Biologists Create New Lizard Species in Lab

This is not your average Frankenlizard story created by mad scientists bent on playing god. The whiptailed lizard is unusual in nature to start. It carries not just one set of genes but perhaps as many as four. Species of whiptails interbreed in nature and produce offspring but these are usually sterile. However, some hybrids are parthenogenic females meaning they duplicate chromosomes in their offspring without males providing a set of genes. This asexual process is named parthenogenisis. These clones are genetically distinct from either parental lineage. If the female clones then breed with a male they can produce offspring with three distinct sets of genes. A Harvard grad student searching for whiptails around Alamagordo, NM in 1967 found a whiptail with four distinct sets of genes: three from Aspidoscelis exsanguis and a fourth from Aspidoscelis inornata. Trés bizarre!

Dr. Neaves did not follow up on his discovery being more interested in stem cells and fertility. But molecular biologist Peter Baumann decided to study the lizards after learning of their unique genetic makeup. He and his colleagues tried breeding the various species to recreate the hybrid oddity. Most of the time their experiments failed, but when A. exsanguis (f) and A. inornata (m) were brought together in the same jar, they mated and produced female hybrids. Not only were they healthy, but they could clone themselves and so could their asexual offspring. Today scientists have a population of 200. Since they are genetically distinct from their progenitors, these are a new species of whiptailed lizard. As a consulting lizard expert put it, "It's not a Frankenstein genome manipulation. It's the lizards in cages doing their thing." The new species is named A. neavesi in honor of the lizard's original finder. [photo credit: P. Baumann]

Because of their unusual genesis some biologists familiar with the experiment are uncomfortable saying A. neavesi is a new, distinct species. It does not need to breed sexually since the females can duplicate a set of genes in each offspring. It does not maintain a single gene pool. The mutations acquired by one parthenogenic female is passed only to its offspring. For these reasons A. neavesi might be termed hybrid clones to more accurately describe its relationship to the tree of life. There is a lot to study in this unique reproduction process. For example a human with just one more copy of chromosome 21 leads to Downs Syndrome. How the lizard manages to survive and reproduce with fours sets of genes is a mystery. As one Harvard biologist said, " If you are rare, you are more likely to go extinct by chance." How true!