Tough Blood

Lizards exposed to lead often have impaired balance, speed, and endurance.  

However, a new study found that there might be some exceptions. 

Researchers have discovered that brown anole lizards (Anolis sagrei) in New Orleans have the highest blood-lead levels ever recorded in a vertebrate, exceeding all previously reported data for fish, amphibians, birds, reptiles, and mammals. 

“What’s astonishing is that these lizards aren’t just surviving, they’re thriving with a lead burden that would be catastrophic for most other animals,” study author Alex Gunderson said in a statement.  

Lead is a pervasive environmental pollutant with serious health implications, particularly in urban areas. The study highlighted the enduring legacy of lead contamination in New Orleans and the complicated ways organisms have adapted, or failed to, to the polluted environment. 

For the study, researchers tested the creatures’ balance, sprint speed, and endurance to see how lizards were affected. They found that lizards are capable of withstanding lead levels about 10 times higher than the already extreme concentrations found in the field before starting to show declines in performance. 

“These animals are performing at full capacity despite record-setting lead levels, making them one of the most, if not the most, lead-tolerant animals known to science,” study author Annelise Blanchette said in the statement.  

When researchers examined the animals’ brain and liver tissue transcriptomes, they found only minor impacts from lead exposure. However, several genes linked to metal ion regulation and oxygen transport showed alterations. 

The study results raise new questions about how these reptiles manage to endure such toxic exposure, and whether those mechanisms might one day help guide therapies for humans and other species. 

“We need to reevaluate what we know about toxicity thresholds in vertebrates,” Gunderson said. “If we can figure out what’s protecting them, we might uncover strategies that could help mitigate heavy metal poisoning in people and other species.”