lec 14- other types of interactions

Question 1

what are trophic level and cascade?

Answer 1

trophic level- position an organism occupies in a food web
trophic cascade- indirect effects or interactions that can control an ecosystem

Question 2

what is commensalism?

Answer 2

one species is benefiting while the other is neutral (ex. lichen on a tree, scavengers and predators killing prey)

Question 3

what is mutualism ?

Answer 3

both species benefit from one another (nitrogen fixating bacteria which gain sugar and give fixed nitrogen)

Question 4

types of mutualism?

Answer 4

trophic: ways organisms gain energy and nutrients (nitrogen fixating bacteria/ fungi)
defensive: one species receives food/shelter in return for defense (clown fish gives nutrients and anemone gives defensive shelter)
dispersive: one species receives food in return for dispersal (pollinators gain food and disperse pollen, birds disperse seeds after getting food)

Question 5

describe positive indirect effects:

Answer 5

wolves in Yellowstone decrease elk numbers resulting in increase of struggling plants that needed recovery