ENV234H1 Lecture Notes - Lecture 13: Seaweed, Lake Superior, Snow Goose
Document Summary
Lecture 13 (lecture 12 material cont"d) terrestrial biomes: Last class: temperature driving production and what types of organisms are in different places. Shifts in ranges of other organisms (spiders, mollusks etc: changes in latitude and altitude. Graphs show shifts of species: altitudinal shifts (bottom right graph): Expected shift from temperature (straight linear line) All the points are clumped at the bottom. Means that it is not necessarily temperature that is driving species shift. Shifts have been observed in these species but graph shows that isn"t temperature driving shift in these animals. Many other environmental variables why organisms don"t shift: Dispersal: maybe not enough time for them to move, haven"t gotten there yet. Biotic interactions: once they get to a site, there might be negative interactions. Competition, predators: so even if conditions are right, they may not be able to live there. Organisms can also extend their ranges seasonally. Spring coming earlier and fall coming later: = longer growing species.
