ENV221H1 Lecture Notes - Lecture 17: Species Richness
Document Summary
Variety of different organisms and their genes living in a given area. High level of genetic diversity is desirable: more likely to be adaptable to changes in environmental conditions, more likely to survive, have enhanced fecundity, increased resistance to diseases. Conversely, small populations with low genetic diversity are at risk of inbreeding and decreased adaptability to environmental changes deleterious alleles/traits may be expressed through inbreeding: small populations with closely related individuals is bad. Number of different kind so species within the system. Estimates of total species richness on earth ranges between 3-100 million: with 90% living in the tropics, particularly in rainforests.
