The Poetry of the Convergent Lizards

Convergence at White Sands

Whiptails and fencers scurry and make haste,
cross White Sands their paths converge and pace.
Tho' differing by both origin and type,
their causal genotypes follow trace.

Independent mutations had aligned,
and were by adaptation refined.
Genes and the surroundings got a hitch,
when their ecosystems intertwined.

Nature reduced the melanin of two,
with methods mechanically askew.
They evolved cryptic gypsum like match,
avoiding predatory subdue.

Even when some common genes play actor,
trait expression is a big factor.
So says Rosenblum quite sincere
in a research paper found HERE.



In case that's not quite enough info here's the abstract:
There are many striking examples of phenotypic convergence in nature, in some cases associated with changes in the same genes. But even mutations in the same gene may have different biochemical properties and thus different evolutionary consequences. Here we dissect the molecular mechanism of convergent evolution in three lizard species with blanched coloration on the gypsum dunes of White Sands, New Mexico. These White Sands forms have rapidly evolved cryptic coloration in the last few thousand years, presumably to avoid predation. We use cell-based assays to demonstrate that independent mutations in the same gene underlie the convergent blanched phenotypes in two of the three species. Although the same gene contributes to light phenotypes in these White Sands populations, the specific molecular mechanisms leading to reduced melanin production are different. In one case, mutations affect receptor signaling and in the other, the ability of the receptor to integrate into the melanocyte membrane. These functional differences have important ramifications at the organismal level. Derived alleles in the two species show opposite dominance patterns, which in turn affect their visibility to selection and the spatial distribution of alleles across habitats. Our results demonstrate that even when the same gene is responsible for phenotypic convergence, differences in molecular mechanism can have dramatic consequences on trait expression and ultimately the adaptive trajectory.



Rosenblum, E., Rompler, H., Schoneberg, T., & Hoekstra, H. (2009). Molecular and functional basis of phenotypic convergence in white lizards at White Sands Proceedings of the National Academy of Sciences DOI: 10.1073/pnas.0911042107