Initiation of speciation across multiple dimensions in a rock-restricted, tropical lizard.

Population isolation and concomitant genetic divergence, resulting in strong phylogeographical structure, is a core aspect of speciation initiation. If and how speciation then proceeds and ultimately completes depends on multiple factors that mediate reproductive isolation, including divergence in genomes, ecology and mating traits. Here we explored these multiple dimensions in two young (Plio-Pleistocene) species complexes of gekkonid lizards (Heteronotia) from the Kimberley-Victoria River regions of tropical Australia. Using mitochondrial DNA screening and exon capture phylogenomics, we show that the rock-restricted Heteronotia planiceps exhibits exceptional fine-scale phylogeographical structure compared to the codistributed habitat generalist Heteronotia binoei. This indicates pervasive population isolation and persistence in the rock-specialist, and thus a high rate of speciation initiation across this geographically complex region, with levels of genomic divergence spanning the "grey zone" of speciation. Proximal lineages of H. planiceps were often separated by different rock substrates, suggesting a potential role for ecological isolation; however, phylogenetic incongruence and historical introgression were inferred between one such pair. Ecomorphological divergence among lineages within both H. planiceps and H. binoei was limited, except that limestone-restricted lineages of H. planiceps tended to be larger than rock-generalists. By contrast, among-lineage divergence in the chemical composition of epidermal pore secretions (putative mating trait) exceeded ecomorphology in both complexes, but with less trait overlap among lineages in H. planiceps. This system-particularly the rock-specialist H. planiceps-highlights the role of multidimensional divergence during incipient speciation, with divergence in genomes, ecomorphology and chemical signals all at play at very fine spatial scales.

Composition of a chemical signalling trait varies with phylogeny and precipitation across an Australian lizard radiation.

The environment presents challenges to the transmission and detection of animal signalling systems, resulting in selective pressures that can drive signal divergence amongst populations in disparate environments. For chemical signals, climate is a potentially important selective force because factors such as temperature and moisture influence the persistence and detection of chemicals. We investigated an Australian lizard radiation (Heteronotia) to explore relationships between a sexually dimorphic chemical signalling trait (epidermal pore secretions) and two key climate variables: temperature and precipitation. We reconstructed the phylogeny of Heteronotia with exon capture phylogenomics, estimated phylogenetic signal in amongst-lineage chemical variation and assessed how chemical composition relates to temperature and precipitation using multivariate phylogenetic regressions. High estimates of phylogenetic signal indicate that the composition of epidermal pore secretions varies amongst lineages in a manner consistent with Brownian motion, although there are deviations to this, with stark divergences coinciding with two phylogenetic splits. Accounting for phylogenetic non-independence, we found that amongst-lineage chemical variation is associated with geographic variation in precipitation but not temperature. This contrasts somewhat with previous lizard studies, which have generally found an association between temperature and chemical composition. Our results suggest that geographic variation in precipitation can affect the evolution of chemical signalling traits, possibly influencing patterns of divergence amongst lineages and species.

Are Pheromones Key to Unlocking Cryptic Lizard Diversity?

Animals use mating traits to compete for, attract, and choose mates. Because mating traits influence mate choice, the divergence of mating traits between populations can result in reproductive isolation. This can occur without associated morphological divergence, producing reproductively isolated cryptic species that are visually indistinguishable. Thus, identifying the mating traits in morphologically conservative groups is key to resolving diversity and speciation processes. Lizards contain many such groups, with phylogeographic studies often revealing highly divergent but morphologically cryptic lineages within species. Considering that cryptic lizard species can be sympatric but morphologically indistinguishable, we hypothesize that candidate species will exhibit divergent pheromones and that pheromones will have typically diverged more than morphology. To test this, we used gas chromatography to characterize pheromones (epidermal pore secretions) from 10 genetically divergent lineages of the Bynoe's gecko (Heteronotia binoei) species complex in northern Australia. Multivariate analyses of pheromone blends and morphology indicate that pheromones are lineage specific and have diverged relatively more than morphology. Such specificity suggests that pheromones influence behavioral isolation in this morphologically conservative lizard radiation. These results suggest that pheromone data may unlock the tremendous cryptic diversity currently being uncovered in many lizard groups.

Beauty in the eye of the beholder: a new species of gecko (Diplodactylidae: Lucasium) from inland north Queensland, Australia.

The Einasleigh Uplands bioregion of central north Queensland, Australia, harbours a unique suite of reptiles that have begun to receive significant attention in the last 20 years. This has resulted in a number of new reptile species being described, and recognition that others await description. We describe a new species of Lucasium Wermuth, 1965 from the western Einasleigh Uplands. Lucasium iris sp. nov. is genetically distinct and morphologically diagnosable from all congeners by its large size, long and narrow tail, nares in contact with rostral scale, homogeneous body scales, distinct vertebral stripe, and paired, enlarged, apical subdigital lamellae. It is known from low rocky hills in a localised area of the Gregory Range, has the most restricted known distribution of any Lucasium, and is the only Lucasium endemic to Queensland. The new species appears most closely related to L. steindachneri (Boulenger, 1885), based on mitochondrial DNA sequences, but has a colour-pattern more similar to L. immaculatum Storr, 1988. All three of these species occur in the Einasleigh Uplands, but only L. steindachneri is known to occur in sympatry with L. iris sp. nov. In addition to the description of the new species, we present records of Lucasium immaculatum from the Einasleigh Uplands, which represent a significant known range extension.

A new species of rock-dwelling gecko (Gekkonidae: Gehyra) from the Mt Surprise region of northern Queensland, Australia.

We describe a new species of rock-dwelling Gehyra Gray, 1834 (Gekkonidae) from the Einasleigh Uplands of inland north Queensland, Australia. Morphological, ecological, and molecular data clearly support the new species as distinct and place it within the 'australis group'. Gehyra electrum sp. nov. is distinguished from congeners by a combination of medium adult size (SVL 46-50 mm), an orange-brown to pinkish-orange background colouration with a pattern of distinct whitish spots and irregular black to purple-brown blotches or bars, possessing 7-8 undivided subdigital lamellae on the expanded portion of the fourth toe, and a wedge-shaped mental scale that separates the inner-postmental scales along 40% or more of their length. Gehyra electrum sp. nov. is a rock specialist currently known only from granite outcrops of the Mt Surprise region, Queensland. This is the second recently described Gehyra from the Einasleigh Uplands and adds to the growing number of endemic reptiles recognised in the region.

A new species of velvet gecko (Diplodactylidae: Oedura) from sandstone habitats of inland north Queensland, Australia.

We describe a new species of velvet gecko (Diplodactylidae: Oedura) from the sandstone ranges of central-north Queensland, Australia. Oedura argentea sp. nov. is a medium-sized (SVL 61-80 mm) gecko that is distinguished from its congeners by a combination of its relatively small size, a pattern of 5-6 dark-edged pale transverse bands from neck to pelvis, a silvery iris, a slender tail, a single cloacal spur, and in possessing 14-22 pre-cloacal pores in males. Oedura argentea sp. nov. is a sandstone specialist currently known only from the Gregory Range and nearby sandstone outcropping at Bulleringa National Park. Further surveys are required to determine the limits of distribution through this region. Oedura argentea sp. nov. is the fifth described species of Oedura in north-eastern Queensland. We also assess the name O. fracticolor De Vis, 1884 because it is an unresolved name pertaining to this general region. Based on colour-pattern and locality in the original description, we conclude that O. fracticolor is a senior synonym of O. castelnaui (Thominot, 1889); however, we propose that priority be overturned under Articles 23.9.1.1 and 23.9.1.2 of the ICZN (1999) and that the name O. fracticolor be regarded as nomen oblitum and O. castelnaui a nomen protectum.