(M)Unc13s in Active Zone Diversity: A Drosophila Perspective

The so-called active zones at pre-synaptic terminals are the ultimate filtering devices, which couple between action potential frequency and shape, and the information transferred to the post-synaptic neurons, finally tuning behaviors. Within active zones, the release of the synaptic vesicle operates from specialized “release sites.” The (M)Unc13 class of proteins is meant to define release sites topologically and biochemically, and diversity between Unc13-type release factor isoforms is suspected to steer diversity at active zones. The two major Unc13-type isoforms, namely, Unc13A and Unc13B, have recently been described from the molecular to the behavioral level, exploiting Drosophila being uniquely suited to causally link between these levels. The exact nanoscale distribution of voltage-gated Ca2+ channels relative to release sites (“coupling”) at pre-synaptic active zones fundamentally steers the release of the synaptic vesicle. Unc13A and B were found to be either tightly or loosely coupled across Drosophila synapses. In this review, we reported recent findings on diverse aspects of Drosophila Unc13A and B, importantly, their nano-topological distribution at active zones and their roles in release site generation, active zone assembly, and pre-synaptic homeostatic plasticity. We compared their stoichiometric composition at different synapse types, reviewing the correlation between nanoscale distribution of these two isoforms and release physiology and, finally, discuss how isoform-specific release components might drive the functional heterogeneity of synapses and encode discrete behavior.

Factors Influencing the Post-Release Movements of Translocated Fishers: Implications for Translocation Success

Long distance, post-release movements of translocated wildlife can be a key factor limiting translocation success. Yet, for many species, we have little or no understanding of factors that influence post-release movements. Translocations have been important for recovering fisher Pekania pennanti populations across the southern portion of their North American range. However, little is known about the post-release movements of translocated fishers and how these movements may be influenced by demographic or translocation-process factors. To restore fishers in Washington State, we moved 90 fishers from central British Columbia and released them at nine sites in the Olympic Fisher Recovery Area on the Olympic Peninsula of Washington from 2008 to 2010. We evaluated post-release movements of 48 fishers to determine both the distance and duration of movements prior to home range establishment. Fishers moved extensively following their release. Multi-model selection indicated a high level of support for the hypothesis that post-release movements differed by fisher sex and age; whereas, year of release had no apparent effect on movements, and release date had only a marginal influence on male movements. Mean distance (± 95% CI) from a release site to a home range was greater for adult males (62.0 ± 19.6 km) than for juvenile males (31.4 ± 16.0 km), adult females (30.9 ± 21.1 km), and juvenile females (29.0 ± 13.5 km). Mean number of days from release until home range establishment was similar for the sexes, however the variance in movement duration was greater for females. Twenty-six of 27 females established home ranges over an 11-month period (December-October), while 19 of 21 males did so within a 4-month period (April-July). Mean home range sizes differed between males (128.3 ± 21.1 km2) and females (63.5 ± 9.0 km2) and were among the largest reported for the species. A greater proportion of females (18 of 27; 67%) than males (8 of 21; 38%) established home ranges within or partially within the recovery area. Six females left a previously established home range during the breeding season, presumably to find breeding males. Given the large distances that fishers can move following release, translocation success could be furthered by releasing individuals at fewer sites in the interior of large reintroduction areas to facilitate greater exposure to a recovery area and greater opportunity to interact with conspecifics and potential mates.

Behavioural mechanisms affecting the success of translocations. An investigation using New Zealand’s rarest ratite, the rowi

<p>Translocations are increasingly being used for conservation management of threatened species (Sarrazin & Legendre, 2000). Outcomes are influenced by a range of factors including effects of early rearing experience, conspecific familiarity, density of resident conspecifics, and habitat quality at the release site, all of which may impact on the behaviour of released individuals and subsequent survival and fitness (Law & Linklater, 2007; Linklater & Swaisgood, 2008; Sarrazin & Legendre, 2000). Conservation success, defined as the realisation of goals set out at the start of a project, can be improved by detecting factors causing suboptimal outcomes and identifying potential solutions (Buner et al., 2011; Green et al., 2005; Mihoub et al., 2011). I aimed to expand current knowledge on factors influencing translocation outcomes by investigating the conservation management of the rowi (Apteryx rowi), the rarest species of kiwi. Current rowi conservation practices provide an opportunity to investigate this type of translocation management model. I provide new evidence and knowledge of behavioural mechanisms driving translocation success, include an expansion of current home range cognitive mapping theory relevant to conservation translocations, and present the first study of rowi home range behaviour (defined as the pattern of space use which leads to the emergence of a stable home range). Rowi conservation management involves removing eggs from the wild, hatching chicks in captivity, rearing on a predator free island until they are large enough to no longer be at risk of predation by stoats (Mustela erminae), then translocation back into the single remaining mainland population at Ōkārito forest. Over three years, experimental releases (n=66) were undertaken into both the existing population of rowi at South Ōkārito, and into an adjacent but unoccupied area of their former range at North Ōkārito. After intensive post-release monitoring, the effects of various elements of the translocation process on post-release survival, dispersal, conspecific association, habitat selection and home range behaviour were examined. An investigation into the effects of season of release, conspecific density, sex, and release group size on survival during the 90 day critical period following release, found release season and release group size are the most likely factors to influence post-release survival, with highest survival in spring, and for large release groups of four or more birds per release site. Habitat quality throughout the Ōkārito forest was estimated using invertebrate biomass as a proxy. A Geographic Information Systems (GIS) layer showing relative estimated invertebrate biomass was created and used to provide values of habitat quality at release locations and within home ranges. An investigation of the influence of habitat quality on post-release dispersal, conspecific association and home range behaviour found maximum dispersal distance was affected by the release site (North or South Ōkārito), and the interaction of release site and the estimated invertebrate biomass at the release location. Mean home ranges (± SE) of translocated rowi (3.35 ± 0.37 km²), were larger and of lower habitat quality than those of wild rowi (1.06 ± 0.09 km²). No effects of release group size on dispersal distance or conspecific association rates post-release were found. The effects of early rearing experience are proposed as a key factor influencing translocated rowi behaviour. By monitoring the survival, dispersal, conspecific association and home range behaviour resulting from the translocation of rowi reared in a non-natural social situation, I highlight the potential impact of prior social experience and social memory on cognitive mapping and home range establishment. This innovative approach has the potential to be a valuable expansion to current home range cognitive mapping theory, and warrants further study. Translocation is a vital tool in conservation, and has undoubtedly been instrumental in improving the situation of rowi since the first application to rowi conservation in the 1990s. This study has demonstrated that further improvements in the effectiveness and efficiency of translocations for conservation can be gained through sound scientific analysis of factors affecting the mechanisms leading to translocation success. Ongoing monitoring, analysis and reassessment of translocation management practices are recommended to ensure optimal conservation outcomes.</p>

Behavioural mechanisms affecting the success of translocations. An investigation using New Zealand’s rarest ratite, the rowi

<p>Translocations are increasingly being used for conservation management of threatened species (Sarrazin & Legendre, 2000). Outcomes are influenced by a range of factors including effects of early rearing experience, conspecific familiarity, density of resident conspecifics, and habitat quality at the release site, all of which may impact on the behaviour of released individuals and subsequent survival and fitness (Law & Linklater, 2007; Linklater & Swaisgood, 2008; Sarrazin & Legendre, 2000). Conservation success, defined as the realisation of goals set out at the start of a project, can be improved by detecting factors causing suboptimal outcomes and identifying potential solutions (Buner et al., 2011; Green et al., 2005; Mihoub et al., 2011). I aimed to expand current knowledge on factors influencing translocation outcomes by investigating the conservation management of the rowi (Apteryx rowi), the rarest species of kiwi. Current rowi conservation practices provide an opportunity to investigate this type of translocation management model. I provide new evidence and knowledge of behavioural mechanisms driving translocation success, include an expansion of current home range cognitive mapping theory relevant to conservation translocations, and present the first study of rowi home range behaviour (defined as the pattern of space use which leads to the emergence of a stable home range). Rowi conservation management involves removing eggs from the wild, hatching chicks in captivity, rearing on a predator free island until they are large enough to no longer be at risk of predation by stoats (Mustela erminae), then translocation back into the single remaining mainland population at Ōkārito forest. Over three years, experimental releases (n=66) were undertaken into both the existing population of rowi at South Ōkārito, and into an adjacent but unoccupied area of their former range at North Ōkārito. After intensive post-release monitoring, the effects of various elements of the translocation process on post-release survival, dispersal, conspecific association, habitat selection and home range behaviour were examined. An investigation into the effects of season of release, conspecific density, sex, and release group size on survival during the 90 day critical period following release, found release season and release group size are the most likely factors to influence post-release survival, with highest survival in spring, and for large release groups of four or more birds per release site. Habitat quality throughout the Ōkārito forest was estimated using invertebrate biomass as a proxy. A Geographic Information Systems (GIS) layer showing relative estimated invertebrate biomass was created and used to provide values of habitat quality at release locations and within home ranges. An investigation of the influence of habitat quality on post-release dispersal, conspecific association and home range behaviour found maximum dispersal distance was affected by the release site (North or South Ōkārito), and the interaction of release site and the estimated invertebrate biomass at the release location. Mean home ranges (± SE) of translocated rowi (3.35 ± 0.37 km²), were larger and of lower habitat quality than those of wild rowi (1.06 ± 0.09 km²). No effects of release group size on dispersal distance or conspecific association rates post-release were found. The effects of early rearing experience are proposed as a key factor influencing translocated rowi behaviour. By monitoring the survival, dispersal, conspecific association and home range behaviour resulting from the translocation of rowi reared in a non-natural social situation, I highlight the potential impact of prior social experience and social memory on cognitive mapping and home range establishment. This innovative approach has the potential to be a valuable expansion to current home range cognitive mapping theory, and warrants further study. Translocation is a vital tool in conservation, and has undoubtedly been instrumental in improving the situation of rowi since the first application to rowi conservation in the 1990s. This study has demonstrated that further improvements in the effectiveness and efficiency of translocations for conservation can be gained through sound scientific analysis of factors affecting the mechanisms leading to translocation success. Ongoing monitoring, analysis and reassessment of translocation management practices are recommended to ensure optimal conservation outcomes.</p>

Probabilistic Inverse Method for Source Localization Applied to ETEX and the 2017 Case of Ru-106 including Analyses of Sensitivity to Measurement Data

In recent years, cases of unexplained, elevated levels of radioactive particles have demonstrated an increasing need for efficient and robust source localization methods. In this study, a Bayesian method for source localization is developed and applied to two cases. First, the method is validated against the European tracer experiment (ETEX) and then applied to the still unaccounted for release of Ru-106 in the fall of 2017. The ETEX dataset, however, differs significantly from the Ru-106 dataset with regard to time resolution and the distance from the release site to the nearest measurements. Therefore, sensitivity analyses are conducted in order to test the method’s sensitivity to these parameters. The analyses show that the resulting source localization depends on both the observed temporal resolution and the existence of sampling stations close to the source. However, the method is robust, in the sense that reducing the amount of information in the dataset merely reduces the accuracy, and hence, none of the results are contradictory. When applied to the Ru-106 case, the results indicate that the Southern Ural region is the most plausible release area, and, as hypothesized by other studies, that the Mayak nuclear facility is the most likely release location.

Breeding biology and post-fledging dispersal of red-crowned parakeets (Cyanoramphus novaezelandiae) translocated to a fenced mainland sanctuary

<p>With human impacts like habitat destruction and climate change contributing to range contractions in species, translocations stand out as an important tool for conserving species suffering from these effects. However, an understanding of the life history of many threatened species prior to translocation is often lacking, but critical for translocation success. For example, dispersal away from the release site—particularly when a protected release site is surrounded by unmanaged habitat—can result in translocation failure, and therefore successful translocation practice must include an understanding of a species’ dispersal patterns. I conducted a study examining the breeding biology and post-fledging dispersal of a population of red-crowned parakeets Cyanoramphus novaezelandiae), or kakariki, recently translocated to a mainland sanctuary in Wellington, New Zealand. The sanctuary, ZEALANDIA, is fenced to exclude invasive mammalian predators; however, birds can and do leave. Approximately one-third of juveniles that dispersed outside the sanctuary were killed by predators. Kakariki post-fledging dispersal was male-biased, possibly driven by inbreeding avoidance, and distance dispersed decreased with increasing body condition. Parental age may have also influenced offspring dispersal. In addition, I found that kakariki reproductive success may be affected by age, and estimated lifetime reproductive success was >30 fledglings by age five. Conservation initiatives could work on controlling predators in currently unprotected reserves and around food sources that kakariki targeted, particularly in summer and autumn when many plants are fruiting and recently fledged juveniles are more active. Future translocations should consider selecting younger birds to translocate to take advantage of their high lifetime reproductive success and therefore improve viability of populations.</p>

Breeding biology and post-fledging dispersal of red-crowned parakeets (Cyanoramphus novaezelandiae) translocated to a fenced mainland sanctuary

<p>With human impacts like habitat destruction and climate change contributing to range contractions in species, translocations stand out as an important tool for conserving species suffering from these effects. However, an understanding of the life history of many threatened species prior to translocation is often lacking, but critical for translocation success. For example, dispersal away from the release site—particularly when a protected release site is surrounded by unmanaged habitat—can result in translocation failure, and therefore successful translocation practice must include an understanding of a species’ dispersal patterns. I conducted a study examining the breeding biology and post-fledging dispersal of a population of red-crowned parakeets Cyanoramphus novaezelandiae), or kakariki, recently translocated to a mainland sanctuary in Wellington, New Zealand. The sanctuary, ZEALANDIA, is fenced to exclude invasive mammalian predators; however, birds can and do leave. Approximately one-third of juveniles that dispersed outside the sanctuary were killed by predators. Kakariki post-fledging dispersal was male-biased, possibly driven by inbreeding avoidance, and distance dispersed decreased with increasing body condition. Parental age may have also influenced offspring dispersal. In addition, I found that kakariki reproductive success may be affected by age, and estimated lifetime reproductive success was >30 fledglings by age five. Conservation initiatives could work on controlling predators in currently unprotected reserves and around food sources that kakariki targeted, particularly in summer and autumn when many plants are fruiting and recently fledged juveniles are more active. Future translocations should consider selecting younger birds to translocate to take advantage of their high lifetime reproductive success and therefore improve viability of populations.</p>

Pigeons retain partial memories of homing paths years after learning them individually, collectively or culturally

Memory of past experience is central to many animal decisions, but how long specific memories can influence behaviour is poorly understood. Few studies have reported memories retrieved after several years in non-human animals, especially for spatial tasks, and whether the social context during learning could affect long-term memory retention. We investigated homing pigeons' spatial memory by GPS-recording their homing paths from a site 9 km from their loft. We compared solo flights of naive pigeons with those of pigeons that had last homed from this site 3–4 years earlier, having learnt a homing route either alone (individual learning), together with a naive partner (collective learning) or within cultural transmission chains (cultural learning). We used as a control a second release site unfamiliar to all pigeons. Pigeons from all learning treatments outperformed naive birds at the familiar (but not the unfamiliar) site, but the idiosyncratic routes they formerly used several years before were now partially forgotten. Our results show that non-human animals can use their memory to solve a spatial task years after they last performed it, irrespective of the social context during learning. They also suggest that without reinforcement, landmarks and culturally acquired ‘route traditions' are gradually forgotten.

Returning an Endemic Frog to the New Zealand Mainland: Transfer and Adaptive Management of Leiopelma pakeka at Karori Sanctuary, Wellington

<p>Karori Sanctuary (252 ha) is a fenced restoration site in Wellington, New Zealand from which all species of introduced mammals have been eradicated except house mice (Mus musculus). In 2006, the endemic New Zealand frog Leiopelma pakeka was transferred to Karori Sanctuary as part of a long term plan to restore the site's original biota. This was a significant event in that it was the first re-introduction of a New Zealand frog to a mainland site, the first New Zealand amphibian translocation for the purpose of restoration and the first time L. pakeka were released into habitat also occupied by an introduced mammal. An adaptive management regime facilitated research within the constraints of a community restoration project for which only a small population (n=60) was made available for release. Two groups (n = 30) were released into mouse-proof enclosures in February and October, 2006. Survival was high (97%) and frogs maintained a healthy body condition. Breeding was not detected during the first year and this was attributed to an inappropriate sex ratios that were restructured in April 2007 when half of the frogs (n= 29) were removed from the enclosures and released into forest habitat. The survival, condition and recruitment of frogs living inside and outside of the mouse-proof enclosures were compared. Both groups initially had a similar recapture rate, but after one year, just one frog (3%) was recaptured outside the enclosure compared with 27 adults (93%) and fourteen juveniles captured within the enclosure. In March 2009, 26 of the 29 individuals originally released into the enclosure were recaptured and a further ten juveniles were captured for the first time. No individuals have been sighted outside the enclosure since March 2008. Post-release movements did not explain the apparent decline of the population living outside of the enclosure. The mean distance dispersed during the first month after release (3.4 +/- 0.05 m) did not significantly increase after eight months (4.2 +/- 0.05 m) and the maximum-recorded dispersal distance was 7.0 m. The centre of activity of the nine frogs captured > 5 occasions were all within 3 m of the release site and kernel estimates of high habitat usage clustered around artificially constructed rock piles. Predation by house mice and/or native species such as little spotted kiwi (Apteryx owenii) were considered the most likely explanation for the failure to recapture frogs outside of the enclosure, especially those frogs that appeared to have settled at the release site. The extremely low number of individuals released outside of the enclosure exacerbated the impact of processes acting on the founding population. Recommendations are provided for the next adaptive management stage and include transferring an additional 100 frogs from Maud Island for release into forest habitat outside of the mouse-proof enclosure. Post-release movements should be restricted and all potential predators except house mice excluded. The population within the enclosures should be retained as is. Finally, the viability including L. pakeka in attempts to reconstruct mainland communities is examined.</p>

Returning an Endemic Frog to the New Zealand Mainland: Transfer and Adaptive Management of Leiopelma pakeka at Karori Sanctuary, Wellington

<p>Karori Sanctuary (252 ha) is a fenced restoration site in Wellington, New Zealand from which all species of introduced mammals have been eradicated except house mice (Mus musculus). In 2006, the endemic New Zealand frog Leiopelma pakeka was transferred to Karori Sanctuary as part of a long term plan to restore the site's original biota. This was a significant event in that it was the first re-introduction of a New Zealand frog to a mainland site, the first New Zealand amphibian translocation for the purpose of restoration and the first time L. pakeka were released into habitat also occupied by an introduced mammal. An adaptive management regime facilitated research within the constraints of a community restoration project for which only a small population (n=60) was made available for release. Two groups (n = 30) were released into mouse-proof enclosures in February and October, 2006. Survival was high (97%) and frogs maintained a healthy body condition. Breeding was not detected during the first year and this was attributed to an inappropriate sex ratios that were restructured in April 2007 when half of the frogs (n= 29) were removed from the enclosures and released into forest habitat. The survival, condition and recruitment of frogs living inside and outside of the mouse-proof enclosures were compared. Both groups initially had a similar recapture rate, but after one year, just one frog (3%) was recaptured outside the enclosure compared with 27 adults (93%) and fourteen juveniles captured within the enclosure. In March 2009, 26 of the 29 individuals originally released into the enclosure were recaptured and a further ten juveniles were captured for the first time. No individuals have been sighted outside the enclosure since March 2008. Post-release movements did not explain the apparent decline of the population living outside of the enclosure. The mean distance dispersed during the first month after release (3.4 +/- 0.05 m) did not significantly increase after eight months (4.2 +/- 0.05 m) and the maximum-recorded dispersal distance was 7.0 m. The centre of activity of the nine frogs captured > 5 occasions were all within 3 m of the release site and kernel estimates of high habitat usage clustered around artificially constructed rock piles. Predation by house mice and/or native species such as little spotted kiwi (Apteryx owenii) were considered the most likely explanation for the failure to recapture frogs outside of the enclosure, especially those frogs that appeared to have settled at the release site. The extremely low number of individuals released outside of the enclosure exacerbated the impact of processes acting on the founding population. Recommendations are provided for the next adaptive management stage and include transferring an additional 100 frogs from Maud Island for release into forest habitat outside of the mouse-proof enclosure. Post-release movements should be restricted and all potential predators except house mice excluded. The population within the enclosures should be retained as is. Finally, the viability including L. pakeka in attempts to reconstruct mainland communities is examined.</p>