First Reptile Gets its Genetic Code Sequenced

This week scientists announced they'd sequenced the first genetic code of a reptile – an achievement that Harvard biologist John Losos expects to help clarify some open questions about the genetic changes that underlay evolutionary changes.  The type of reptile they picked, an anole lizard, holds a particular fascination for biologists because on the Caribbean islands, different, unrelated species tend to evolve the exact same body-types and survival strategies, whether it's hiding in brush or disguising themselves as twigs.

A few weeks ago I wrote this column about the way these lizards can help test Stephen Jay Gould's thought experiment about running the clock back millions of years to see if evolution, if allowed to run again, would produce anything like the plants and animals we have today. Gould thought it certainly wouldn't produce humans, or anything like humans, since evolution is too dependent on random and unpredictable events, including the asteroid impact that killed off the dinosaurs.

We can't run the clock backwards but we can learn something by watching different populations of animals evolve independently on different islands.  The end result is the extremely similar from one island to the next, said Harvard biologist Jonathan Losos, who was part of a collaboration of dozens of scientists involved in the genetic sequencing project. They know, for instance, that some of these lizards evolved short legs independently on different islands. Now they can start to ask how that happened – whether they modified the same genes or different ones to get there.

They might also learn why these lizards tend to evolve in parallel when other animals don't. Is it something in their DNA?

The genome analysis, which was published this week in the journal Nature, looked at the green anole lizard – (Anolis carolinesis) which lives in the Southeastern United States. It's one of about 400 species of anole. You can read more about the paper here.

Losos qualifies the statement about this being the first reptile to have its genetic code sequenced. Several birds have been sequenced, and yes, he said birds are reptiles. That's not just because they're descendants of the dinosaurs but because they're more closely related to crocodiles than crocodiles are related to lizards and other reptilian groups.  But that's a topic for another day.