Fragementation not only effects the number and spreading of species, it also has influence on the genetic composition of populations. Under normal conditions populations have sufficient genetic variation. Individuals within a population are genetically different. The rate of homozygoty is generally low. The latter may cause deficienties such as high mortality and a low rate of reproduction.
Fragmentation causes local extinction of species within local populations.
Therefore measurements to be taken in order to maintain or regain species in a fragmentated landscape or region should deminish the chances for extinction or increase the chances for recolonization. Such measurement are the improvement and enlargement of the habitats of local populations and the making of connections between local populations. Environmental Heterogeneity and diversity Two or more divergent phenotypes in an environment may be favoured simultaneously by diversifying selection. This is called environmental heterogeneity . Species cope with environmental heterogeneity in diverse ways.