Although there has been some exchange of populations in the East, this study suggests that genetic differences between African and Asian leopards began with the first migration. (approximately 500,000 years ago).
On the other hand, genetic analysis usually requires fresh tissue samples. However, analysis of museum samples allowed researchers to recover population genome information that had previously been driven to extinction for at least several decades.
Thus, the researchers were able to obtain nuclear genomic data (the entire DNA) of leopards in their current and historical distribution, discovering new details about their global population. Also, since their separation, Asian leopard populations have experienced fewer genetic changes than African leopards, probably because they are more dispersed across the continent.