Browsing by Author "Castro I"

Now showing 1 - 7 of 7
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    Aspects of the development of Ixodes anatis under different environmental conditions in the laboratory and in the field
    (BioMed Central Ltd, 2021-12) Bansal N; Pomroy WE; Heath ACG; Castro I
    BACKGROUND: Numerous laboratory and fewer field-based studies have found that ixodid ticks develop more quickly and survive better at temperatures between 18 °C and 26 °C and relative humidity (RH) between 75 and 94%. Ixodes anatis Chilton, 1904, is an endophilic, nidicolous species endemic to North Island brown kiwi (Apteryx mantelli) (NIBK) and the tokoeka (Apteryx australis), and little is known about the environmental conditions required for its development. The aims of this study were to determine and compare the conditions of temperature and RH that ensure the best survival of the kiwi tick and the shortest interstadial periods, in laboratory conditions and outdoors inside artificial kiwi burrows. METHODS: Free-walking engorged ticks were collected off wild kiwi hosts and placed in the laboratory under various fixed temperature and humidity regimes. In addition, sets of the collected ticks at different developmental stages were placed in artificial kiwi burrows. In both settings, we recorded the times taken for the ticks to moult to the next stage. RESULTS: Larvae and nymphs both showed optimum development at between 10 °C and 20 °C, which is lower than the optimum temperature for development in many other species of ixodid ticks. However, larvae moulted quicker and survived better when saturation deficits were < 1-2 mmHg (RH > 94%); in comparison, the optimum saturation deficits for nymph development were 1-10 mmHg. CONCLUSIONS: Our results suggest that the kiwi tick has adapted to the stable, but relatively cool and humid conditions in kiwi burrows, reflecting the evolutionary consequences of its association with the kiwi.
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    Captivity reduces diversity and shifts composition of the Brown Kiwi microbiome
    (BioMed Central Ltd, 2021-12) San Juan PA; Castro I; Dhami MK
    BACKGROUND: Captive rearing is often critical for animals that are vulnerable to extinction in the wild. However, few studies have investigated the extent to which captivity impacts hosts and their gut microbiota, despite mounting evidence indicating that host health is affected by gut microbes. We assessed the influence of captivity on the gut microbiome of the Brown Kiwi (Apteryx mantelli), a flightless bird endemic to New Zealand. We collected wild (n = 68) and captive (n = 38) kiwi feces at seven sites on the north island of New Zealand. RESULTS: Using bacterial 16 S rRNA and fungal ITS gene profiling, we found that captivity was a significant predictor of the kiwi gut bacterial and fungal communities. Captive samples had lower microbial diversity and different composition when compared to wild samples. History of coccidiosis, a gut parasite primarily affecting captive kiwi, showed a marginally significant effect. CONCLUSIONS: Our findings demonstrate captivity's potential to shape the Brown Kiwi gut microbiome, that warrant further investigation to elucidate the effects of these differences on health.
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    Dimorfismo sexual críptico en Sicalis flaveola (Aves: Thraupidae) en el trópico
    (Universidad de Caldas, 2021-01-01) Espinosa C; Castro I; Cruz-Bernate L
    The morphometric differences between the sexes in Sicalis flaveola from Valle del Cauca, southwest Colombia were evaluated. Sex was determined using molecular methods, reproductive behavior and morphological characters. A discriminant function analysis was carried out on 12 body measurements from individuals with mature plumage. Body measurements were very similar between the sexes in line with what was expected from monogamous passerines. Males were significantly larger than females in wings, rectrices, and distance between primary and secondary wing feathers while females had significantly wider beaks than males. An equation was found that that allows the identification of sex with an accuracy of 77.8 %. The morphometric method is proposed as an alternative of lower physiological and economic cost compared to molecular methods for determining the sex of individuals of the species. Se evaluaron las diferencias morfométricas entre sexos en individuos de Sicalis flaveola en el Valle del Cauca, suroccidente de Colombia. El sexo se determinó a partir de métodos moleculares, comportamiento reproductivo y caracteres morfológicos. Se realizó un análisis de función discriminante a partir de 12 medidas corporales de individuos adultos con plumaje maduro. Las medidas corporales fueron muy similares entre los sexos, acorde a lo esperado en paserinos monógamos. Los machos fueron significativamente más grandes que las hembras en alas, rectrices y distancia entre primarias y secundarias; mientras que las hembras tuvieron picos significativamente más anchos que los machos. Se encontró una ecuación que permite identificar el sexo con una exactitud del 77,8 %. Se propone el método morfométrico como una alternativa de menor costo fisiológico y económico en comparación con métodos moleculares para la determinación del sexo de individuos de la especie.
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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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    Mixed Mating in a Multi-Origin Population Suggests High Potential for Genetic Rescue in North Island Brown Kiwi, Apteryx mantelli
    (Frontiers Media S.A., 2021-08-10) Undin M; Lockhart PJ; Hills SFK; Armstrong DP; Castro I; Berger-Tal O
    Reinforcement translocations are increasingly utilised in conservation with the goal of achieving genetic rescue. However, concerns regarding undesirable results, such as genetic homogenisation or replacement, are widespread. One factor influencing translocation outcomes is the rate at which the resident and the introduced individuals interbreed. Consequently, post-release mate choice is a key behaviour to consider in conservation planning. Here we studied mating, and its consequences for genomic admixture, in the North Island brown kiwi Apteryx mantelli population on Ponui Island which was founded by two translocation events over 50 years ago. The two source populations used are now recognised as belonging to two separate management units between which birds differ in size and are genetically differentiated. We examined the correlation between male and female morphometrics for 17 known pairs and quantified the relatedness of 20 pairs from this admixed population. In addition, we compared the genetic similarity and makeup of 106 Ponui Island birds, including 23 known pairs, to birds representing the source populations for the original translocations. We found no evidence for size-assortative mating. On the contrary, genomic SNP data suggested that kiwi of one feather did not flock together, meaning that mate choice resulted in pairing between individuals that were less related than expected by random chance. Furthermore, the birds in the current Ponui Island population were found to fall along a gradient of genomic composition consistent with non-clustered representation of the two parental genomes. These findings indicate potential for successful genetic rescue in future Apteryx reinforcement translocations, a potential that is currently under utilised due to restrictive translocation policies. In light of our findings, we suggest that reconsideration of these policies could render great benefits for the future diversity of this iconic genus in New Zealand.
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    No evidence for sampling bias caused by capture method or time in Apteryx mantelli
    (New Zealand Ecological Society, 2023-06-14) Undin M; Castro I; Witehira R; Wood J
    Sampling bias can have dire consequences for research. One potential source of bias is combining different sampling methods in the same study. However, combining methods can be unavoidable, for instance, when sampling method selection depends upon factors such as population density or terrain. A case at hand is the use of night-time encounter catching by people or daytime catching using certified dogs for studies of Apteryx mantelli, North Island brown kiwi, in Aotearoa New Zealand. Here, we compare these sampling methods to determine whether (1) combining them risks inducing a demographic bias to the sample set, and (2) they differ in regards to blood parameters used for comparing populations (packed cell volume, glucose, plasma protein, haemoglobin). Sixty-five birds were caught during the day from their roosts using a certified dog, and 62 birds were caught at night while foraging. The results suggest that both methods capture a comparable subset of a population, with the potential exception that more very young juveniles were caught using the day method. Furthermore, no physiological effects were evident from comparing haematological parameters. We also found no difference in blood sampling success between night and day, but observed that blood extraction was more difficult at night. Hence, we demonstrate that either method, or a combination of both, can be considered for future studies. Notably, we found that night-time encounter catching had a superior success rate in very high-density populations. Since this method also negates dependency on the limited number of certified dogs, we suggest that benefits may exist through increasing the utilisation of night-time encounter catching in A. mantelli research. We suggest that future studies should consider measuring the stress levels caused by each of the methods, and quantify the effects of habitat type and terrain on sampling success.
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    Predicting breeding systems to guide conservation strategies: A kiwi example
    (Wiley-VCH GmbH, 2022-07-01) Undin M; Castro I; Goymann W
    The breeding system and mating strategy of a species are at the heart of its behavioral ecology and part of determining its population dynamics. Thus, understanding breeding and mating behavior, and its flexibility, is important for accurate population modeling and successful conservation management. Here, we combine previous work with species-specific data and phylogenetic context to shine the spotlight on the breeding system of North Island (NI) brown kiwi, Apteryx mantelli, in a conservation context. The NI brown kiwi is of wide interest as a ratite, which are known for their variable breeding biology both within and between species, and its dire need of conservation management. With the aid of data from a long-term study in a rare, high-density population, we conclude that, although NI brown kiwi have several features characteristic of monogamous bird species (substantial investment in offspring by both parents, long-life expectancy, and well-developed sense of olfaction), it has as many that are consistent with potential for polygamy (uneven quality and distribution of resources, long and asynchronous breeding season, super-precocial chicks, and non-monogamous relatives). Consequently, we suggest that (1) the breeding system of NI brown kiwi is more flexible than has been widely recognized, and (2) further study of NI brown kiwi mating behavior would greatly benefit its conservation planning. Specifically, the prevalence of polygamy will directly affect genetic admixture, maintaining of genetic diversity, and distribution of parentage—all crucial factors influencing translocation success and genetic rescue. We argue that the NI brown kiwi study system could contribute to the increased incorporation of behavioral aspects in conservation management, and we provide suggestions for informative studies that would facilitate this.