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    Genetic Rescue and the Plight of Ponui Hybrids
    (Frontiers Media S.A., 2021-01-15) Undin M; Lockhart PJ; Hills SFK; Castro I; Vernesi C
    Long-term sustainable and resilient populations is a key goal of conservation. How to best achieve this is controversial. There are, for instance, polarized views concerning the fitness and conservation value of hybrid populations founded through multi-origin translocations. A classic example concerns Apteryx (kiwi) in New Zealand. The A. mantelli of Ponui Island constitute a hybrid population where the birds are highly successful in their island habitat. A key dilemma for managers is understanding the reason for this success. Are the hybrid birds of Ponui Island of “no future conservation value” as recently asserted, or do they represent an outstanding example of genetic rescue and an important resource for future translocations? There has been a paradigm shift in scientific thinking concerning hybrids, but the ecological significance of admixed genomes remains difficult to assess. This limits what we can currently predict in conservation science. New understanding from genome science challenges the sufficiency of population genetic models to inform decision making and suggests instead that the contrasting outcomes of hybridization, “outbreeding depression” and “heterosis,” require understanding additional factors that modulate gene and protein expression and how these factors are influenced by the environment. We discuss these findings and the investigations that might help us to better understand the birds of Ponui, inform conservation management of kiwi and provide insight relevant for the future survival of Apteryx.
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    The eggshell structure in apteryx; form, function, and adaptation
    (John Wiley and Sons, Ltd, 2021-04) Vieco-Galvez D; Castro I; Morel PCH; Chua WH; Loh M
    Apteryx is a genus of flightless birds endemic to New Zealand known to lay very large eggs in proportion to body weight. The eggshell of Apteryx is unusually thin and less porous than allometrically expected possibly as a compensation for a very long incubation period. Past studies have been carried out on Apteryx australis, a species which once comprised all kiwi with brown plumage, now separated into three distinct species. These species use different habitats and live at different latitudes and altitudes, therefore generating a need to revise our knowledge of the attributes of their eggshells. In this study, we measured the physical characteristics and water conductance on eggshell fragments of these three species and Great-spotted Kiwi and relate them to the environmental conditions of their respective environments; we also measured the water vapor conductance of Brown Kiwi eggs of late stages of incubation. We found that several trade-offs exist between incubation behavior, environmental conditions, and eggshell structure. We found differences between species in eggshell water vapor conductance seemingly related to altitude; Brown Kiwi and Rowi generally inhabiting lower altitudes had the highest conductance and Tokoeka, generally living in montane environments, the lowest. This is achieved by an increased eggshell thickness rather than a pore area reduction. Finally, the water vapor conductance late in incubation was 58% higher than infertile unincubated eggs, suggesting a drastic increase in conductance throughout the long incubation period. Using the values previously reported, we calculated the embryonic eggshell thinning to be 32.5% at the equatorial region of the eggshell. We describe several new features, such as triangular mineral particles in the cuticle, reported for the extinct Trigonoolithus amoei, and confirmed the existence of plugged pores. We suggest that these structures provide microbial protection needed by a burrow nesting species with a long incubation period.
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    Studies of how to improve translocation outcomes of Apteryx mantelli focusing on breeding, hybrids, diversity, and telomeres : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Ecology at Massey University - Te Kunenga Ki Purehuroa, Palmerston North, New Zealand
    (Massey University, 2021) Undin, Malin
    Genetic diversity contributes to the resilience of populations and, thus, to their potential to adapt to change and rebound after episodes of population decline. At the same time, many threatened species are confined to small populations with severely reduced access to gene flow. Since lost connectivity can result in inbreeding, translocations have become an increasingly important tool used by conservationists. However, the relative risks associated with inbreeding are difficult to weigh against potential negative fitness effects of outcrossing and hybridization. North Island brown kiwi, Apteryx mantelli, have a long, documented history of management and many severely isolated populations. The goal of this thesis was to determine current gaps in knowledge for successful genetic management of A. mantelli, explore closing those gaps using established hybrid populations and make recommendations for future translocations. First, information from past studies of Apteryx genetics was synthesised, which drew attention to the fact that available genetic data are insufficient for informing genetic management, predicting translocation outcomes, and linking genetic diversity to population fitness and local adaptation. Genome science combined with a strategic sampling regime was identified as crucial for acquiring the missing data. Second, an in-depth theoretical and empirical analysis of A. mantelli breeding behaviour was conducted. The results of this analysis showed that A. mantelli have the potential for polygamy, shows no signs of assortative mating, and breed in groups in certain conditions. These features of A. mantelli behaviour increase the likelihood of successful genetic rescue after reinforcement translocations. Next, the genetic diversity of the mixed-origin A. mantelli population on Ponui Island was investigated. Genotyping-by-sequencing analyses showed that this population constitutes a hybrid swarm in which founding parental genomes remain represented and levels of diversity are high compared to reference mainland populations. In addition to these studies, I conducted the first investigation of Apteryx telomeres. My theoretical analyses and empirical findings showed that telomere analyses of as long-lived species as A. mantelli are challenging and that telomere length is unlikely to be a suitable marker for determining Apteryx age and viability. Taken together, I suggest that the success of the hybrid population on Ponui Island indicates that mixed origin translocations should be considered as part of Apteryx management. However, I stress the need to (1) determine the role of local adaptation in Apteryx diversification, (2) study the impact of inbreeding, and (3) undertake investigations into informative markers of age and fitness on the individual and population-level. Investigation of epigenetic regulation of gene expression will be highly interesting for both these quests.
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    Investigating the physiological impacts of capture and handling on threatened avian species by using surrogate species as models : a thesis presented in partial fulfilment of the requirements for the degree Masters of Science in Conservation Biology at Massey University, Palmerston North, New Zealand
    (Massey University, 2013) Burns, Thomas Stephen
    The conservation management of many threatened species requires the capture and handling of wild individuals for monitoring, translocation or research purposes. However whenever wild animals are captured and handled there is the potential for these procedures to negatively impact the animal and result in altered behaviour or physiology, injury and even death. Therefore this thesis aimed to investigate what physiological impacts routine capture and handling may be having on threatened avian species in New Zealand by using surrogate species of birds as models for threatened birds. Layer hens (Gallus domesticus) were used as surrogates to model the physiological impacts of capture and handling on kiwi (Apteryx spp.). A treatment and control group of hens were serially blood sampled over 72 hours. Hens in the control group were placed in a box between blood samples and hens in the treatment group went through a simulation of a kiwi chase, capture and handling scenario. After 72 hours all birds were euthanized and their muscles examined histopathologically. Wild pukeko (Porphyrio porphyrio melanotus) captured using a net-gun at the Awapuni Sustainable Development Centre in Palmerston North were used as surrogates to model the physiological impacts of capture and handling on takahe (Porphyrio hochstetteri). Wild mallard ducks (Anas platyrhynchos) captured using a net-gun at Massey University’s Turitea campus were used as surrogates to model the physiological impacts of capture and handling on threatened waterfowl such as pateke/brown teal (Anas chlorotis), or whio/blue duck (Hymenolaimus malachorhynchos). All mallards and pukeko captured were serially blood sampled at capture (0 minutes), 30 and 120 minutes. Within each species there was a control group that was held in a box between samples and a treatment group which was handled according best practice protocol for takahe (for pukeko) or pateke (for mallards). A further group of pukeko was also shot using a rifle as comparison. To assess the physiological impact of capture, biochemical analytes measured included plasma concentrations of the enzymes creatine kinase (CK), aspartate aminotransferase (AST), glutamate dehydrogenase (GLDH) and the stress hormone corticosterone (CORT). In mallards and pukeko capture using the net-gun the plasma concentrations of uric acid (UA) were also measured. Capture was found to elicit a stress response in all three of the species studied as shown by elevated plasma CORT; however there were differences between species on the effect of capture on plasma CK, AST, GLDH and UA. The handling protocol was found to have minimal impact on the physiological response of any of the species and the impact of capture either overrode the effects of handling or handling protocol was simply not a significant factor on any of the biochemical analytes measured. Layer hens were found to have altered physiology at the commencement of the study, probably due to the high metabolic demands of egg production. There was also significant variation in their ‘normal’ physiology and physiological response between the two weeks they were studied. Layer hens are therefore considered to be inappropriate surrogates for kiwi or any wild bird. Baseline levels of the biochemical analytes of pukeko that were captured using a net-gun and those that were shot were similar. The time of day the pukeko were captured caused significant variation in the concentration of plasma GLDH and UA. Capture did cause significant elevations in plasma CK and AST showing subclinical muscle damage was occurring in the pukeko and this damage and the stress response was greater when the pukeko were captured in flight. Capture also had a significant if less clearly defined impact on renal and gastro-intestinal physiology. Seasonal variation and some time of day variation were observed in the concentration of CK in mallard ducks. While capture caused a significant stress response in captured mallards it did not have a significant effect on CK, GLDH or UA. Plasma AST concentrations decreased significantly following capture albeit by a very small amount. The difference found between species in their physiological response to similar procedures highlights that surrogate species may not be appropriate and validation between the surrogate and threatened species is required. Small differences in the capture technique may have a significant impact on the animal’s physiological response. In conclusion the handling protocol has a minimal physiological impact on these birds following capture and further research should focus on capture techniques and protocols. If surrogate species are used for further research then there should be some attempt to validate that the physiological response observed is similar in the threatened species.