Hastings Alan

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  • Article
    Employing plant functional groups to advance seed dispersal ecology and conservation
    (Oxford University Press, 2019-02-17) Aslan, Clare E. ; Beckman, Noelle G. ; Rogers, Haldre S. ; Bronstein, Judith L. ; Zurell, Damaris ; Hartig, Florian ; Shea, Katriona ; Pejchar, Liba ; Neubert, Michael G. ; Poulsen, John R. ; Hille Ris Lambers, Janneke ; Miriti, Maria ; Loiselle, Bette ; Effiom, Edu ; Zambrano, Jenny ; Schupp, Eugene W. ; Pufal, Gesine ; Johnson, Jeremy ; Bullock, James M. ; Brodie, Jedediah ; Bruna, Emilio ; Cantrell, Robert Stephen ; Decker, Robin ; Fricke, Evan ; Gurski, Katherine ; Hastings, Alan ; Kogan, Oleg ; Razafindratsima, Onja ; Sandor, Manette ; Schreiber, Sebastian ; Snell, Rebecca ; Strickland, Christopher ; Zhou, Ying
    Seed dispersal enables plants to reach hospitable germination sites and escape natural enemies. Understanding when and how much seed dispersal matters to plant fitness is critical for understanding plant population and community dynamics. At the same time, the complexity of factors that determine if a seed will be successfully dispersed and subsequently develop into a reproductive plant is daunting. Quantifying all factors that may influence seed dispersal effectiveness for any potential seed-vector relationship would require an unrealistically large amount of time, materials and financial resources. On the other hand, being able to make dispersal predictions is critical for predicting whether single species and entire ecosystems will be resilient to global change. Building on current frameworks, we here posit that seed dispersal ecology should adopt plant functional groups as analytical units to reduce this complexity to manageable levels. Functional groups can be used to distinguish, for their constituent species, whether it matters (i) if seeds are dispersed, (ii) into what context they are dispersed and (iii) what vectors disperse them. To avoid overgeneralization, we propose that the utility of these functional groups may be assessed by generating predictions based on the groups and then testing those predictions against species-specific data. We suggest that data collection and analysis can then be guided by robust functional group definitions. Generalizing across similar species in this way could help us to better understand the population and community dynamics of plants and tackle the complexity of seed dispersal as well as its disruption.
  • Article
    Complexity in ecology and conservation : mathematical, statistical, and computational challenges
    (American Institute of Biological Sciences, 2005-06) Green, Jessica L. ; Hastings, Alan ; Arzberger, Peter ; Ayala, Francisco J. ; Cottingham, Kathryn L. ; Cuddingham, Kim ; Davis, Frank ; Dunne, Jennifer A. ; Fortin, Marie-Josee ; Gerber, Leah ; Neubert, Michael G.
    Creative approaches at the interface of ecology, statistics, mathematics, informatics, and computational science are essential for improving our understanding of complex ecological systems. For example, new information technologies, including powerful computers, spatially embedded sensor networks, and Semantic Web tools, are emerging as potentially revolutionary tools for studying ecological phenomena. These technologies can play an important role in developing and testing detailed models that describe real-world systems at multiple scales. Key challenges include choosing the appropriate level of model complexity necessary for understanding biological patterns across space and time, and applying this understanding to solve problems in conservation biology and resource management. Meeting these challenges requires novel statistical and mathematical techniques for distinguishing among alternative ecological theories and hypotheses. Examples from a wide array of research areas in population biology and community ecology highlight the importance of fostering synergistic ties across disciplines for current and future research and application.
  • Article
    Advancing an interdisciplinary framework to study seed dispersal ecology
    (Oxford University Press, 2019-08-19) Beckman, Noelle G. ; Aslan, Clare E. ; Rogers, Haldre S. ; Kogan, Oleg ; Bronstein, Judith L. ; Bullock, James M. ; Hartig, Florian ; Hille Ris Lambers, Janneke ; Zhou, Ying ; Zurell, Damaris ; Brodie, Jedediah ; Bruna, Emilio ; Cantrell, Robert Stephen ; Decker, Robin ; Effiom, Edu ; Fricke, Evan ; Gurski, Katherine ; Hastings, Alan ; Johnson, Jeremy ; Loiselle, Bette ; Miriti, Maria ; Neubert, Michael G. ; Pejchar, Liba ; Poulsen, John R. ; Pufal, Gesine ; Razafindratsima, Onja ; Sandor, Manette ; Shea, Katriona ; Schreiber, Sebastian ; Schupp, Eugene W. ; Snell, Rebecca ; Strickland, Christopher ; Zambrano, Jenny
    Although dispersal is generally viewed as a crucial determinant for the fitness of any organism, our understanding of its role in the persistence and spread of plant populations remains incomplete. Generalizing and predicting dispersal processes are challenging due to context dependence of seed dispersal, environmental heterogeneity and interdependent processes occurring over multiple spatial and temporal scales. Current population models often use simple phenomenological descriptions of dispersal processes, limiting their ability to examine the role of population persistence and spread, especially under global change. To move seed dispersal ecology forward, we need to evaluate the impact of any single seed dispersal event within the full spatial and temporal context of a plant’s life history and environmental variability that ultimately influences a population’s ability to persist and spread. In this perspective, we provide guidance on integrating empirical and theoretical approaches that account for the context dependency of seed dispersal to improve our ability to generalize and predict the consequences of dispersal, and its anthropogenic alteration, across systems. We synthesize suitable theoretical frameworks for this work and discuss concepts, approaches and available data from diverse subdisciplines to help operationalize concepts, highlight recent breakthroughs across research areas and discuss ongoing challenges and open questions. We address knowledge gaps in the movement ecology of seeds and the integration of dispersal and demography that could benefit from such a synthesis. With an interdisciplinary perspective, we will be able to better understand how global change will impact seed dispersal processes, and potential cascading effects on plant population persistence, spread and biodiversity.
  • Article
    Disentangling trophic interactions inside a Caribbean marine reserve
    (Ecological Society of America, 2010-10) Kellner, Julie B. ; Litvin, Steven Y. ; Hastings, Alan ; Micheli, Fiorenza ; Mumby, Peter J.
    Recent empirical studies have demonstrated that human activities such as fishing can strongly affect the natural capital and services provided by tropical seascapes. However, policies to mitigate anthropogenic impacts can also alter food web structure and interactions, regardless of whether the regulations are aimed at single or multiple species, with possible unexpected consequences for the ecosystems and their associated services. Complex community response to management interventions have been highlighted in the Caribbean, where, contrary to predictions from linear food chain models, a reduction in fishing intensity through the establishment of a marine reserve has led to greater biomass of herbivorous fish inside the reserve, despite an increased abundance of large predatory piscivores. This positive multi-trophic response, where both predators and prey benefit from protection, highlights the need to take an integrated approach that considers how numerous factors control species coexistence in both fished and unfished systems. In order to understand these complex relationships, we developed a general model to examine the trade-offs between fishing pressure and trophic control on reef fish communities, including an exploration of top-down and bottom-up effects. We then validated the general model predictions by parameterizing the model for a reef system in the Bahamas in order to tease apart the wide range of species responses to reserves in the Caribbean. Combining the development of general theory and site-specific models parameterized with field data reveals the underlying driving forces in these communities and enables us to make better predictions about possible population and community responses to different management schemes.