A new study reveals the lasting genetic impacts of increased isolation among different tiger subpopulations. The research, detailed in a new paper published this week in the journal Molecular Biology and Evolution, shows how genomics can help guide conservation efforts toward wild tigers and other species, said study co-leader Elizabeth Hadly, the Paul S. and Billie Achilles Professor in Environmental Biology.
“The increasing dominance of humans across the world means that our understanding of which attributes of species and populations are best suited to the Anthropocene becomes ever more important,” said Hadly, referring to the proposed geological epoch marked by significant human impact on the environment.
“Some populations are well adapted to a future dominated by humans and our new climates and others are not, so any type of management of species should be informed by what we can glean from their genomes,” added Hadly, who is also a senior fellow at the Stanford Woods Institute for the Environment. “Conservation genomics is far from a perfect science, but this tiger study hints at the power of adequate sampling across both the species range and its genome.”
The study reveals that the world’s existing tiger subspecies began exhibiting signs of dramatic and recent contractions starting only around 20,000 years ago – a period that coincided with both the global transition out of the Pleistocene Ice Age and the rise of human dominance in Asia. Each subspecies of tiger the team studied showed unique genomic signatures as a consequence of their increasing isolation from one another.
While many studies investigating endangered species using genomics sequences from a single or just a few individuals, this work reiterates that individuals are not likely to be representative of a population or species status. Further work investigating the consequences of potential inbreeding and diversity declines across the subspecies are needed.
“As genomics has become available to conservation, it is apparent that collaborative studies to investigate the diversity within species are critical,” said study first author Ellie Armstrong, a Stanford PhD student in Hadly’s lab. “Inferences made from single genomes, while excellent additions to our knowledge of diversity in general, cannot be extrapolated to entire species, especially when using captive animals to infer adaptation to complex habitat change.”