Is water extraction a threat to insect populations in intermittently-flowing streams?

Stream insects use a variety of refuges to survive drought that vary in their vulnerability to water extraction. We surveyed drought refuges in 16 ephemeral streams with different flow regimes. Perennial sections were the most important drought refuge, but are the most likely to disappear when water is extracted.

Variation in gametophyte dominance in populations of Chondrus verrucosus (Gigartinaceae, Rhodophyta)

We describe the abundance, including spatial and temporal variability, of phases of the isomorphic Chondrus verrucosus Mikami from Japan. Chondrus verrucosus occurred in a dense (∼90% cover) and temporally stable bed on a small, isolated rocky outcrop (Oyakoiwa) in Shizuoka Prefecture. Small vegetative fronds were always much more abundant than large vegetative and fertile fronds over the spring to late summer periods in 1999 and 2000. Over the same period, fertile carposporophytic fronds were generally more abundant than fertile tetrasporophytic fronds, and fertile male fronds appeared infrequently at low densities. Using the resorcinol-acetal test, we determined the proportion of gametophytes and tetrasporophytes in three populations of C. verrucosus: Oyakoiwa and Noroshi (Shizuoka) in the summers of 1999 and 2000 and Kamehana Point (Miyagi) in autumn 2000. All populations had a significantly higher proportion of gametophytes than tetrasporophytes in both years, although gametophytic proportions were lower at Noroshi (∼70%) than at Oyakoiwa (∼80%) and Kamehana Point (∼97%). However, examination of all isolated individuals sampled on Noroshi showed equal proportions of each phase in 1999, but gametophyte dominance (74%) in 2000. Differences in dispersal and spore production between phases are discussed as mechanisms potentially contributing to variation in gametophyte dominance.

Barriers to cross-fertilization between populations of a widely dispersed Polychaete species are unlikely to have arisen through gametic compatibility arms-races

Although there are theoretical reasons to suspect that gametic incompatibility may develop readily among populations of broadcast spawning marine invertebrates, there have been very few studies documenting geographic patterns of interpopulation incompatibility for any species. To address this we determined how successfully individuals of the intertidal serpulid polychaete, Galeolaria caespitosa, can cross-fertilize within and among populations from across temperate Australia. Fertilization assays revealed asymmetrical differences between very distantly located populations from different coasts, with near-complete incompatibility between eggs from Sydney with sperm from Adelaide, but the reverse cross (Adelaide eggs, Sydney sperm) was reasonably compatible. Although that pattern was congruent with a clear difference in Cytochrome B sequences between worms on the south and east coasts of Australia, we also detected some indication of interpopulation incompatibility within the genetic grouping on east coast, between two populations separated by only 220 km. We then assessed whether commonly proposed gametic compatibility arms-races could account for these patterns. Our results suggest reduced gametic compatibility may reduce a female's maximum fertilization potential, resulting in a cost to this potential mechanism for reducing polyspermy. Consequently, the apparently rapid development of reproductive barriers here seems unlikely to have been driven by arms-races involving sexual conflict over fertilization rate.

Factors influencing population dynamics in island and mainland populations of the Swamp Antechinus (Antechinus minimus)

Simultaneously analysing demographic processes of small mammals living in different ecological contexts may help to understand mechanisms that influence the growth and decline of these populations. The size and demography of swamp antechinus (Antechinus minimus) populations located in a coastal mainland habitat and on a small offshore island in south-eastern Australia were investigated. Large demographic differences occurred between the two ecosystems, with the island population density often 100 times greater than that on the mainland. The swamp antechinus in the mainland habitat was influenced by extrinsic climatic forces, with juvenile recruitment, individual body mass and overall population size being affected by rainfall, a factor likely to influence food availability for the species. However, the island population did not appear to be affected by drought to the same degree where allochthonous marine nutrient inputs may have offset any drought-induced reduction in primary production. Significantly greater juvenile recruitment in the island habitats combined with restricted emigration and potentially reduced predation and interspecific competition are likely to be responsible for the high population densities on the island. Although island populations appear robust, future conservation efforts should focus on mainland populations given the genetic deficiencies in the island populations.

The application of the transtheoretical model to offender populations : some critical issues

Purpose : Over the past two decades, the transtheoretical model (TTM) of change has become perhaps the most widely used model of behaviour change in the treatment of addictive and/or problem behaviours. More recently, the stages of change component of the TTM has been adopted for use in forensic settings. This paper aims to review the application of the TTM model to offender populations.

Arguments : The application of the TTM to offenders raises a number of issues regarding the process of behaviour change for offenders attending treatment programmes. It is argued that while the TTM has been designed to account for high frequency behaviour (e.g. smoking, alcohol misuse), offending behaviour may be less frequent and the process of change less cyclical. Moreover, it is suggested that the most important issue in a treatment context is the proper integration of the TTM constructs. There have been few empirical tests of this aspect of the model.

Conclusion : While the TTM may have some value in explaining how rehabilitation programmes help offenders to change their behaviour, the stages of change construct is, by itself, unlikely to adequately explain the process by which offenders desist from offending.

Microsatellites revealed no genetic differentiation between hatchery and contemporary wild populations of striped catfish, Pangasianodon hypophthalmus (Sauvage 1878) in Vietnam

Aquaculture of the striped catfish, Pangasianodon hypophthalmus (Sauvage 1878), in Vietnam has become one of the fastest growing primary food production sectors in the world. Although a demand on quantity of fingerlings is currently reached, it is likely that the long term quality of the stocks may be uncertain due to lacking of genetic broodstock management measures. The present study employed five microsatellite loci to investigate levels of genetic variation of the stripped catfish of the current wild stocks as well as of the selected hatcheries in Vietnam. The study included four hatchery populations and two wild populations spawned in 2005 in the Mekong and Bassac Rivers, and one wild population (spawned in 2006) in the Bassac River. The results showed no genetic differentiation among populations as revealed by F_ST and a model-based clustering method. AMOVA also showed no genetic differentiation between pooled wild and pooled hatchery populations while variation within groups was significant. Genetic variation of wild (mean number of alleles per locus, A = 4.80–6.20; allelic richness, A_r = 4.54–5.06; mean effective number of alleles per locus, A_e = 2.86–3.20; observed heterozygosity, H_o = 0.62–0.65; expected heterozygosity, H_e = 0.62–0.64) and hatchery populations (A = 4.60–5.20; A^_r = 4.10–4.83; A_e = 2.80–3.11; H_o = 0.61–0.66; H_e = 0.61–0.64) were not statistically different. There were no evidences for recent genetic bottleneck in all populations. Therefore it is implied that the hatchery stocks of striped catfish in Vietnam were founded from sufficient numbers of brooders and current population size is large. The domestication process is in an early stage.

Asexual reproduction does not produce clonal populations of the brooding coral Pocillopora damicornis on the Great Barrier Reef, Australia

We have investigated the relationship between genotypic diversity, the mode of production of brooded larvae and disturbance in a range of reef habitats, in order to resolve the disparity between the reproductive mode and population structure reported for the brooding coral Pocillopora damicornis. Within 14 sites across six habitats, the ratio of the observed (G o) to the expected (G e) genotypic diversity ranged from 69 to 100% of that expected for random mating. At three other sites in two habitats the G o /G e ranged from 35 to 53%. Two of these sites were recently bleached, suggesting that asexual recruitment may be favoured after disturbance. Nevertheless, our data suggest that brooded larvae, from each of five habitats surveyed, were asexually produced. While clonal recruitment may be important in disturbed habitats, the lack of clonality detected, both in this and earlier surveys of 40 other sites, implies that a disturbance is normally insufficient to explain this species’ continued investment in clonal reproduction.

Development of molecular techniques for the genetic analysis of abalone populations

Three DNA techniques: random amplified polymorphic DNA (RAPD), minisatellite, and microsatellite analyses, were developed for use in abalone population genetic structure studies. The techniques were assessed using sample sets of blacklip and greenlip abalone. The study identifies a potential for the application of these DNA markers in abalone fisheries management, but microsatellites are the recommended method for future studies.

Malingering and denial among forensic populations

The issue of malingering and denial is significantly important for clinicians working with forensic clients who are mandated to attend assessments and treatments, or in respect to pre-sentence reports. Four case studies are presented. Explanatory models of defensiveness and malingering are based upon the clients' motivations and include pathogenic, criminalogical and adaptional models.

Resource partitioning in sympatric populations of Red-necked Wallabies and Black Wallabies

Examines the potential for competition to occur between the Red-necked Wallaby and the Black Wallaby by examining the extent of overlap in their dietary preferences and in their utilisation of habitat at different times of the day and year. Significant separation occured between species to facilitate coexistence.

Comparative ecology of island and mainland swamp antechinus populations

The demography, reproduction and behaviour of the swamp antechinus, a small carnivorous marsupial, were compared in island and mainland populations. Divergent demography and behaviour occurred between populations, with island animals benefiting from increased productivity caused by nesting seabirds. However, evolutionary divergence in life-history and morphology, which occur in island rodent populations, were not recorded.

Comparison of life-history characteristics of island and mainland populations of the swamp antechinus

The reproductive ecology of the swamp antechinus Antechinus minimus, a small dasyurid (Dasyuridae) marsupial with obligate male semelparity, was investigated in populations inhabiting the mainland coast and on a nearby offshore island in south-eastern Australia. The size and sex ratios of litters, individual body mass and size, timing of births and female longevity were determined from live-trapped animals. The island population had significantly smaller litter sizes and greater adult body mass in comparison with the mainland population. This is consistent with features of the ‘island syndrome’, which predicts directional selection for these traits in high-density populations with reduced extrinsic mortality. However, inter-annual variability in litter sizes in the island population suggests that litter size is more responsive to fluctuating local conditions, such as population density, which is likely to affect food availability, rather than directional genetic changes. In contrast with other antechinus species, biased sex ratios were not evident. In addition, large variations of the timing of births were estimated at both sites and these appear to be related to seasonal conditions such as autumn rainfall and female body mass before mating.