ENV100H1 Lecture Notes - Lecture 14: Metapopulation, Ecological Niche, Keystone Species
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Problems de ning a species molecular techniques not always straightforward. What is species diversity? richness= number of species (mostly!!) evenness= relative abundance of species (a lot of work to calculate) Most species are rare (hard to detect) usually just sample for dominant species. Shelford"s law of tolerance (fundamental niche) growth is narrower than survival reproduction is even more sensitive. Models to explain diversity equilibrium models niche slow competitive displacement (random variation obscures directional change) Non-equilibrium models sometimes species won"t displace other species as e ectively slow e. g. tropical forest neutral theory (null model- patterns of diversity: speciation, death, random, replacement) Uctuating environment (temporal variability) spatial patchiness, density-independent uctuations metapopulation dynamics at the landscape level (source-sink populations) Species-area relationship latitudinal gradient productivity gradient intermediate disturbance hypothesis. Fish diversity in lakes larger ecosystem= more species big implications designing parks etc. Latitudinal gradients in diversity species richness decreases with increase latitude. Latitudinal gradient in bird richness highest species richness at 0 degrees latitudinal.
