Long-term climatic stability drives accumulation and maintenance of divergent freshwater fish lineages in a temperate biodiversity hotspot.

Anthropogenic climate change is forecast to drive regional climate disruption and instability across the globe. These impacts are likely to be exacerbated within biodiversity hotspots, both due to the greater potential for species loss but also to the possibility that endemic lineages might not have experienced significant climatic variation in the past, limiting their evolutionary potential to respond to rapid climate change. We assessed the role of climatic stability on the accumulation and persistence of lineages in an obligate freshwater fish group endemic to the southwest Western Australia (SWWA) biodiversity hotspot. Using 19,426 genomic (ddRAD-seq) markers and species distribution modelling, we explored the phylogeographic history of western (Nannoperca vittata) and little (Nannoperca pygmaea) pygmy perches, assessing population divergence and phylogenetic relationships, delimiting species and estimating changes in species distributions from the Pliocene to 2100. We identified two deep phylogroups comprising three divergent clusters, which showed no historical connectivity since the Pliocene. We conservatively suggest these represent three isolated species with additional intraspecific structure within one widespread species. All lineages showed long-term patterns of isolation and persistence owing to climatic stability but with significant range contractions likely under future climate change. Our results highlighted the role of climatic stability in allowing the persistence of isolated lineages in the SWWA. This biodiversity hotspot is under compounding threat from ongoing climate change and habitat modification, which may further threaten previously undetected cryptic diversity across the region.

Monsoonal wet season influences the migration tendency of a catadromous fish (barramundi Lates calcarifer).

Many animals exhibit partial migration, which occurs when populations contain coexisting contingents of migratory and resident individuals. This individual-level variation in migration behaviour may drive differences in growth, age at maturity and survival. Therefore, partial migration is widely considered to play a key role in shaping population demography. Otolith chemistry and microstructural analysis were used to identify the environmental- and individual-specific factors that influence migratory behaviour in the facultatively catadromous barramundi (Lates calcarifer) at two distinct life history stages: firstly, as juveniles migrating upstream into fresh water; and secondly, as adults or sub-adults returning to the estuarine/marine spawning habitat. Monsoonal climate played an important role in determining the migration propensity of juveniles: individuals born in the driest year examined (weak monsoon) were more than twice as likely to undergo migration to freshwater than those born in the wettest (strong monsoon) year. In contrast, the ontogenetic timing of return migrations to the estuary by adults and sub-adults was highly variable and not strongly associated with the environmental parameters examined. We propose that scarce resources within saline natal habitats during lower rainfall years may provide an ecological incentive for juveniles to migrate upstream, whereas more abundant resources in higher rainfall years may promote resident life histories within estuaries. We conclude that inter-annual climatic variation, here evidenced by monsoonal strength, likely plays an important role in driving the persistence of diversified life histories within wild barramundi populations.

Effects of coastal development on sawfish movements and the need for marine animal crossing solutions.

Although human-made barriers to animal movement are ubiquitous across many types of ecosystems, the science behind these barriers and how to ameliorate their effects lags far behind in marine environments compared with terrestrial and freshwater realms. Using juvenile sawfish in an Australian nursery habitat as a model system, we aimed to assess the effects of a major anthropogenic development on the movement behavior of coastal species. We compared catch rates and movement behavior (via acoustic telemetry) of juvenile green sawfish (Pristis zijsron) before and after a major coastal structure was built in an important nursery habitat. Acoustic tracking and catch data showed that the development did not affect levels of sawfish recruitment in the nursery, but it did constrain movements of juveniles moving throughout the nursery, demonstrating the reluctance of shoreline-associated species to travel around large or unfamiliar coastal structures. Given the current lack of information on human-made movement barriers in the marine environment, these findings highlight the need for further research in this area, and we propose the development of and experimentation with marine animal crossings as an important area of emerging research.

Efectos del desarrollo costero sobre los movimientos del pez sierra y la necesidad de soluciones para el cruce de animales marinos Resumen Mientras que las barreras construidas por humanos que limitan el movimiento de animales son ubicuas en muchos tipos de ecosistemas, la ciencia que sustenta estas barreras y la reducción de sus impactos está muy retrasada en ambientes marinos en comparación con medios terrestres y dulceacuícolas. Utilizando peces sierra juveniles en un hábitat de vivero australiano como sistema modelo, intentamos evaluar los efectos de un importante desarrollo antropogénico sobre el comportamiento de especies costeras. Comparamos las tasas de captura y el comportamiento de movimiento (mediante telemetría acústica) de peces sierra verdes juveniles (Pristis zijsron) antes y después de que se construyera infraestructura costera en un importante hábitat de vivero. El seguimiento acústico y los datos de captura mostraron que el desarrollo no afectó los niveles de reclutamiento de pez sierra en el vivero, pero sí restringió los movimientos de los juveniles desplazándose por el vivero, lo cual demuestra la renuencia de las especies asociadas a la costa a viajar alrededor de estructuras costeras grandes o desconocidas. Dada la actual falta de información sobre las barreras de movimiento creadas por el hombre en el medio marino, estos hallazgos destacan la necesidad de realizar más investigaciones en esta campo, y proponemos el desarrollo y la experimentación con cruces para animales marinos como un área importante de investigación emergente.

Net design for selective control of the "plague minnow" Gambusia holbrooki that minimises impact on native Australian fishes.

Gambusia holbrooki is one of the world's most environmentally damaging introduced species, being notoriously difficult to control once established. A composite double-winged fyke net comprising four vertically stacked compartments was developed to determine the potential to control G. holbrooki, while reducing negative interactions of this aggressive species with small threatened fishes. The stacked fyke net captured three times as many G. holbrooki as a conventional fyke net while maintaining consistent catches of native fishes relative to that from a conventional fyke net, and detected species-specific vertical distributions. This stratified net design represents a valuable management option for controlling this agonistic species or for limiting antagonistic interactions between G. holbrooki and native species during typical fyke sampling of native ecosystems.

Divergent field metabolic rates highlight the challenges of increasing temperatures and energy limitation in aquatic ectotherms.

Environments where extreme temperatures and low productivity occur introduce energetically challenging circumstances that may be exacerbated by climate change. Despite the strong link between metabolism and temperature in ectotherms, there is a paucity of data regarding how the metabolic ecology of species affects growth and fitness under such circumstances. Here, we integrated data describing field metabolic rates and body condition of two sympatric species of ectotherms with divergent lifestyles, the benthic freshwater (or largetooth) sawfish (Pristis pristis) and the epipelagic bull shark (Carcharhinus leucas) occurring in the Fitzroy River, Western Australia, to test the implications of their differing metabolic ecologies for vulnerability to rising temperatures. Over a temperature range of 18-34 °C, sawfish had lower field metabolic rates (63-187 mg O2 kg-0.86 h-1) and lower temperature sensitivity of metabolic rates [activation energy (EA) = 0.35 eV] than bull sharks (187-506 mg O2 kg-0.86 h-1; EA = 0.48 eV). Both species lost body mass throughout the dry season, although bull sharks significantly more (0.17% mass loss day-1) than sawfish (0.07% mass loss day-1). Subsequent bioenergetics modelling showed that under future climate change scenarios, both species would reach potentially lethal levels of mass loss during dry season periods before the end of the century. These results suggest that ectotherms with low metabolic rates may be better suited to extreme environmental conditions, and that even small increases in temperature due to climate change could have substantial impacts on the ability of ectotherms to grow and survive in harsh conditions, including high temperatures and energy-limiting circumstances.

Respirometer in a box: development and use of a portable field respirometer for estimating oxygen consumption of large-bodied fishes.

This study developed a portable, low-cost field respirometer for measuring oxygen consumption rates of large-bodied fishes. The respirometer performed well in laboratory tests and was used to measure the oxygen consumption rates ( M ˙ O2 ) of bull sharks Carcharhinus leucas (mean: 249.21 ± 58.10 mg O2 kg-1 h-1 at 27.05°C). Interspecific comparisons and assessments of oxygen degradation curves indicated that the respirometer provided reliable measurements of M ˙ O2 . This system presents a field-based alternative to laboratory respirometers, opening opportunities for studies on species in remote localities, increasing the ability to validate physiological field studies.

Migration to freshwater increases growth rates in a facultatively catadromous tropical fish.

Diadromy is a form of migration where aquatic organisms undergo regular movements between fresh and marine waters for the purposes of feeding and reproduction. Despite having arisen in independent lineages of fish, gastropod molluscs and crustaceans, the evolutionary drivers of diadromous migration remain contentious. We test a key aspect of the 'productivity hypothesis', which proposes that diadromy arises in response to primary productivity differentials between marine and freshwater habitats. Otolith chemistry and biochronology data are analysed in a facultatively catadromous tropical fish (barramundi, Lates calcarifer) to determine the effect of freshwater residence on growth rates. Individuals that accessed freshwater grew ~ 25% faster on average than estuarine residents in the year following migration, suggesting that catadromy provides a potential fitness advantage over non-catadromous (marine/estuarine) life histories, as predicted by the productivity hypothesis. Although diadromous barramundi exhibited faster growth than non-diadromous fish, we suggest that the relative reproductive success of diadromous and non-diadromous contingents is likely to be strongly influenced by local environmental variability such as temporal differences in river discharge, and that this may facilitate the persistence of diverse life history strategies within populations.

Thermal performance responses in free-ranging elasmobranchs depend on habitat use and body size.

Temperature is one of the most influential drivers of physiological performance and behaviour in ectotherms, determining how these animals relate to their ecosystems and their ability to succeed in particular habitats. Here, we analysed the largest set of acceleration data compiled to date for elasmobranchs to examine the relationship between volitional activity and temperature in 252 individuals from 8 species. We calculated activation energies for the thermal performance response in each species and estimated optimum temperatures using an Arrhenius breakpoint analysis, subsequently fitting thermal performance curves to the activity data. Juveniles living in confined nursery habitats not only spent substantially more time above their optimum temperature and at the upper limits of their performance breadths compared to larger, less site-restricted animals, but also showed lower activation energies and broader performance curves. Species or life stages occupying confined habitats featured more generalist behavioural responses to temperature change, whereas wider ranging elasmobranchs were characterised by more specialist behavioural responses. The relationships between the estimated performance regimes and environmental temperature limits suggest that animals in confined habitats, including many juvenile elasmobranchs within nursery habitats, are likely to experience a reduction of performance under a warming climate, although their flatter thermal response will likely dampen this impact. The effect of warming on less site-restricted species is difficult to forecast since three of four species studied here did not reach their optimum temperature in the wild, although their specialist performance characteristics may indicate a more rapid decline should optimum temperatures be exceeded.

Evaluating the Dispersant Stabilization of Colloidal Suspensions from the Scaling Behavior of Gel Rheology and Adsorption Measurements.

Maintaining suspension stability by effective particle dispersion in systems with attractive interactions can be accomplished by the addition of dispersants that modify the interparticle potential to provide steric or electrostatic barriers against aggregation. The efficacy of such dispersants is typically considered simply by the modification of suspension rheological properties as a function of the overall added dispersant concentration. However, such considerations do little to reveal the molecular origin of differences in dispersant efficacy because they do not consider differences in surface activity. We combine measured adsorption isotherms with the rheological characterization of the elasticity of colloidal gels formed by particle aggregation to provide a more meaningful assessment of dispersant efficacy. The rheological data show that the dispersants are effective at reducing particle aggregation, whereas, from the adsorption isotherms, they differ considerably in their surface coverage at constant overall concentration. When compared at constant dispersant particle surface coverage, the gel rheology shows marked differences across the different dispersants, as opposed to comparisons at constant overall dispersant concentration in the suspensions. In particular, the power-law volume fraction scaling of gel elasticity at constant coverage reveals clear differences in the critical volume fraction for gel formation for the different dispersants. The most efficacious dispersant is that associated with the largest critical volume fraction for gel formation at a given surface coverage. This work demonstrates the utility of rheological investigations coupled with accurate determinations of surface coverage to better differentiate dispersant performance, which may improve efforts to engineer new dispersant molecules.

Themes, Theories, and Models.

Although theory building is often described as the ultimate goal of qualitative research, an examination of articles in Qualitative Health Research ( QHR) shows that themes are actually the typical format for reporting results. In addition, articles that rely on themes often present low-level theories in the form of models that connect these themes. Because models have received less attention than either themes or theories, this article concentrates on summarizing four different kinds of models: hierarchies, timelines, processes, and cycles. In each of these cases, it presents both a general illustration of such a model and a realistic example from a published article in QHR. It concludes with a call for greater recognition of the role that models play in capturing the results of qualitative research.

Effects Of treadmill training on hindlimb muscles of spinal cord-injured mice.

INTRODUCTION: Treadmill training is known to prevent muscle atrophy after spinal cord injury (SCI), but the training duration required to optimize recovery has not been investigated. METHODS: Hemisected mice were randomized to 3, 6, or 9 weeks of training or no training. Muscle fiber type composition and fiber cross-sectional area (CSA) of medial gastrocnemius (MG), soleus (SOL), and tibialis anterior (TA) were assessed using ATPase histochemistry. RESULTS: Muscle fiber type composition of SCI animals did not change with training. However, 9 weeks of training increased the CSA of type IIB and IIX fibers in TA and MG muscles. CONCLUSIONS: Nine weeks of training after incomplete SCI was effective in preventing atrophy of fast-twitch muscles, but there were limited effects on slow-twitch muscles and muscle fiber type composition. These data provide important evidence of the benefits of exercising paralyzed limbs after SCI. Muscle Nerve, 2016 Muscle Nerve 55: 232-242, 2017.

Mechanical challenges to freshwater residency in sharks and rays.

Major transitions between marine and freshwater habitats are relatively infrequent, primarily as a result of major physiological and ecological challenges. Few species of cartilaginous fish have evolved to occupy freshwater habitats. Current thought suggests that the metabolic physiology of sharks has remained a barrier to the diversification of this taxon in freshwater ecosystems. Here, we demonstrate that the physical properties of water provide an additional constraint for this species-rich group to occupy freshwater systems. Using hydromechanical modeling, we show that occurrence in fresh water results in a two- to three-fold increase in negative buoyancy for sharks and rays. This carries the energetic cost of lift production and results in increased buoyancy-dependent mechanical power requirements for swimming and increased optimal swim speeds. The primary source of buoyancy, the lipid-rich liver, offers only limited compensation for increased negative buoyancy as a result of decreasing water density; maintaining the same submerged weight would involve increasing the liver volume by very large amounts: 3- to 4-fold in scenarios where liver density is also reduced to currently observed minimal levels and 8-fold without any changes in liver density. The first data on body density from two species of elasmobranch occurring in freshwater (the bull shark Carcharhinus leucas, Müller and Henle 1839, and the largetooth sawfish Pristis pristis, Linnaeus 1758) support this hypothesis, showing similar liver sizes as marine forms but lower liver densities, but the greatest negative buoyancies of any elasmobranch studied to date. Our data suggest that the mechanical challenges associated with buoyancy control may have hampered the invasion of freshwater habitats in elasmobranchs, highlighting an additional key factor that may govern the predisposition of marine organisms to successfully establish in freshwater habitats.

From themes to hypotheses: following up with quantitative methods.

One important category of mixed-methods research designs consists of quantitative studies that follow up on qualitative research. In this case, the themes that serve as the results from the qualitative methods generate hypotheses for testing through the quantitative methods. That process requires operationalization to translate the concepts from the qualitative themes into quantitative variables. This article illustrates these procedures with examples that range from simple operationalization to the evaluation of complex models. It concludes with an argument for not only following up qualitative work with quantitative studies but also the reverse, and doing so by going beyond integrating methods within single projects to include broader mutual attention from qualitative and quantitative researchers who work in the same field.

Implications of climate change for potamodromous fishes.

There is little understanding of how climate change will impact potamodromous freshwater fishes. Since the mid 1970s, a decline in annual rainfall in south-western Australia (a globally recognized biodiversity hotspot) has resulted in the rivers of the region undergoing severe reductions in surface flows (ca. 50%). There is universal agreement amongst Global Climate Models that rainfall will continue to decline in this region. Limited data are available on the movement patterns of the endemic freshwater fishes of south-western Australia or on the relationship between their life histories and hydrology. We used this region as a model to determine how dramatic hydrological change may impact potamodromous freshwater fishes. Migration patterns of fishes in the largest river in south-western Australia were quantified over a 4 year period and were related to a number of key environmental variables including discharge, temperature, pH, conductivity and dissolved oxygen. Most of the endemic freshwater fishes were potamodromous, displaying lateral seasonal spawning migrations from the main channel into tributaries, and there were significant temporal differences in movement patterns between species. Using a model averaging approach, amount of discharge was clearly the best predictor of upstream and downstream movement for most species. Given past and projected reductions in surface flow and groundwater, the findings have major implications for future recruitment rates and population viabilities of potamodromous fishes. Freshwater ecosystems in drying climatic regions can only be managed effectively if such hydro-ecological relationships are considered. Proactive management and addressing existing anthropogenic stressors on aquatic ecosystems associated with the development of surface and groundwater resources and land use is required to increase the resistance and resilience of potamodromous fishes to ongoing flow reductions.

Patterns of cyanide antidote use since regulatory approval of hydroxocobalamin in the United States.

Sodium nitrite and sodium thiosulfate are common cyanide antidotes. Hydroxocobalamin was approved for use in the United States in 2006. Our objective was to determine the frequency of antidote use as reported to the US poison centers from 2005 to 2009 and describe which antidotes were used in critically ill cyanide toxic patients. We performed a retrospective review over 5 years (2005-2009) from 61 US poison centers. We identified all cyanide-exposed cases that received a cyanide antidote. Variables collected included demographics, gastric decontamination, antidote used, predefined serious clinical effects (hypotension, cardiac arrest, respiratory arrest, and coma), and predefined serious therapies (cardiopulmonary resuscitation, vasopressors, atropine, anticonvulsant, antidysrhythmic, and intubation/ventilation). One trained abstractor abstracted each chart to a standardized electronic form. Another investigator audited 20% of the charts. Kappa values were calculated. One hundred sixty-five exposures were identified. Mean age was 42 years (range, 3-93 years). Seventy-one percent were male. Exposures were 27% ingestion and 53% inhalation. Thirty-two percent of the ingestions were suicide attempts. Twenty percent (32 of 157) of all cases died. Over all years reported, hydroxocobalamin was administered to 29% (45 of 157) of patients, sodium nitrite to 25%, and sodium thiosulfate to 46%. Hydroxocobalamin use increased from 24% to 54% from 2007 to 2009, respectively (P = 0.024). Sodium thiosulfate use decreased from 73% to 31% (P = 0.002) and sodium nitrite use decreased from 26% to 14% (P = 0.39). The proportion of cases with serious clinical effects that received hydroxocobalamin increased each year, and the proportion that received other antidotes decreased. Hydroxocobalamin was also administered more often in cases that required serious therapies and increased each year. Hydroxocobalamin use for cyanide toxicity increased each year as reported to the US poison centers. Reported use of sodium thiosulfate and sodium nitrite decreased over the same years. In addition, hydroxocobalamin was used more often each year in critically ill cyanide toxic patients than were sodium nitrite or sodium thiosulfate.

Cryptic diversity within two widespread diadromous freshwater fishes (Teleostei: Galaxiidae).

Identification of taxonomically cryptic species is essential for the effective conservation of biodiversity. Freshwater-limited organisms tend to be genetically isolated by drainage boundaries, and thus may be expected to show substantial cryptic phylogenetic and taxonomic diversity. By comparison, populations of diadromous taxa, that migrate between freshwater and marine environments, are expected to show less genetic differentiation. Here we test for cryptic diversity in Australasian populations (both diadromous and non-diadromous) of two widespread Southern Hemisphere fish species, Galaxias brevipinnis and Galaxias maculatus. Both mtDNA and nuclear markers reveal putative cryptic species within these taxa. The substantial diversity detected within G. brevipinnis may be explained by its strong climbing ability which allows it to form isolated inland populations. In island populations, G. brevipinnis similarly show deeper genetic divergence than those of G. maculatus, which may be explained by the greater abundance of G. maculatus larvae in the sea allowing more ongoing dispersal. Our study highlights that even widespread, 'high-dispersal' species can harbour substantial cryptic diversity and therefore warrant increased taxonomic and conservation attention.

Ectoparasites of the Critically Endangered green sawfish Pristis zijsron and sympatric elasmobranchs in Western Australia.

This study reports the metazoan ectoparasite fauna of juvenile Critically Endangered green sawfish, Pristis zijsron, and sympatric elasmobranchs in Western Australia. Five parasite taxa were found on 76 screened P. zijsron: Caligus furcisetifer (Copepoda: Caligidae), Dermopristis pterophila (Monogenea: Microbothriidae), Branchellion plicobranchus and Stibarobdella macrothela (Hirudinea: Piscicolidae), and praniza larvae of an unidentified gnathiid isopod. Only C. furcisetifer and D. pterophila were common, exhibiting discrepant site-specificity, with C. furcisetifer occurring mostly on the head and rostrum, and D. pterophila around the pectoral and pelvic fins. Intensity of infection for C. furcisetifer and D. pterophila increased with host total length and was influenced by host sex, but in opposite directions; intensity of C. furcisetifer was greater on female P. zijsron, whereas intensity of D. pterophila was greater on males. In the Ashburton River, likelihood of infection for C. furcisetifer and D. pterophila on P. zijsron increased with time since substantial freshwater discharge events, suggesting decreased salinity impacts both taxa. In addition to P. zijsron, five other sympatric elasmobranch species were opportunistically screened for ectoparasites in the study area: the giant shovelnose ray, Glaucostegus typus, the eyebrow wedgefish, Rhynchobatus palpebratus, the nervous shark, Carcharhinus cautus, the lemon shark, Negaprion acutidens, and the graceful shark, Carcharhinus amblyrhynchoides. Caligus furcisetifer was found on R. palpebratus; no other parasites of P. zijsron were found on other sympatric elasmobranch species. Conversely, Perissopus dentatus (Copepoda: Pandaridae) was found on all three carcharhinids but not on batoid rays (P. zijsron, G. typus or R. palpebratus).

Developing the Open Psychedelic Evaluation Nexus consensus measures for assessment of supervised psilocybin services: An e-Delphi study.

BACKGROUND: Voter initiatives in Oregon and Colorado authorize legal frameworks for supervised psilocybin services, but no measures monitor safety or outcomes. AIMS: To develop core measures of best practices. METHODS: A three-phase e-Delphi process recruited 36 experts with 5 or more years' experience facilitating psilocybin experiences in various contexts (e.g., ceremonial settings, indigenous practices, clinical trials), or other pertinent psilocybin expertise. Phase I, an on-line survey with qualitative, open-ended text responses, generated potential measures to assess processes, outcomes, and structure reflecting high quality psilocybin services. In Phase II, experts used seven-point Likert scales to rate the importance and feasibility of the Phase I measures. Measures were priority ranked. Qualitative interviews and analysis in Phase III refined top-rated measures. RESULTS: Experts (n = 36; 53% female; 71% white; 56% heterosexual) reported currently providing psilocybin services (64%) for a mean of 15.2 [SD 13.1] years, experience with indigenous psychedelic practices (67%), and/or conducting clinical trials (36%). Thematic analysis of Phase I responses yielded 55 candidate process measures (e.g., preparatory hours with client, total dose of psilocybin administered, documentation of touch/sexual boundaries), outcome measures (e.g., adverse events, well-being, anxiety/depression symptoms), and structure measures (e.g., facilitator training in trauma informed care, referral capacity for medical/psychiatric issues). In Phase II and III, experts prioritized a core set of 11 process, 11 outcome, and 17 structure measures that balanced importance and feasibility. CONCLUSION: Service providers and policy makers should consider standardizing core measures developed in this study to monitor the safety, quality, and outcomes of community-based psilocybin services.

Ontogenetic development of intestinal length and relationships to diet in an Australasian fish family (Terapontidae).

BACKGROUND: One of the most widely accepted ecomorphological relationships in vertebrates is the negative correlation between intestinal length and proportion of animal prey in diet. While many fish groups exhibit this general pattern, other clades demonstrate minimal, and in some cases contrasting, associations between diet and intestinal length. Moreover, this relationship and its evolutionary derivation have received little attention from a phylogenetic perspective. This study documents the phylogenetic development of intestinal length variability, and resultant correlation with dietary habits, within a molecular phylogeny of 28 species of terapontid fishes. The Terapontidae (grunters), an ancestrally euryhaline-marine group, is the most trophically diverse of Australia's freshwater fish families, with widespread shifts away from animal-prey-dominated diets occurring since their invasion of fresh waters. RESULTS: Description of ontogenetic development of intestinal complexity of terapontid fishes, in combination with ancestral character state reconstruction, demonstrated that complex intestinal looping (convolution) has evolved independently on multiple occasions within the family. This modification of ontogenetic development drives much of the associated interspecific variability in intestinal length evident in terapontids. Phylogenetically informed comparative analyses (phylogenetic independent contrasts) showed that the interspecific differences in intestinal length resulting from these ontogenetic developmental mechanisms explained ~65% of the variability in the proportion of animal material in terapontid diets. CONCLUSIONS: The ontogenetic development of intestinal complexity appears to represent an important functional innovation underlying the extensive trophic differentiation seen in Australia's freshwater terapontids, specifically facilitating the pronounced shifts away from carnivorous (including invertebrates and vertebrates) diets evident across the family. The capacity to modify intestinal morphology and physiology may also be an important facilitator of trophic diversification during other phyletic radiations.

Introducing dyadic interviews as a method for collecting qualitative data.

In dyadic interviews, two participants interact in response to open-ended research questions. There are few precedents for using dyadic interviews as a technique for qualitative research. We introduce this method largely in comparison to focus groups, because both represent forms of interactive interviewing. We do not, however, view dyadic interviews as miniature focus groups, and treat them as generating their own opportunities and issues. To illustrate the nature of dyadic interviewing, we present summaries of three studies using this method. In the first study, we used dyadic interviews and photovoice techniques to examine experiences of people with early-stage dementia. In the second study, we explored the experiences of staff who provided services to elderly housing residents. In the third study, we examined barriers and facilitators to substance abuse treatment among Asian Americans and Pacific Islanders in Hawaii. We conclude with a discussion of directions for future research using dyadic interviews.