Abstract: Inbreeding may reduce population fitness through the expression of recessive and dele-terious alleles in homozygous form. Small populations are more vulnerable for inbreeding depre-ssion, but their responses to the depression may not be observed due to the genetic load purged in studied species, benign environment investigated, differences in studied traits, different deve-lopment stages of studied species, and different family lines, populations, and individuals used. All of these imply that the levels of inbreeding depression are affected ecologically and genetically. The genetic bases of different traits are associated with different ecological factors, causing the expression of inbreeding depression differed in phenotypic traits.

Key words: Ecological risk, Ecological health, Ecological security, Assessment method, Index system