Journal Articles

Permanent URI for this collectionhttps://mro.massey.ac.nz/handle/10179/7915

Browse

Author: search.filters.author.Liggins LSubject: search.filters.subject.07 Agricultural and Veterinary Sciences

Search Results

Now showing 1 - 3 of 3
  • Thumbnail Image
    Item
    The population genetic structure of the urchin Centrostephanus rodgersii in New Zealand with links to Australia
    (1/09/2021) Thomas LJ; Liggins L; Banks SC; Beheregaray LB; Liddy M; McCulloch GA; Waters JM; Carter L; Byrne M; Cumming RA; Lamare MD
    The diadematid sea urchin Centrostephanus rodgersii occurs in Australia and New Zealand and has undergone recent southward range extension in Australia as a result of regional warming. Clarifying the population genetic structure of this species across its New Zealand range would allow a better understanding of recent and future mechanisms driving range changes in the species. Here, we use microsatellite DNA data to assess connectivity and genetic structure in 385 individuals from 14 locations across the Australian and New Zealand ranges of the species. We detected substantial genetic differentiation among C. rodgersii populations from Australia and New Zealand. However, the population from Port Stephens (located north of Newcastle), Australia, strongly clustered with New Zealand samples. This suggests that the New Zealand populations recently originated from this area, likely via larval transport in the Tasman Front flow that arises in this region. The weak population genetic structure and relatively low genetic diversity detected in New Zealand (global Fst = 0.0021) relative to Australia (global Fst = 0.0339) is consistent with the former population’s inferred history of recent climate-driven expansion. Population-level inbreeding is low in most populations, but were higher in New Zealand (global Fis = 0.0833) than in Australia (global Fis = 0.0202), suggesting that self-recruitment is playing an increasingly important role in the New Zealand region. Our results suggest that C. rodgersii is likely to spread southwards as ocean temperatures increase; therefore, it is crucial that researchers develop a clearer understanding of how New Zealand ecosystems will be reshaped by this species (and others) under climate change.
  • Thumbnail Image
    Item
    Genetic diversity targets and indicators in the CBD post-2020 Global Biodiversity Framework must be improved
    (Elsevier Ltd, 2020-08) Hoban S; Bruford M; D'Urban Jackson J; Lopes-Fernandes M; Heuertz M; Hohenlohe PA; Paz-Vinas I; Sjögren-Gulve P; Segelbacher G; Vernesi C; Aitken S; Bertola LD; Bloomer P; Breed M; Rodríguez-Correa H; Funk WC; Grueber CE; Hunter ME; Jaffe R; Liggins L; Mergeay J; Moharrek F; O'Brien D; Ogden R; Palma-Silva C; Pierson J; Ramakrishnan U; Simo-Droissart M; Tani N; Waits L; Laikre L
    The 196 parties to the Convention on Biological Diversity (CBD) will soon agree to a post-2020 global framework for conserving the three elements of biodiversity (genetic, species, and ecosystem diversity) while ensuring sustainable development and benefit sharing. As the most significant global conservation policy mechanism, the new CBD framework has far-reaching consequences- it will guide conservation actions and reporting for each member country until 2050. In previous CBD strategies, as well as other major conservation policy mechanisms, targets and indicators for genetic diversity (variation at the DNA level within species, which facilitates species adaptation and ecosystem function) were undeveloped and focused on species of agricultural relevance. We assert that, to meet global conservation goals, genetic diversity within all species, not just domesticated species and their wild relatives, must be conserved and monitored using appropriate metrics. Building on suggestions in a recent Letter in Science (Laikre et al., 2020) we expand argumentation for three new, pragmatic genetic indicators and modifications to two current indicators for maintaining genetic diversity and adaptive capacity of all species, and provide guidance on their practical use. The indicators are: 1) the number of populations with effective population size above versus below 500, 2) the proportion of populations maintained within species, 3) the number of species and populations in which genetic diversity is monitored using DNA-based methods. We also present and discuss Goals and Action Targets for post-2020 biodiversity conservation which are connected to these indicators and underlying data. These pragmatic indicators and goals have utility beyond the CBD; they should benefit conservation and monitoring of genetic diversity via national and global policy for decades to come.
  • Thumbnail Image
    Item
    Larval traits show temporally consistent constraints, but are decoupled from postsettlement juvenile growth, in an intertidal fish
    (John Wiley and Sons, Inc on behalf of the British Ecological Society, 8/08/2018) Thia JA; Riginos C; Liggins L; Figueira WF; McGuigan K
    1. Complex life cycles may evolve to dissociate distinct developmental phases in an organism's lifetime. However, genetic or environmental factors may restrict trait independence across life stages, constraining ontogenetic trajectories. Quantifying covariance across life stages and their temporal variability is fundamental in understanding life-history phenotypes and potential distributions and consequences for selection. 2. We studied developmental constraints in an intertidal fish (Bathygobius cocosensis: Gobiidae) with a discrete pelagic larval phase and benthic juvenile phase. We tested whether traits occurring earlier in life affected those expressed later, and whether larval traits were decoupled from postsettlement juvenile traits. Sampling distinct cohorts from three annual breeding seasons afforded tests of temporally variability in trait covariance. 3. From otoliths (fish ear stones), we measured hatch size, larval duration, pelagic growth (larval traits) and early postsettlement growth (juvenile trait) in 124 juvenile B. cocoensis. We used path analyses to model trait relationships with respect to their chronological expression, comparing models among seasons. We also modelled the effect of season and hatch date on each individual trait to quantify their inherent variability. 4. Our path analyses demonstrated a decoupling of larval traits on juvenile growth. Within the larval phase, longer larval durations resulted in greater pelagic growth, and larger size-at-settlement. There was also evidence that larger hatch size might reduce larval durations, but this effect was only marginally significant. Although pelagic and postsettlement growth were decoupled, pelagic growth had postsettlement consequences: individuals with high pelagic growth were among the largest fish at settlement, and remained among the largest early postsettlement. We observed no evidence that trait relationships varied among breeding seasons, but larval duration differed among breeding seasons, and was shorter for larvae hatching later within each season. 5. Overall, we demonstrate mixed support for the expectation that traits in different life stages are independent. While postsettlement growth was decoupled from larval traits, pelagic development had consequences for the size of newly settled juveniles. Temporal consistency in trait covariances implies that genetic and/or environmental factors influencing them were stable over our three-year study. Our work highlights the importance of individual developmental experiences and temporal variability in understanding population distributions of life-history traits.