Long-term thermal conditions on the nesting beaches of green turtles on Ascension Island

On 2 of the major nesting beaches used by green turtles Chelonia mydas on Ascension Island, we measured the sand temperature at nest depths throughout the year. For both beaches, the sand temperature was strongly correlated (r2 >= 0.94) with air temperature. We therefore used past records of air temperature to reconstruct sand temperatures on the different beaches throughout the nesting season between 1985 and 1998. This analysis showed that inter-annual differences in sand temperature were small and, while there were consistent thermal changes during the nesting season, over the 14 yr there was little overlap in the temperatures on the 2 beaches, with one being 2.6°C warmer, on average, than the other. This work suggests that inter-beach thermal variation is the major mechanism by which a range of incubation temperatures are realised on Ascension Island and hence is likely to facilitate the production of hatchlings of both sexes.

The navigational feats of green sea turtles migrating from Ascension Island investigated by satellite telemetry

Previous tagging studies of the movements of green turtles (Chelonia mydas) nesting at Ascension Island have shown that they shuttle between this remote target in the Atlantic Ocean and their feeding grounds on the Brazilian coast, a distance of 2300 km or more. Since a knowledge of sea turtle migration routes might allow inferences on the still unknown navigational mechanisms of marine animals, we tracked the postnesting migration of six green turtle females from Ascension Island to Brazil. Five of them reached the proximity of the easternmost stretch of the Brazilian coast, covering 1777 to 2342 km in 33 to 47 days. Their courses were impressively similar for the first 1000 km, with three turtles tracked over different dates following indistinguishable paths for the first 300 km. Only the sixth turtle made some relatively short trips in different directions around Ascension. The tracks show that turtles (i) are able to maintain straight courses over long distances in the open sea; (ii) may perform exploratory movements in different directions; (iii) appropriately correct their course during the journey according to external information; and (iv) initially keep the same direction as the west–south–westerly flowing current, possibly guided by chemical cues.

Inter- and intra-beach thermal variation for Green Turtle nests on Ascension Island, South Atlantic

Nest temperatures for green turtles (Chelonia mydas) nesting on Ascension Island, South Atlantic (7°57'S 14°22'W), were examined. Temperature probes were placed into nests on two beaches, Long Beach (26 nests) and North East Bay (8 nests). Within these beaches there was relatively little thermal variation (SD of nest temperature was 0.32°C for Long Beach and 0.30°C for North East Bay). To examine inter-beach thermal variation temperature probes were buried at 55 cm on 12 beaches. Inter-beach thermal variation was large and was related to the beach albedo with the darkest beach (albedo, 016) being 4.2°C warmer than the lightest coloured beach (albedo, 0.73).

Genetic composition of the Ascension Island green turtle rookery based on mitochondrial DNA : implications for sampling and diversity

In species of conservation concern it is often difficult to be certain that population diversity and structure have been adequately characterised by genetic sampling. Since practical and financial constraints tend to be associated with increasing sample sizes in many conservation genetic studies, it is important to consider the potential for sampling error and bias due to inadequate samples or spatio-temporal structure within populations. We analysed sequence data from the mitochondrial DNA control region in a large sample (n = 245) of green sea turtles Chelonia mydas collected at the globally important rookery of Ascension Island, South Atlantic. We examined genetic diversity and structure among 10 sampling sites, 4 beach clusters and 4 nesting seasons, and evaluated the genetic composition of Ascension against other Atlantic nesting populations, including the well-studied rookery at Tortuguero (Costa Rica). Finally, we used rarefaction and GENESAMP analyses to assess the ability of different sample sizes to provide acceptable genetic representations of a population, using Ascension and Tortuguero as models. On Ascension, we found 13 haplotypes, of which only 3 had been previously observed in the rookery, and 5 previously undescribed. We detected no differentiation among beach clusters or sampling seasons, and only weak differentiation among the 3 primary nesting sites. The increased sample size for Ascension provided higher resolution and statistical power in describing genetic structure among all other known Atlantic rookeries. Our extrapolations showed that a maximum of 18 and 6 haplotypes are expected to occur in Ascension and Tortuguero, respectively, and that current sample sizes are sufficient to describe most of the variation. We recommend using rarefaction and GENESAMP analyses on a rookery-by-rookery basis to evaluate whether a sample set adequately describes mitochondrial DNA diversity, thus strengthening subsequent phylogeographic and mixed stock analyses, and management recommendations for conservation.

Genome sequence of Ensifer medicae strain WSM1115, an acid-tolerant Medicago-nodulating microsymbiont from Samothraki, Greece

Ensifer medicae (syn. Sinorhizobium medicae) strain WSM1115 forms effective nitrogen fixing symbioses with a range of annual Medicago species and is used in commercial inoculants in Australia. WSM1115 is an aerobic, motile, Gram-negative, non-spore-forming rod. It was isolated from a nodule recovered from the root of burr medic (Medicago polymorpha) collected on the Greek Island of Samothraki. WSM1115 has a broad host range for nodulation and N2 fixation capacity within the genus Medicago, although this does not extend to all medic species. WSM1115 is considered saprophytically competent in moderately acid soils (pHCaCl2 5.0) however, has failed to persist at field sites where soil salinity exceeded 10 ECe (dS/m). Here we describe the features of E. medicae strain WSM1115, together with genome sequence information and its annotation. The 6,861,065 bp high-quality-draft genome is arranged into 7 scaffolds of 28 contigs, contains 6,789 protein-coding genes and 83 RNA-only encoding genes, and is one of 100 rhizobial genomes sequenced as part of the DOE Joint Genome Institute 2010 Genomic Encyclopedia for Bacteria and Archaea-Root Nodule Bacteria (GEBA-RNB) project.

'PNG solution' turns to nightmare on Manus Island

 Analysis of the PNG Solution asylum seeker resettlement policy in the wake of protests at the Manus Island detention facility, the violent death of one asylum seeker and the injuring of others. 

The millipedes of Barrow Island, Western Australia (Diplopoda)

Six species of millipedes are recorded from Barrow Island, including three species of pin-cushion millipedes of the order Polyxenida, Lophoturus madecassus (Marquet and Condé, 1950) (Lophoproctidae), Unixenus mjoebergi (Verhoeff, 1924) (Polyxenidae) and Phryssonotus novaehollandiae (Silvestri, 1923) (Synxenidae), a single species of the order Spirobolida, Speleostrophus nesiotes Hoffman, 1994 (Trigoniulidae), and two species of the order Polydesmida, Boreohesperus dubitalis Car and Harvey, 2013 (Paradoxosomatidae) and one species of the family Haplodesmidae (genus and species indet.). Lophoturus madecassus is circum-tropical in distribution, Unixenus mjoebergi and Phryssonotus novaehollandiae are found also on mainland Australia, but the other three species are endemic to the island. Speleostrophus nesiotes is a highly modified troglobiotic species, currently listed as threatened by the Western Australian government. It is unclear at present whether the haplodesmid specimen is a troglobite.

Isolation breeds naivety : island living robs Australian varanid lizards of toad-toxin immunity via four-base-pair mutation

Since their introduction to the toad-free Australian continent cane toads (Bufo marinus) have caused a dramatic increase in naïve varanid mortality when these large lizards attempt to feed on this toxic amphibian. In contrast Asian–African varanids, which have coevolved with toads, are resistant to toad toxin. Toad toxins, such as Bufalin target the H1-H2 domain of the α1 subunit of the sodium-potassium-ATPase enzyme. Sequencing of this domain revealed identical nucleotide sequences in four Asian as well as in three African varanids, and identical sequences in all 11 Australian varanids. However, compared to the Asian–African varanids, the Australian varanids showed four-base-pair substitutions, resulting in the alteration in three of the 12 amino acids representing the H1-H2 domain. The phenotypic effect of the substitutions was investigated in human embryonic kidney (HEK) 293 cells stably transfected with the Australian and the Asian–African H1-H2 domains. The transfections resulted in an approximate 3000-fold reduction in resistance to Bufalin in the Australian HEK293 cells compared to the Asian–African HEK293 cells, demonstrating the critical role of this minor mutation in providing Bufalin resistance. Our study hence presents a clear link between genotype and phenotype, a critical step in understanding the evolution of phenotypic diversity.