Research, Innovation and Commercialisation - Research Publications
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ItemBiosecurity interceptions of an invasive lizard: origin of stowaways and human-assisted spread within New Zealand(WILEY, 2013-02)Globalization, and the resultant movement of animals beyond their native range, creates challenges for biosecurity agencies. Limited records of unintentional introductions inhibit our understanding of the trade pathways, transport vectors and mechanisms through which hitchhiker organisms are spread as stowaways. Here, we adopt a phylogeographic approach to determine the source and human-mediated dispersal pathways of New Zealand's only invasive lizard, the delicate skink (Lampropholis delicata), intercepted by biosecurity agencies in New Zealand. Biosecurity agencies correctly predicted the source region of 77% of stowaways, which were usually solitary adults, arriving via air or sea pathways during the cooler months, evading initial border checks and alive when detected. New arrivals from Australia comprised 16% of detections originating from the region between Brisbane and Sydney. Our analyses indicate human-mediated dispersal has driven the post-border spread of L. delicata within New Zealand. Propagule pressure was substantially greater for L. delicata compared with the noninvasive, congeneric Lampropholis guichenoti. Our results highlight the transport pathways, spread mechanisms, and stowaway characteristics of Lampropholis lizards entering New Zealand, which could enhance current biosecurity protocols and prevent the establishment of additional lizard species.
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ItemPhylogeography of the Endangered Otago Skink, Oligosoma otagense: Population Structure, Hybridisation and Genetic Diversity in Captive Populations(PUBLIC LIBRARY SCIENCE, 2012-04-12)Climatic cooling and substantial tectonic activity since the late Miocene have had a pronounced influence on the evolutionary history of the fauna of New Zealand's South Island. However, many species have recently experienced dramatic range reductions due to habitat fragmentation and the introduction of mammalian predators and competitors. These anthropogenic impacts have been particularly severe in the tussock grasslands of the Otago region. The Otago skink (Oligosoma otagense), endemic to the region, is one of the most critically endangered vertebrates in New Zealand. We use mitochondrial DNA sequence data to investigate the evolutionary history of the Otago skink, examine its population genetic structure, and assess the level of genetic diversity in the individuals in the captive breeding program. Our data indicate that the Otago skink diverged from its closest relatives in the Miocene, consistent with the commencement of tectonic uplift of the Southern Alps. However, there is evidence for past introgression with the scree skink (O. waimatense) in the northern Otago-southern Canterbury region. The remnant populations in eastern Otago and western Otago are estimated to have diverged in the mid-Pliocene, with no haplotypes shared between these two regions. This divergence accounts for 95% of the genetic diversity in the species. Within both regions there is strong genetic structure among populations, although shared haplotypes are generally evident between adjacent localities. Although substantial genetic diversity is present in the captive population, all individuals originate from the eastern region and the majority had haplotypes that were not evident in the intensively managed populations at Macraes Flat. Our data indicate that eastern and western populations should continue to be regarded as separate management units. Knowledge of the genetic diversity of the breeding stock will act to inform the captive management of the Otago skink and contribute to a key recovery action for the species.
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ItemEnvironmental Flows Can Reduce the Encroachment of Terrestrial Vegetation into River Channels: A Systematic Literature Review(SPRINGER, 2013-11)Encroachment of riparian vegetation into regulated river channels exerts control over fluvial processes, channel morphology, and aquatic ecology. Reducing encroachment of terrestrial vegetation is an oft-cited objective of environmental flow recommendations, but there has been no systematic assessment of the evidence for and against the widely-accepted cause-and-effect mechanisms involved. We systematically reviewed the literature to test whether environmental flows can reduce the encroachment of terrestrial vegetation into river channels. We quantified the level of support for five explicit cause-effect hypotheses drawn from a conceptual model of the effects of flow on vegetation. We found that greater inundation, variously expressed as changes in the area, depth, duration, frequency, seasonality, and volume of surface water, generally reduces riparian vegetation abundance in channels, but most studies did not investigate the specific mechanisms causing these changes. Those that did show that increased inundation results in increased mortality, but also increased germination. The evidence was insufficient to determine whether increased inundation decreases reproduction. Our results contribute to hydro-ecological understanding by using the published literature to test for general cause-effect relationships between flow regime and terrestrial vegetation encroachment. Reviews of this nature provide robust support for flow management, and are more defensible than expert judgement-based approaches. Overall, we predict that restoration of more natural flow regimes will reduce encroachment of terrestrial vegetation into regulated river channels, partly through increased mortality. Conversely, infrequent deliveries of environmental flows may actually increase germination and subsequent encroachment.
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ItemAssessing the benefits and risks of translocations in changing environments: a genetic perspective(WILEY, 2011-11)Translocations are being increasingly proposed as a way of conserving biodiversity, particularly in the management of threatened and keystone species, with the aims of maintaining biodiversity and ecosystem function under the combined pressures of habitat fragmentation and climate change. Evolutionary genetic considerations should be an important part of translocation strategies, but there is often confusion about concepts and goals. Here, we provide a classification of translocations based on specific genetic goals for both threatened species and ecological restoration, separating targets based on 'genetic rescue' of current population fitness from those focused on maintaining adaptive potential. We then provide a framework for assessing the genetic benefits and risks associated with translocations and provide guidelines for managers focused on conserving biodiversity and evolutionary processes. Case studies are developed to illustrate the framework.