Have you ever heard the phrase “ashes to ashes, dust to dust”? In conservation genetics, we sometimes say: “Neutral DNA to neutral DNA”—because traditional genetic diversity estimates largely focus on neutral regions of the genome that don’t affect function. But a new PNAS study flips that idea on its head—and shows that, at least for one species, those “neutral” parts of the genome actually reflect how much functional genetic variation remains.
⚠️ The big question: does neutral genetic diversity truly indicate a population’s health?
For decades, wildlife geneticists have relied on neutral DNA—portions of the genome unrelated to genes—to infer genetic health and adaptive potential. It’s simpler, cheaper, and was long considered a proxy for how well a population can survive environmental change. But critics argued: neutral diversity might not capture what’s biologically meaningful, like adaptation genes or mutation load.
That’s the question Samarth Mathur, Andrew Mason, Gideon Bradburd, and Lisle Gibbs tackled with the endangered Eastern Massasauga rattlesnake (Sistrurus catenatus). With a chromosome-level reference genome and whole-genome sequencing of 110 snakes, they were able to directly compare regions of neutral DNA with regions carrying real functional weight.
🧬 What they discovered will surprise you
The results were striking: neutral genetic diversity was indeed a strong predictor of functional genetic health in these rattlesnakes. Populations with higher neutral diversity also maintained more adaptive genetic variation and carried fewer harmful mutations.
This finding has huge implications for conservation. It suggests that our traditional, cheaper methods of assessing genetic health might be more reliable than critics suggested—at least for some species.
🎯 Why this matters for conservation
The study provides crucial validation for decades of conservation genetics work. When resources are limited (and they always are), knowing that neutral genetic surveys can reliably indicate a population’s adaptive potential is game-changing.
For the Eastern Massasauga specifically, this research helps prioritize which populations most urgently need genetic rescue—those with the lowest neutral diversity are likely struggling with both adaptive potential and mutation load.
The implications extend far beyond rattlesnakes. If this relationship holds across other species, it could streamline conservation genetic assessments worldwide, making them more accessible to resource-limited conservation programs.