BIOL 203 Lecture Notes - Lecture 18: Canine Tooth, Competitive Exclusion Principle, Niche Differentiation
Document Summary
Allee effect: per capita growth rate declines as population size decreases: different from typical density dependent growth, ex. survival of bighorn sheep. At low population sizes, survival in face of mountain lion predators increases as population size increases: ex. Have to travel further to nd mates - risky business. Also spend more time looking out for predators and less time foraging. Classic experiment by ag tansley: common garden experiment, calcareous soil vs acid soil and two different species of plants. When alone, the plants seemed to grow better in the soils, but when grown together, the growth is depresses: shows that competition is occurring. Testing for competition through removal experiments: desert granivorous rodents - kangaroo rats and pocket mice, put fencing around some plots to try to control rodent access. Some plots had holes for all granivores (large and small) Some other plots which only allowed for small ones to enter.
