Who’s your daddy? On the identity and distribution of the paternal hybrid ancestor of the parthenogenetic gecko Lepidodactylus lugubris (Reptilia: Squamata: Gekkonidae)

The widespread parthenogenetic gecko Lepidodactylus lugubris is comprised of several clonal lineages, at least one of which has been known for some time to have originated from hybridization between its maternal ancestor, Lepidodactylus moestus, and a putatively undescribed paternal ancestor previously known only from remote islands in the Central Pacific. By integrating new genetic sequences from multiple studies on Lepidodactylus and incorporating new genetic sequences from previously sampled populations, we recovered a phylogenetic tree that shows a close genetic similarity between the generally hypothesized paternal hybrid ancestor and a recently described species from Maluku (Indonesia), Lepidodactylus pantai. Our results suggest that the paternal hybrid ancestor of at least one parthenogenetic clone of L. lugubris is conspecific with L. pantai and that the range of this species extends to Palau, the Caroline Islands, the Kei Islands, Wagabu, and potentially other small islands near New Guinea. Deeper genetic structure in the western (Palau, Maluku) versus eastern (eastern Melanesia, Micronesia, Polynesia) part of this species’ range suggests that the western populations likely dispersed via natural colonization, whereas the eastern populations may be the result of human-mediated dispersal. The potential taxonomic affinities and biogeographic history should be confirmed with further morphological and genetic analyses, including research on L. woodfordi from its type locality, which would have nomenclatural priority if found to be conspecific with L. pantai. We recommend referring to the wide-ranging sexual species as Lepidodactylus pantai until such a comparison can be made.

Perfecting the Imperfect: Introducing dorsoventral patterning into adult regenerating lizard tails with gene-edited embryonic neural stem cells.

Lizards are able to regrow amputated tails, but the lizard tail regenerative process fails to recapitulate the dorsoventral patterning achieved during embryonic tail development. Regenerated lizard tails form ependymal tubes (ETs) that, like embryonic tail neural tubes (NTs), induce cartilage differentiation in surrounding cells via sonic hedgehog (Shh) signaling. Embryonic NTs are, themselves, dorsoventrally patterned, with Pax7+ Shh- dorsal roof plate domains that restrict cartilage skeletal formation induced by Pax7- Shh+ floor domains to ventral tail regions. However, adult regenerated tail ETs lack characteristically roof plate-associated structures and express Shh throughout their circumferences, resulting in the formation of unpatterned cartilage tube skeletons. Both NTs and ETs contain populations of neural stem cells (NSCs), but only embryonic NSC populations are able to differentiate into roof plate identities and neurons. Embryonic NSCs transplanted into regenerated tail ETs retain the capacity to form roof domains but are ultimately ventralized by the unchecked hedgehog signaling of regenerated lizard tail environments. We hypothesized that only the simultaneous repression of hedgehog signaling and enhancement of NCS roof plate differentiation capacity would induce patterning in lizard ETs and, hence, regenerated cartilage. This was tested through the use of a novel genetic engineering process in which NSCs are isolated from embryos of the parthenogenetic lizard Lepidodactylus lugubris, gene-edited in vivo, and implanted back into clonally-identical adults to regulate tail regeneration. Embryonic lizard NSC lines unresponsive to hedgehog stimulation were generated through the use of CRISPR/Cas9 technologies to knockout (KO) the signaling regulator smoothened (Smo). Exogenous Smo KO NSCs were injected into adult tail spinal cords, where they engrafted to endogenous ependymal cell populations and contributed to dorsal domains in regenerated tail ETs. Embryonic Smo KO NSCs maintained roof plate identities in vivo, and lizards treated with edited NSCs regrew tails that lacked cartilage in dorsal regions. These studies represent an important milestone in the creation of the first regenerated lizard tails with dorsoventrally patterned ETs and skeletal tissues.

First record of the invasive gecko, Lepidodactylus lugubris Duméril & Bibron, 1836 in mainland Chile (Squamata, Gekkonidae)

In Chile, the presence of Mourning Gecko, Lepidodactylus lugubris Duméril & Bibron, 1836 has been recognized for Easter Island (Rapa Nui) from late 19th century. Here, we report the first observation of a juvenile specimen of L. lugubris in an urban zone of Santiago, Región Metropolitana, mainland Chile, representing the southernmost non-insular record in America for this invasive species. Moreover, an updated distributional map of L. lugubris for South America and the Antilles is provided.