All the eggs in one basket: Are island refuges securing an endangered passerine?

Refuges for threatened species are important to prevent species extinction. They provide protection from a range of environmental and biotic stressors, and ideally provide protection against all threatening processes. However, for some species it may not be clear why some areas are refuges and others are not. The forty‐spotted pardalote (Pardalotus quadragintus) is an endangered, sedentary, cryptic and specialised bird endemic to the island of Tasmania, Australia. Having undergone an extreme range contraction over the past century the species is now mostly confined to a few small offshore island refuges. Key threatening processes to the species include habitat loss, wildfire, competition and predation. The ways in which these processes have molded the species’ contemporary range have not been clearly evaluated. Furthermore, the security of the remnant population within refuges is uncertain. To overcome this uncertainty we assessed key threats and established the population status in known refuges by developing a robust survey protocol within an occupancy modelling framework. We discuss our results in the context of planning trial reintroductions of this endangered species in suitable habitat across its former range. We found very high occupancy rates (0.75–0.96) at two refuges and in suitable conditions, the species was highly detectable (p, 0.43–0.77). At a third location our surveys indicated a local extinction, likely due to recent wildfire. We demonstrate that all refuges are at high risk of one or more threatening processes and the current distribution across island refuges is unlikely to secure the species from extinction. We identified large areas of potential habitat across the species’ former mainland range, but these are likely too distant from source populations for natural recolonisation. We propose that establishing new populations of forty‐spotted pardalotes via reintroduction is essential to secure the species and that this is best achieved while robust source populations still exist.     

Structural effects of hydration: studies of lysozyme by 13C solids NMR

13C-nmr spectra of lysozyme obtained at 50.3 MHz using both static and magic-angle-spinning-cross-polarization methods are reported at several water contents. The line widths and consequent resolution in the hydrated material is substantially improved over that in the lyophilized protein. The line narrowing is not commensurate with loss of a proton-carbon dipole-dipole coupling or dramatic changes in the relaxation parameters characterizing magnetization transfer from protons to carbon in the Hartmann-Hahn cross-polarization experiment. We interpret these data in terms of the water inducing a decrease in the distribution of local conformations sampled by the protein, although the magnitude of the conformational reorientations required to account for the data are not necessarily large nor do they imply a major unfolding of the protein on dehydration.     

Genetic heterogeneity among the founders of laboratory populations of Drosophila IV. Scutellar chaetae in different environments

The incidence of flies with more than four seutellar chaetae (additional chaetae) has been followed for up to 3 years in 4 lines at 15°C, 20°C, 25°C and 27.5°C derived from each of 3 strains, initially set up from single inseminated females of Drosophila melanogaster, collected in the wild single the same locality at the same time. Within each set of temperature lines, the incidence of additional chaetae was highest in one strain, intermediate in another strain, and lowest in the third. This shows that the differences between lines can be at least partly attributed to differences between the founder females of the three strains, although some divergence occurred between lines within strains in some cases. With respect to quantitative traits, the results indicate that in situations where new habitats are occupied by a small number of colonists, the nature of the founder female is possibly of greater importance than the different environments of the new habitats.Some of this work was supported by the Australian Research Grants Committee.