Evolutionary Significance and Conservation Implications of Vocal Dialects in North Island Kōkako (Callaeas wilsoni)

Kōkako (Callaeas wilsoni) are endangered, duetting songbirds endemic to New Zealand and are confined to a small number of managed mainland reserves and offshore islands. Each fragmented population exhibits distinctive vocal traditions. Conservation of the species is centred on intensive site management of introduced mammalian predators – the current leading cause of kōkako population decline – followed by re-establishment of populations through translocation. Translocated populations are often sourced from multiple areas, leading to an artificially created scenario of secondary contact between behaviourally diverged populations. I studied the consequences of kōkako song traditions, and the effect of population-specific behaviours on conservation of the species. During a transfer of 20 birds from two distinct "song neighbourhoods" (c. 25% between-neighbourhood phrase sharing), I explored the utility of neighbourhood specific acoustic playback as a conservation tool in preventing excessive post-release dispersal. I found that birds dispersed less far than predicted by a random walk model, yet were no more attracted to same- than different-neighbourhood song playback. These results suggested that while playback appeared to reduce dispersal, this effect was not driven by neighbourhood-specific song. Following release, kōkako also used the available habitat disproportionately, preferring to remain in the short term, and to establish breeding territories within a forest type similar to that where they were caught. The vocal differences I detected between the neighbourhoods at the source sites were also insufficient to promote assortative mating following release. The findings of this experiment confirmed that neighbourhood-scale song variation does not act as a barrier to gene flow, or inhibit post-translocation population establishment. To assess whether more distinct vocal differences between populations (c. 5% between-population phrase sharing) represent more salient signals to kōkako, I performed reciprocal stereo playback experiments in two populations frequently used as translocation source sites. In one experiment I tested for discrimination between local and foreign dialect duets and found that pairs responded vocally to local duets with less delay, and produced more song phrases, with a lower diversity, compared to playback of foreign duets. This suggested that local song represented more of a threat to pairs than unfamiliar song. In a second experiment I presented pairs with two types of synthesised local-foreign mixed-dialect duets; each stimulus differed depending on the sex of the local duet stimulus component. I found that pairs responded with equal overall strength to both stimuli, and did so in a qualitatively similar way to pure local duets. As pairs did not discriminate between these stimuli, this indicates that if mixed-dialect pairs form, they should be able to effectively communicate with, and defend against territorial intruders. From an evolutionary perspective this further suggests that dialectal differences might not prevent gene flow in kōkako if pair formation between dialects can occur. Importantly, these findings also suggest that animals translocated for conservation purposes need not necessarily exhibit homogeneous cultures to acquire and defend resources. Sexual selection leading to positive assortative mating based on song dialect may act as an isolating barrier to gene flow, thus promoting speciation. From a conservation perspective this process could be problematic by hindering population establishment following translocation of a small number of individuals from multiple sources. To assess this tendency in kōkako, I harnessed an existing 18-year data set from reports prepared by the New Zealand Department of Conservation documenting multi-source translocations to six sites from 11 source populations. Based on these reports, in each breeding season at each site I compiled a list of the possible same- and mixed-dialect pairs that could have formed, which I then compared to the actual pairs in each season. In doing so, I statistically confirmed that, following release, kōkako pairs form assortatively based on dialect more often than expected by chance. However, mixed-dialect pairs did form in low numbers at two sites, either when an existing "core" population was present at the time of translocation, or following the release of a captive-reared sub-adult bird with potentially plastic song. These results suggest that sufficiently large differences in a sexually selected behavioural trait, such as song, can inhibit gene flow between populations. Taken together, my findings suggest that vocal variation among fragmented, allopatric populations may influence a species' cultural and genetic history, and could affect the success of conservation strategies. However, as kōkako pairs can form across dialects, and postnatal dispersal sometimes occurs between areas with different song traditions, complete genetic isolation of populations is unlikely to occur. Further research on the timing of song-learning in kōkako, dispersal patterns, and vocal plasticity in territorial adults will greatly advance our knowledge base and shed light on the function and conservation implications of song dialects in kōkako

The form and function of coordinated vocal signalling in a cooperatively breeding Neotropical songbird, the Rufous-naped Wren ( Campylorhynchus rufinucha)

Coordinated vocal signals produced by birds, such as duets and choruses, present a compelling opportunity to investigate the adaptive significance of cooperation and conflict-based behaviours. I studied the form and function of coordinated vocal signals in cooperatively breeding Neotropical Rufous-naped Wrens (Campylorhynchus rufinucha). I examined variation in daily and seasonal vocal output and found that solo and duet songs peak at dawn and decrease thereafter, and that solo song rate, but not duet or chorus song rate, varied across breeding stages. Both sexes have song repertoires, and song sharing decreases with distance between territorial groups. To examine the function of coordinated vocalizations, I played back solos, duets, and choruses to territorial birds to represent varying degrees of threat. Groups responded strongly and similarly to all playback treatments. This study suggests that song may be an important indicator of group identity and that coordinated vocalizations function in cooperative territory defence

Shear Bond Strength Comparison between Two Orthodontic Adhesives and Self-Ligating and Conventional Brackets

Objective: To evaluate and compare the shear bond strengths of two adhesives using two types of brackets: a conventional and a self-ligating bracket system. Materials and Methods: Sixty extracted human premolars were collected. The premolars were randomly divided into three groups of 20 teeth. All three groups were direct bonded. Groups 1 and 2 used light-cured adhesive and primer (Transbond XT) with a conventional (Orthos) and a self-ligating bracket (Damon 2), respectively. Group 3 used a light-cured primer (Orthosolo) and a light-cured adhesive (Blūgloo) with a self-ligating bracket (Damon 2). The specimens were stored in distilled water at 37°C for 40 ± 2 hours, after which they were debonded and inspected for Adhesive Remnant Index (ARI) scoring. Results: The mean shear bond strength was 15.2 MPa for group 1, 23.2 MPa for group 2, and 24.8 MPa for group 3. A one-way analysis of variance and post hoc Tukey test showed significant differences in bond strength (P \u3c .001) between group 1 and groups 2 and 3 but no significant difference (P \u3e .05) between groups 2 and 3. A Weibull analysis demonstrated that all three groups provided sufficient bond strength with over 90% survival rate at normal masticatory and orthodontic force levels. A Kruskal-Wallis test showed no significant difference (P \u3e .05) in ARI scores among all three groups. Conclusions: All three groups demonstrated clinically acceptable bond strength. The Damon 2 self-ligating bracket exhibited satisfactory in vitro bond strength with both adhesive systems used

Soluble tau species, not neurofibrillary aggregates, disrupt neural system integration in a tau transgenic model

Neurofibrillary tangles are a feature of Alzheimer disease and other tauopathies, and while they are generally believed to be markers of neuronal pathology, there is little evidence evaluating whether tangles directly impact neuronal function. To investigate the response of cells in hippocampal circuits to complex behavioral stimuli, we used an environmental enrichment paradigm to induce expression of an immediate-early gene, Arc, in the rTg4510 mouse model of tauopathy. These mice reversibly overexpress P301L tau and exhibit substantial neurofibrillary tangle deposition, neuronal loss, and memory deficits. Employing fluorescent in situ hybridization to detect Arc mRNA, we found that rTg4510 mice have impaired hippocampal Arc expression both without stimulation and in response to environmental enrichment; this likely reflects the combination of functional impairments of existing neurons and loss of neurons. However, tangle-bearing cells were at least as likely as non-tangle-bearing neurons to exhibit Arc expression in response to enrichment. Transgene suppression with doxycycline for 6 weeks resulted in increased percentages of Arc-positive cells in rTg4510 brains compared to untreated transgenics, restoring enrichment-induced Arc mRNA levels to that of wild-type controls despite the continued presence of neurofibrillary pathology. We interpret these data to indicate that soluble tau contributes to impairment of hippocampal function, while tangles do not preclude neurons from responding in a functional circuit

Galvanic Corrosion between Various Combinations of Orthodontic Brackets and Archwires

Introduction: The purpose of this study was to compare galvanic currents generated by different combinations of commonly used brackets and archwires. Methods: As-received stainless steel, nickel-titanium, and betatitanium wires were coupled to stainless steel and titanium brackets in an artificial saliva medium. The galvanic current and amount of charge transferred for each pair were monitored with a zero resistance ammeter for 10 hours. Results: Two-way analysis of variance (ANOVA) showed a significant difference in charge and galvanic currents when factored for type of bracket (P\0.001), but no significant difference between them when factored by type of wire (P .0.05). Specifically, a brazed stainless steel bracket was significantly greater in charge transferred and 10-hour galvanic current than metal injection molded stainless steel and titanium brackets (P\0.001), which were not different from each other (P .0.05). Conclusions: The method of bracket manufacturing might be of equal or more relevance to galvanic corrosion susceptibility than bracket composition

Globular Cluster Systems in Brightest Cluster Galaxies: Bimodal Metallicity Distributions and the Nature of the High-Luminosity Clusters

We present new (B,I) photometry for the globular cluster systems in eight Brightest Cluster Galaxies (BCGs), obtained with the ACS/WFC camera on the Hubble Space Telescope. In the very rich cluster systems that reside within these giant galaxies, we find that all have strongly bimodal color distributions All the BCGs show population gradients, with much higher relative numbers of red clusters within 5 kpc of their centers, consistent with their having formed at later times than the blue, metal-poor population. A striking new feature of the color distributions emerging from our data is that for the brightest clusters (M_I < -10.5) the color distribution becomes broad and less obviously bimodal. we suggest that it may be a characteristic of many BCGs. Furthermore, the blue (metal-poor) clusters become progressively redder with increasing luminosity, following a mass/metallicity scaling relation Z ~ M^0.55. We argue that these GCS characteristics are consistent with a hierarchical-merging formation picture in which the metal-poor clusters formed in protogalactic clouds or dense starburst complexes with gas masses in the range 10^7 - 10^10 M_Sun, but where the more massive clusters on average formed in bigger clouds with deeper potential wells where more pre-enrichment could occur.Comment: 48 pages, 24 Figures, PDF, Submitted to Astrophys.J. and refereed. For complete pdf file with better figures, see: http://physwww.mcmaster.ca/%7Eharris/Preprints.htm

Agouti C57BL/6N embryonic stem cells for mouse genetic resources.

We report the characterization of a highly germline competent C57BL/6N mouse embryonic stem cell line, JM8. To simplify breeding schemes, the dominant agouti coat color gene was restored in JM8 cells by targeted repair of the C57BL/6 nonagouti mutation. These cells provide a robust foundation for large-scale mouse knockout programs that aim to provide a public resource of targeted mutations in the C57BL/6 genetic background

Game Change: What Have We Learned? Pt. 1

Who We Are, What We Do, Where Are We Going Brookings Mountain West is a partnership between UNLV and the Washington, D.C.-based Brookings Institution. Goals and Objectives Create high-quality, independent, impactful programs, publications, and activities that address issues of critical importance to greater Las Vegas and the Intermountain West region. Serve as a platform to bring ideas and expertise together and facilitate local, metropolitan, and state discussions about the West’s future. Enhance local, regional, and state research and public policy discussions