Survival through agricultural takeovers
At night on the trails of three accessible forest patches in 2016, the authors walked, using torchlights to find and record chameleons.
“The first one we found was in the transition zone on the forest edge, where there are some trees but mostly maize and cassava plants,” Tolley said. “When we found it we got goosebumps and just started jumping around. We didn’t know if we would get any more, but once we got into the forest there were plenty, although I don’t know how long that will last.”
The researchers found seven adult chameleons along a footpath just inside the first forest patch of Malawi Hills; 10 chameleons inside a site over 6 kilometers (4 miles) southwest of the first; and 21 adult chameleons plus 11 young and hatchlings inside the patch at Mikundi, the location of the 1998 release.
Pygmy chameleons still face threats
After snipping 2-millimeter-long (0.1-inch-long) tail clips from some adult chameleons, the authors did genetic analysis. The chameleons’ genetic diversity was normal in comparison to that of other chameleons and small-bodied reptile species, the authors found. But there were significant differences in genetic structure between populations in different areas, suggesting that humans fragmenting the forest patches had disrupted the breeding ability between chameleons on neighboring patches and therefore their gene flow — an impact that increases extinction risk due to fewer options for mates, the authors wrote.
However, the authors might have overestimated the amount of genetic diversity between populations by not accounting for the way that some DNA is inherited, said Eric Routman, a professor emeritus of biology at San Francisco State University, who wasn’t involved in the study.
“And even if they had lots of loci and good genetic estimates, they have no estimate of these genetic parameters before the habitat fragmentation, so they can’t attribute any genetic effect to deforestation,” Routman added via email. “If I had been reviewing this paper, I would have recommended major revisions to the manuscript. Essentially, the genetic part of their study is inconclusive.”
The authors think effects of deforestation on genetic diversity could take time to appear. But to prevent the chameleon species from reaching a point of no return, the rainforest loss requires immediate attention, Tolley said.
“Urgent conservation action is needed, including halting of forest destruction and recovery of habitat to promote connectivity. Although part of the Malawi Hills falls within a Key Biodiversity Area (Matandwe Forest Reserve), most of the forest falls outside the reserve boundary, and the effectiveness of the forest reserve is questionable, given that most of the destruction has been within its boundaries,” the authors wrote. “Although extending the reserve to encompass all the forest patches would be a first step, measures are needed to avert the destruction of the remaining patches.”
These efforts would be important also for any other species that possibly live among these chameleons, the authors wrote. And there could be more pygmy chameleons in the patches they weren’t able to explore, they said.
For the little creatures Polley described as gentle and beautiful, “both the planning and the recommended actions require strong leadership, personnel, stakeholder engagement, including with government departments, and sufficient funding to ensure success,” the authors added.
Rare species thought extinct is clinging to survival, study finds