Habitats of species are restricted by environmental and genetic factors. If organisms could adapt to different environments, they can expand their distribution. Hence, an ability of adaptation to new environments (evolvability) is important determining the habitat range. However, actual genetic factors related to evolvability, these factors are not clear. It is important to clarify the evolvability which contributes to maintenance and expansion of the habitat range. We focused gene duplication as a mechanism which produces genetic variations for evolution. Duplicated genes are released from functional constraints, and tend to accumulate mutations. We hypothesized that gene duplications have established the genetic basis for adaptation to new environments, and we tested whether there is a correlation between the environmental adaptation capacity and the proportion of duplicated genes (PD). We used whole genome sequenced 16 species in rodents and primates. The amino acid sequences of all genes and their habitats were obtained from database, and duplicated genes were identified by homogeny search. The habitat diversity was estimated from the climate information. The result showed that there was a significant correlation. We propose that PD can be used as an index predicting species which are limited ability to adapt to intense environmental changes.