Outstanding challenges in the transferability of ecological models

Predictive models are central to many scientific disciplines and vital for informing management in a rapidly changing world. However, limited understanding of the accuracy and precision of models transferred to novel conditions (their 'transferability') undermines confidence in their predictions. Here, 50 experts identified priority knowledge gaps which, if filled, will most improve model transfers. These are summarized into six technical and six fundamental challenges, which underlie the combined need to intensify research on the determinants of ecological predictability, including species traits and data quality, and develop best practices for transferring models. Of high importance is the identification of a widely applicable set of transferability metrics, with appropriate tools to quantify the sources and impacts of prediction uncertainty under novel conditions.Katherine L. Yates ... Alice R. Jones ... et al

Energy, risk, and reptilian reproductive effort: a reply to Niewiarowski and Dunham

[Extract] Based on simple mathematical models, Shine and Schwarzkopf (1992; SS) suggested that survival costs of reproduction were likely to be more important evolutionary determinants of reproductive effort (RE) than were growth costs in many reptiles, and hence that energy-based measures were unlikely to be of general use in testing predictions derived from RE theory. These conclusions were strongly challenged by Niewiarowski and Dunham (1994; ND), who argued that our models lacked generality. In this paper, we reexamine ND's analyses and show that their models actually support, rather than refute, our original conclusions

Intraspecific variation in the pelagic larval duration of tropical reef fishes

Estimates of pelagic larval duration (PLD) for 10 species of Pomacentridae and two species of Gobiidae were made. In eight of the 12 species examined, within-population mean PLDs differed between sampling times, locations within regions and among regions. In contrast, the range of these same PLD estimates overlapped at all spatial and temporal scales examined in 11 of the 12 species, but not between regions in one species (Amphiprion melanopus). Therefore, despite tight error estimates typically associated with estimates of PLD taken from a particular population at a particular time in some taxa, the overlapping ranges in PLD reported here indicate that the length of the pelagic larval phase is a much more plastic trait than previously appreciated. Within-species variation in PLD has considerable potential to provide further insights into the ecology and evolution of tropical reef fishes

Intraspecific variation in the pelagic larval duration of tropical reef fishes

Estimates of pelagic larval duration (PLD) for 10 species of Pomacentridae and two species of Gobiidae were made. In eight of the 12 species examined, within-population mean PLDs differed between sampling times, locations within regions and among regions. In contrast, the range of these same PLD estimates overlapped at all spatial and temporal scales examined in 11 of the 12 species, but not between regions in one species (Amphiprion melanopus). Therefore, despite tight error estimates typically associated with estimates of PLD taken from a particular population at a particular time in some taxa, the overlapping ranges in PLD reported here indicate that the length of the pelagic larval phase is a much more plastic trait than previously appreciated. Within-species variation in PLD has considerable potential to provide further insights into the ecology and evolution of tropical reef fishes

Marine protected areas increase resilience among coral reef communities

With marine biodiversity declining globally at accelerating rates, maximising the effectiveness of conservation has become a key goal for local, national and international regulators. Marine protected areas (MPAs) have been widely advocated for conserving and managing marine biodiversity yet, despite extensive research, their benefits for conserving non-target species and wider ecosystem functions remain unclear. Here, we demonstrate that MPAs can increase the resilience of coral reef communities to natural disturbances, including coral bleaching, coral diseases, Acanthaster planci outbreaks and storms. Using a 20-year time series from Australia's Great Barrier Reef, we show that within MPAs, (1) reef community composition was 21-38% more stable; (2) the magnitude of disturbance impacts was 30% lower and (3) subsequent recovery was 20% faster that in adjacent unprotected habitats. Our results demonstrate that MPAs can increase the resilience of marine communities to natural disturbance possibly through herbivory, trophic cascades and portfolio effects.Camille Mellin, M. Aaron MacNeil, Alistair J. Cheal, Michael J. Emslie, M. Julian Cale

Recruitment and the local dynamics of open marine populations

The majority of marine populations are demographically open; their replenishment is largely or exclusively dependent on a supply of juveniles from the plankton. In spite of much recent research, no consensus has yet been reached regarding the importance of recruitment relative to other demographic processes in determining local population densities. We argue 1. that demographic theory suggests that, except under restrictive and unlikely conditions, recruitment must influence local population density to some extent. Therefore, 2. the question as to whether the size of a particular population is limited by recruitment is misguided. Finally, 3. the effect of recruitment on population size can be difficult to detect but is nonetheless real. A major weakness of most existing studies is a lack of attention to the survival of recruits over appropriate scales of time and space. Acknowledgment of the multifactorial determination of population density should guide the design of future experimental studies of the demography of open populations

Local and regional patterns in the community structure of corals

Community ecologists now recognize that to understand patterns of biodiversity, there is an urgent need to synthesize large-scale phenomena with local processes. This demands a multi-scale or hierarchical approach. We have begun a multi-scale study of the composition and relative abundances of corals along the pacific diversity gradient, from Indonesia to French Polynesia. Our goals are to examine how local diversity responds to variation in the size of the regional species pool, and to quantify the relative variation in community composition at different scales (ie. among adjacent zones, sites, islands and regions). So far, we have sampled 52 sites on 14 islands within four regions (PNG, the Solomon Islands, Samoa, and French Polynesia), a total of 1,560 x 10m transects. Most variation in diversity and community structure occurs at the smallest and largest scales - among depth zones (the reef flat, crest and slope) and among geographic regions - compared to adjacent sites and islands that are much more homogeneous. Surveys of juvenile corals reveal major differences in the underlying dynamics of different regions. For example, over half of the coral recruits in PNG and the Solomon Islands belong to genera that are absent entirely in Samoa and French Polynesia. Widespread species typically vary in abundance among regions by an order of magnitude or more, highlighting the need to quantify biogeographical patterns using ecological as well as taxonomic data

Location and disturbance affect population genetic structure in four coral species of the genus Acropora on the Great Barrier Reef

The impact of a mass bleaching event on temporal and spatial population genetic structure in 4 scleractinian coral species in the Acropora aspera group was studied around the Palm Islands in the central Great Barrier Reef. Species status of sympatric populations of 2 of the 4 species, A. millepora and A. spathulata, was confirmed by the population genetic data; these species have recently been separated based on morphological and breeding characters. Spatial analyses of population samples from 2004 detected differences in the level of gene flow among locations. No significant genetic differentiation was inferred between conspecific populations at Orpheus and Pelorus Islands, which are both located in the northern part of the island group and separated by ~1000 m. In contrast, all populations at Fantome Island were genetically differentiated, despite this island being located only 11 km south. Sampling of A. millepora and A. pulchra in the year prior to the 1998 mass bleaching event enabled a temporal comparison across this event. The genetic composition of these populations changed between 1997 and 2004, but patterns of genetic differentiation among locations were similar in 1997 and 2004. Extensive mortality of these species following the 1998 bleaching event did not cause an apparent reduction in genetic diversity and identical multi-locus genotypes were encountered in both temporal samples, suggesting that re-growth of surviving genotypes contributed to the recovery of these populations. Comparisons among the 4 study species revealed lower genetic diversity in A. papillare, consistent with its low abundance throughout its distributional range