Use of terrestrial habitats by burrow-nesting seabirds in south-eastern Australia

The size and growth of seabird populations are believed to be regulated, in part, by the availability and quality of suitable breeding habitat. Global climate change is predicted to affect coastal habitats and may, therefore, have important consequences for the terrestrial breeding habitat of seabirds and hence seabird populations. The present study assessed use of breeding habitat in the four most abundant species of seabird breeding in south-eastern Australia using a generalised additive mixed-modelling approach. Habitat characteristics were measured on 13 islands in winter and summer, 2008-11. Burrows of the four species were associated with one or more habitat parameters, potentially explained by predator avoidance, physical requirements and possibly by interspecific competition. Whereas the habitat characteristics used by each species showed broad interspecific overlap, there was strong divergence, and the four species typically occupied different nesting sites within breeding areas. Information on the proportion of available habitat used and the influence of breeding habitat on reproductive success would enhance current understanding of what constitutes optimal breeding habitat as well as the role of interspecific competition in this assemblage of seabirds.

Seasonal- and sex-specific correlations between dispersal and exploratory behaviour in the great tit

While the importance of personality in explaining individual dispersal strategies is increasingly recognized, limited information is still available on how patterns of personality-dependent dispersal may develop, hampering our understanding of the ecological significance of behavioural dispersal syndromes. Here, we examine the relative importance of personality at different stages of dispersal in the great tit, by analysing the sex-specific relationship between exploratory behaviour (EB; quantified in a novel environment) and dispersal distances in different seasons over the course of the first year of life (summer, autumn, winter, and until the first breeding attempt). In females, we found that EB was an important predictor of dispersal distances in summer and autumn, but only a weak to moderate correlation remained for females captured in winter or for natal dispersal distances based on first breeding records. We obtained a contrasting pattern at the population level, whereby male (but not female) immigrants captured in summer and autumn had higher EB scores than locally born birds, while this was not the case in birds captured in winter and those recruited as breeders into the population. In addition to providing further evidence for the existence of a behaviour dispersal syndrome in birds, our results show that correlations between EB and dispersal appear strongest at the early stages of the dispersal process, rather than being developed gradually. These findings show the importance of analysing the effect of phenotypic attributes on dispersal across different stages of the dispersal phenomenon and in each sex separately.

Nonmarket valuation in developing countries: Incorporating labour contributions in environmental benefits estimates

There are limitations associated with the application of nonmarket valuation techniques, including choice experiments, in subsistence economies. In part, this is due to the concern that using money as a mode of contribution may not capture the potential contribution of low-income households. To address this limitation, respondents in this study were provided with the option of contributing towards the management of invasive plants in labour terms if they were unwilling to contribute in monetary terms. The results show that the existing practice of using dollar values to estimate willingness to contribute may disproportionately exclude the concerns of some groups within the community. The analysis also indicates that allowing respondents to express their willingness to contribute in labour increases their participation in environmental decision-making processes and hence increases the estimated value of forest ecosystem services. This study contributes to the limited empirical literature on the development of nonmarket valuation surveys, particularly choice experiments, in low-income countries in general and rural areas in particular. © 2014 Australian Agricultural and Resource Economics Society Inc.

Challenges and advances in the heterologous expression of cellulolytic enzymes: a review

Second generation biofuel development is increasingly reliant on the recombinant expression of cellulases. Designing or identifying successful expression systems is thus of preeminent importance to industrial progress in the field. Recombinant production of cellulases has been performed using a wide range of expression systems in bacteria, yeasts and plants. In a number of these systems, particularly when using bacteria and plants, significant challenges have been experienced in expressing full-length proteins or proteins at high yield. Further difficulties have been encountered in designing recombinant systems for surface-display of cellulases and for use in consolidated bioprocessing in bacteria and yeast. For establishing cellulase expression in plants, various strategies are utilized to overcome problems, such as the auto-hydrolysis of developing plant cell walls. In this review, we investigate the major challenges, as well as the major advances made to date in the recombinant expression of cellulases across the commonly used bacterial, plant and yeast systems. We review some of the critical aspects to be considered for industrial-scale cellulase production.

Sexual niche segregation and gender-specific individual specialisation in a highly dimorphic marine mammal

While sexual segregation is expected in highly dimorphic species, the local environment is a major factor driving the degree of resource partitioning within a population. Sexual and individual niche segregation was investigated in the Australian fur seal (Arctocephalus pusillus doriferus), which is a benthic foraging species restricted to the shallow continental shelf region of south-eastern Australia. Tracking data and the isotopic values of plasma, red blood cells and whiskers were combined to document spatial and dietary niche segregation throughout the year. Tracking data indicated that, in winter, males and females overlapped in their foraging habitat. All individuals stayed within central Bass Strait, relatively close (< 220 km) to the breeding colony. Accordingly, both genders exhibited similar plasma and red cell δ13C values. However, males exhibited greater δ13C intra-individual variation along the length of their whisker than females. This suggests that males exploited a greater diversity of foraging habitats throughout the year than their female counterparts, which are restricted in their foraging grounds by the need to regularly return to the breeding colony to suckle their pup. The degree of dietary sexual segregation was also surprisingly low, both sexes exhibiting a great overlap in their δ15N values. Yet, males displayed higher δ15N values than females, suggesting they fed upon a higher proportion of higher trophic level prey. Given that males and females exploit different resources (mainly foraging habitats), the degree of individual specialisation might differ between the sexes. Higher degrees of individual specialisation would be expected in males which exploit a greater range of resources. However, comparable levels of inter-individual variation in δ15N whisker values were found in the sampled males and females, and, surprisingly, all males exhibited similar seasonal and inter-annual variation in their δ13C whisker values, suggesting they all followed the same general dispersion pattern throughout the year.