BIOL 4253 : Exam3 Chp 16
Document Summary
Species abundance: there are regularities in the relative abundance of species in communities that hold irregardless of the ecosystem, preston developed concept of distribution of commonness and rarity. Generally we are trying to find a pattern. Frank preston was interested in why things are common or rare. Lognormal distribution: preston graphed abundance of species in collections as frequency distributions he collected moths, he was an industrialist so he paid for this himself, lognormal distributions, bell-shaped curves. In most lognormal distributions, only portion of bell- shaped curve is apparent: sample size affects the veil line , significant effort to capture rare species. Counted each species and plotted the number of species that had each abundance. The species that were originally very common were still very common. Shows that as your collect more moths you get a better idea of the curve. You can describe this data using a normal curve (bell shaped)
