Sex determination and optimal development in the Moorish gecko,Tarentola mauritanica

Under temperature sex determination (TSD), sex is determined by temperature during embryonic development. Depending on ecological and physiological traits and plasticity, TSD species may face demographic collapse due to climate change. In this context, asymmetry in bilateral organisms can be used as a proxy for developmental instability and, therefore, deviations from optimal incubation conditions. Using Tarentola mauritanica gecko as a model, this study aimed first to confirm TSD, its pattern and pivotal temperature, and second to assess the local adaptation of TSD and variation of asymmetry patterns across four populations under different thermal regimes. Eggs were incubated at different temperatures, and hatchlings were sexed and measured. The number of lamellae was counted in adults and hatchlings. Results were compatible with a TSD pattern with males generated at low and females at high incubation temperatures. Estimated pivotal temperature coincided with the temperature producing lower embryonic mortality, evidencing selection towards balanced sex ratios. The temperature of oviposition was conservatively selected by gravid females. Asymmetry patterns found were likely related to nest temperature fluctuations. Overall, the rigidity of TSD may compromise reproductive success, and demographic stability in this species in case thermal nest choice becomes constrained by climate change.     

Molecular evidence for Gondwanan origins of multiple lineages within a diverse Australasian gecko radiation

Aim Gondwanan lineages are a prominent component of the Australian terrestrial biota. However, most squamate (lizard and snake) lineages in Australia appear to be derived from relatively recent dispersal from Asia (< 30 Ma) and in situ diversification, subsequent to the isolation of Australia from other Gondwanan landmasses. We test the hypothesis that the Australian radiation of diplodactyloid geckos (families Carphodactylidae, Diplodactylidae and Pygopodidae), in contrast to other endemic squamate groups, has a Gondwanan origin and comprises multiple lineages that originated before the separation of Australia from Antarctica. Location Australasia. Methods Bayesian (beast ) and penalized likelihood rate smoothing (PLRS) (r 8s ) molecular dating methods and two long nuclear DNA sequences (RAG‐1 and c‐mos) were used to estimate a timeframe for divergence events among 18 genera and 30 species of Australian diplodactyloids. Results At least five lineages of Australian diplodactyloid geckos are estimated to have originated > 34 Ma (pre‐Oligocene) and basal splits among the Australian diplodactyloids occurred c. 70 Ma. However, most extant generic and intergeneric diversity within diplodactyloid lineages appears to post‐date the late Oligocene (< 30 Ma). Main conclusions Basal divergences within the diplodactyloids significantly pre‐date the final break‐up of East Gondwana, indicating that the group is one of the most ancient extant endemic vertebrate radiations east of Wallace’s Line. At least five Australian lineages of diplodactyloid gecko are each as old or older than other well‐dated Australian squamate radiations (e.g. elapid snakes and agamids). The limbless Pygopodidae (morphologically the most aberrant living geckos) appears to have radiated before Australia was occupied by potential ecological analogues. However, in spite of the great age of the diplodactyloid radiation, most extant diversity appears to be of relatively recent origin, a pattern that is shared with other Australian squamate lineages.     

Small and overlooked: Phylogeny of the genus Trigonodactylus (Squamata: Gekkonidae), with the first record of Trigonodactylus arabicus from Jordan

Geckos of the genus Trigonodactylus are widely distributed in the sand deserts of the Arabian Peninsula. Three species of this genus are currently recognized, with a fourth one, Stenodactylus pulcher, which placement within Trigonodactylus has been tentatively suggested, but not yet confirmed. We present a phylogenetic analysis of the genus Trigonodactylus with new specimens collected in central Saudi Arabia and southern Jordan. New genetic data has been generated from three mitochondrial markers to investigate the phylogenetic relationships of all species of the genus and to assess the putative generic assignment of S. pulcher. Our results confirm that S. pulcher indeed belongs within Trigonodactylus, branching as a sister lineage to all other species of the genus. The new samples cluster within Trigonodactylus arabicus, thus confirming the genetic homogeneity of the species across its large and seemingly inhospitable range. The new specimen collected in southern Jordan represents the first record for the country and a considerable range extension to the northwest from all previously reported localities. Our findings and discovery of a new species for Jordan highlight the need of more field surveys to be carried out in the underexplored parts of Jordan and northern Saudi Arabia, as these places still hold a potential for new discoveries and are crucial for understating the biogeography of the Arabian herpetofauna.     

Phylogeography of sexual Heteronotia binoei (Gekkonidae) in the Australian arid zone: climatic cycling and repetitive hybridization

The biota of much of continental Australia have evolved within the context of gradual aridification of the region over several million years, and more recently of climatic cycling between relatively dry and humid conditions. We performed a phylogeographical study of three sexual chromosome races of the Heteronotia binoei complex of geckos found throughout the Australian arid zone. Two of these three races were involved in two separate hybridization events leading to parthenogenetic lineages (also H. binoei), and the third is widespread and broadly sympatric with the parthenogens. Based on our analyses, the three sexual races diversified approximately 6 million years ago in eastern Australia, during a period of aridification, then each moved west through northern, southern, and central dispersal corridors to occupy their current ranges. In each case, the timing of major phylogeographical inferences corresponds to inferred palaeoclimatic changes in continental Australia. This scenario provides a simple explanation for diversification, secondary contact, and hybridization between the races. However, data presented elsewhere indicate that formation of the parthenogens was considerably more recent than the westward expansion of the hybridizing races, and that multiple hybridization events were geographically and temporally distinct. We suggest that cyclical climate changes may have led to regional range changes that facilitated hybridization between the races, which are not currently known to be in sympatry.     

Extinct,obscure or imaginary: The lizard species with the smallest ranges

Aim

Small geographic ranges make species especially prone to extinction from anthropogenic disturbances or natural stochastic events. We assemble and analyse a comprehensive dataset of all the world's lizard species and identify the species with the smallest ranges—those known only from their type localities. We compare them to wide‐ranging species to infer whether specific geographic regions or biological traits predispose species to have small ranges.

Location

Global.

Methods

We extensively surveyed museum collections, the primary literature and our own field records to identify all the species of lizards with a maximum linear geographic extent of <10 km. We compared their biogeography, key biological traits and threat status to those of all other lizards.

Results

One in seven lizards (927 of the 6,568 currently recognized species) are known only from their type localities. These include 213 species known only from a single specimen. Compared to more wide‐ranging taxa, they mostly inhabit relatively inaccessible regions at lower, mostly tropical, latitudes. Surprisingly, we found that burrowing lifestyle is a relatively unimportant driver of small range size. Geckos are especially prone to having tiny ranges, and skinks dominate lists of such species not seen for over 50 years, as well as of species known only from their holotype. Two‐thirds of these species have no IUCN assessments, and at least 20 are extinct.

Main conclusions

Fourteen per cent of lizard diversity is restricted to a single location, often in inaccessible regions. These species are elusive, usually poorly known and little studied. Many face severe extinction risk, but current knowledge is inadequate to properly assess this for all of them. We recommend that such species become the focus of taxonomic, ecological and survey efforts.

     

Habitat-dependent thermal regimes of two hawaiian geckos (Reptilla: gekkonidae)

1. 1.Effects of habitat on the thermal regime were investigated in two diurno—nocturnal geckos in Hawaii.

2. 2.In trees Hemidactylus frenatus thermoregulated in daytime with body temperature (BT) above air temperture (AT); in houses some thermoregulated likewise in daytime but mainly the species thermoregulated at night, on electric lamps, to the same BT as in trees by day.

3. 3.Lepidodactylus lugubris in trees thermoregulated in daytime, its BT lower than in H. frenatus. In the rocks it had at night a BT resembling that in trees in daytime, because the thermal cycle in rock crevices lagged behind outside AT.

4. 4.The flexibility of these geckos in thermal regime and activity cycle preadapts them to both migration and invasion of houses.

ADAPTIVE RADIATION OF DAY-GECKOS (PHELSUMA) IN THE SEYCHELLES ARCHIPELAGO: A PHYLOGENETIC ANALYSIS

A phylogenetic analysis using characters derived from mitochondrial DNA was used to show that the species of Phelsuma in the Seychelles Islands represent a single, monophyletic lineage that has diversified as a result of both historical and ecological factors. In the distant past, the Seychelles archipelago was physically invaded by a single species of Phesluma. Separate eustatic sea level changes likely led first to allopatric speciation and then to the secondary contact of these sister species. Differences in the relative timing of the secondary contact between island groups resulted in P. sundbergi evolving an intermediate body size in the group of islands associated with Mahé and a large body size, while sympatric with P. astriata, in the group of islands associated with Praslin. Ecological information was used to support the conclusion that the actual evolutionary mechanism for the body size shift was a response to frequency dependent natural selection of P. sundbergi in single-species and two-species competitive regimes.     

The formulation of a national strategy for biological control of possums and bovine Tb

Abstract

The Government has designated the control of possums and bovine Tb a National Science Strategy (NSS) research area. An NSS Committee has been appointed by the Ministry of Research Science and Technology, commissioned to “identify, coordinate and promote national priorities for possum and tuberculosis (Mycobacterium bovis) related research in order that threats both to New Zealand's export markets and to conservation values can be eliminated”.     

Parallel origins of duplications and the formation of pseudogenes in mitochondrial DNA from parthenogenetic lizards (Heteronotia binoei; Gekkonidae)

Summary Analysis of mitochondrial DNAs (mtDNAs) from parthenogenetic lizards of theHeteronotia binoei complex with restriction enzymes revealed an 5-kb addition present in all 77 individuals. Cleavage site mapping suggested the presence of a direct tandem duplication spanning the 16S and 12S rRNA genes, the control region and most, if not all, of the gene for the subunit 1 of NADH dehydrogenase (ND1). The location of the duplication was confirmed by Southern hybridization. A restriction enzyme survey provided evidence for modifications to each copy of the duplicated sequence, including four large deletions. Each gene affected by a deletion was complemented by an intact version in the other copy of the sequence, although for one gene the functional copy was heteroplasmic for another deletion. Sequencing of a fragment from one copy of the duplication which encompassed the tRNA^leu(UUR) and parts of the 16S rRNA and ND1 genes, revealed mutations expected to disrupt function. Thus, evolution subsequent to the duplication event has resulted in mitochondrial pseudogenes. The presence of duplications in all of these parthenogens, but not among representatives of their maternal sexual ancestors, suggests that the duplications arose in the parthenogenetic form. This provides the second instance inH. binoei of mtDNA duplication associated with the transition from sexual to parthenogenetic reproduction. The increased incidence of duplications in parthenogenetic lizards may be caused by errors in mtDNA replication due to either polyploidy or hybridity of their nuclear genomes.