Chemical biology: Paper alert

A selection of interesting papers that were published in the two months before our press date in major journals most likely to report significant results in chemical biology.     

The demography and physiology of Melomys sp. (Rodentia: Muridae) in the Mitchell Plateau area, Kimberley, Western Australia

Populations of a mosaic-tailed rat ( Melomys sp.) were studied for one year in vine-thicket and mangrove habitats in the Mitchell Plateau area of the tropical Kimberley district of Western Australia. Demographic and physiological (haematological values, androgens, corticosteroids and their binding proteins) parameters were measured together with parasite prevalence and electrophoretic protein variation. Seasonal variation occurred in most parameters measured. Higher values were found in the vine-thicket for number of sympatric mammal species, growth rate of immatures and androgens. Higher values were found in the mangroves for population density, survival, size at sexual maturity, body weight, home range overlap, albumins, total and free-corticosteroids and parasite prevalence. The phenotypic frequencies of two protein polymorphisms (albumin and 6–phosphogluconate dehydrogenase) differed between sites, while a third (adenosine deaminase) showed no between-site differences; these suggest differential selection between the adjacent habitats which are separated by 10 km. The overall physiological response of Melomys was more entrained to seasonal variation in the vine-thicket than in the mangroves, which is in accord with the relative variation in the vegetation and temperature in the two areas. It is hypothesized that the greater population density in the mangroves results in behavioural feedback through the hypothalamo-pituitary-adrenal axis. This results in increased stress (higher free-corticosteroid levels) which slows the growth rate and the onset of sexual maturity. The study is the first to indicate that such a mechanism, commonly proposed for temperate small mammals, may operate in tropical areas.     

Trends in lizard translocations in New Zealand between 1988 and 2013

There is growing concern about mitigation-driven translocations that move animals from anthropogenic threats at donor sites because of their failure rate and lack of application of scientific principles and best practice. We reviewed all known lizard translocations in New Zealand between 1988 and 2013 and identified 85 translocations of 30 lizard taxa to 46 release sites. Most translocations (62%) were motivated by conservation goals for the species or the release site, and one-third were mitigation-driven translocations, typically motivated by habitat loss due to development. Mitigation-driven translocations began in 2003, and since that time have equalled the number of conservation-motivated translocations. Conservation-motivated translocations usually released lizards on islands without mammalian predators, whereas mitigation-driven translocations usually relocated lizards to mainland sites with introduced predators. Long-term monitoring has been sparse and often rudimentary. Eight lizard translocations have recorded population growth, including one mitigation-driven translocation that was into a fenced reserve. Research on commonly used management techniques to mitigate human-related impacts is recommended to establish whether these techniques benefit lizards in the long term.     

The effect of behaviour and body weight on the mechanical design of horns

A review of the behaviour of bovids and cervids when fighting suggests that it is only the dimensions of the base of horns and antlers which are important mechanically in their design. A fourth power function of the diameter of the base of a horn (the second moment of area (I)) increases linearly with body weight so that there is the same maximum stress in the horn during fighting. This is consistent with the efficient use of materials and is found to be the case for different types of fighting. Sheep and goats fight most forcefully and have a higher ratio of I to body weight than antelopes and deer, which tend to use less forceful wrestling.     

Biogeography of Indonesian snakes

The islands of eastern Indonesia occupy the major zone of contact and overlap between the reptile faunas of the Asian and Australo–Papuan regions. A survey of reptiles on twenty-eight islands in eastern Indonesia between 1988 and 1993 has documented several major range extensions and many new records of species on islands. The zoogeographic affinities of the snakes of Indonesian islands are re-examined in the light of both recent surveys and taxonomic research and coupled with that published previously. The major boundary in the snake fauna of Indonesia occurs between Sulawesi and the Lesser Sunda islands to the west and the northern and southern Maluku group of islands to the east; it corresponds to the major biogeographic boundary known as Weber's Line. The biogeographic affinities of the snakes of the Tanimbar islands are equivocal. The snake fauna of islands within the Lesser Sunda group indicate that separation between islands during the Pleistocene played a role in determining current assemblages and variation within species The islands of eastern Indonesia form biogeographic subregions that have relatively high levels of endemism and evidence of incipient speciation as a consequence of changes in sea-levels and climate during the Pleistocene.