an expanding front

jump dispersal

rare long distance movement resulting in colonization (founders events)

stratified dispersal

a combination of diffusion and jump dispersal

increase of non natives with time

1. increased sampling effort with time

2. population growth of earlier introductions

3. introduction of additional species

propagule pressure

1. number of individuals introduced in a single event

2. number of introductions

Allee effect

populations individual growth rate increases as population size increases

lag times for invasion

1. demographic growth

2. undergoing section in the new range

3. awaiting infusion of new genetic material

invasibility diversity hypothesis

communities with high diversity should resist invasions (fewer niches, fewer resources for new species)

genetically modified organism (GMO)

organisms who’s DNA has been altered, often with the addition of a gene from a distant species to produce a desired trait

herbicide tolerance (HT)

most common inserted trait, makes the crop resistant to particular herbicide

insect resistance (Bt)

second most common trait, gene for Bt toxin is toxic to chewing insects

increased nutrients

researchers have explored many different methods of increasing production of vitamins and other nutrients in plants