Internal. The ultimate sources of variation, the source of new heritable characteristics in populations and species, are due to mutation and recombination in chromosomes, genes, DNA.
Zone VE is the flood insurance rate zone that corresponds to coastal areas that have additional hazards associated with storm waves. Mandatory flood insurance requirements apply. Zone X and Zone X-500 are flood insurance rate zones that are outside the flood plain or with average flood depths of less than 1 foot.
1 For more information on flood zones, see FEMA's FloodSmart web page. 2  Zone AE are areas that have a 1% probability of flooding every year (also known as the 100-year floodplain), and where predicted flood water elevations above mean sea level have been established. Shaded Zone X are areas that have a 0.2% probability of flooding every year (also known as the 500-year floodplain). 2  Properties in Shaded Zone X are considered to be at moderate risk of flooding under the National Flood Insurance Program.