Massey Documents by Type

Now showing 1 - 3 of 3

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.
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.
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.

Massey Documents by Type

Browse

Filters

Settings

Sort By

Results per page

Search Results