Caroline E. Ridley

Crops gone wild: evolution of weeds and invasives from domesticated ancestors

The evolution of problematic plants, both weeds and invasives, is a topic of increasing interest. Plants that have evolved from domesticated ancestors have certain advantages for study. Because of their economic importance, domesticated plants are generally well‐characterized and readily available for ecogenetic comparison with their wild descendants. Thus, the evolutionary history of crop descendants has the potential to be reconstructed in some detail. Furthermore, growing crop progenitors with their problematic descendants in a common environment allows for the identification of significant evolutionary differences that correlate with weediness or invasiveness. We sought well‐established examples of invasives and weeds for which genetic and/or ethnobotanical evidence has confirmed their evolution from domesticates. We found surprisingly few cases, only 13. We examine our list for generalizations and then some selected cases to reveal how plant pests have evolved from domesticates. Despite their potential utility, crop descendants remain underexploited for evolutionary study. Promising evolutionary research opportunities for these systems are abundant and worthy of pursuit.

Biparental inbreeding and interremnant mating in a perennial prairie plant: Fitness consequences for progeny in their first eight years

Despite fundamental importance to population dynamics, mating system evolution, and conservation management, the fitness consequences of breeding patterns in natural settings are rarely directly and rigorously evaluated. We experimentally crossed Echinacea angustifolia, a widespread, perennial prairie plant undergoing radical changes in distribution and abundance due to habitat fragmentation. We quantified the effects of both biparental inbreeding and crossing between remnant populations on progeny survival and reproduction in the field over the first eight years. Lifetime fitness is notoriously difficult to assess particularly for iteroparous species because of the long sequence and episodic nature of selection events. Even with fitness data in hand, analysis is typically plagued by nonnormal distributions of overall fitness that violate the assumptions of the usual parametric statistical approaches. We applied aster modeling, which integrates the measurements of separate, sequential, nonnormally distributed annual fitness components, and estimated current biparental inbreeding depression at 68% in progeny of sibling‐mating. The effect of between‐remnant crossing on fitness was negligible. Given that relatedness among individuals in remnant populations is already high and dispersal very limited, inbreeding depression may profoundly affect future dynamics and persistence of these populations, as well as their genetic composition.

Biofuels: network analysis of the literature reveals key environmental and economic unknowns.

Despite rapid growth in biofuel production worldwide, it is uncertain whether decision-makers possess sufficient information to fully evaluate the impacts of the industry and avoid unintended consequences. Doing so requires rigorous peer-reviewed data and analyses across the entire range of direct and indirect effects. To assess the coverage of scientific research, we analyzed over 1600 peer-reviewed articles published between 2000 and 2009 that addressed 23 biofuels-related topics within four thematic areas: environment and human well-being, economics, technology, and geography. Greenhouse gases, fuel production, and feedstock production were well-represented in the literature, while trade, biodiversity, and human health were not. Gaps were especially striking across topics in the Southern Hemisphere, where the greatest potential socio-economic benefits, as well as environmental damages, may co-occur. There was strong asymmetry in the connectedness of research topics; greenhouse gases articles were twice as often connected to other topics as biodiversity articles. This could undermine the ability of scientific and economic analyses to adequately evaluate impacts and avoid significant unintended consequences. At the least, our review suggests caution in this developing industry and the need to pursue more interdisciplinary research to assess complex trade-offs and feedbacks inherent to an industry with wide-reaching potential impacts.

The Effect of Plant Inbreeding and Stoichiometry on Interactions with Herbivores in Nature: Echinacea angustifolia and Its Specialist Aphid

Fragmentation of once widespread communities may alter interspecific interactions by changing genetic composition of interacting populations as well as their abundances and spatial distributions. In a long-term study of a fragmented population of Echinacea angustifolia, a perennial plant native to the North American prairie, we investigated influences on its interaction with a specialist aphid and tending ants. We grew plant progeny of sib-matings (I), and of random pairings within (W) and between (B) seven remnants in a common field within 8 km of the source remnants. During the fifth growing season, we determined each plants burden of aphids and ants, as well as its size and foliar elemental composition (C, N, P). We also assayed composition (C, N) of aphids and ants. Early in the season, progeny from genotypic classes B and I were twice as likely to harbor aphids, and in greater abundance, than genotypic class W; aphid loads were inversely related to foliar concentration of P and positively related to leaf N and plant size. At the end of the season, aphid loads were indistinguishable among genotypic classes. Ant abundance tracked aphid abundance throughout the season but showed no direct relationship with plant traits. Through its potential to alter the genotypic composition of remnant populations of Echinacea, fragmentation can increase Echinaceas susceptibility to herbivory by its specialist aphid and, in turn, perturb the abundance and distribution of aphids.

Local adaptation and genetic effects on fitness: Calculations for exponential family models with random effects

Random effects are implemented for aster models using two approximations taken from Breslow and Clayton [J. Amer. Statist. Assoc. 88 (1993) 9–25]. Random effects are analytically integrated out of the Laplace approximation to the complete data log likelihood, giving a closed-form expression for an approximate missing data log likelihood. Third and higher derivatives of the complete data log likelihood with respect to the random effects are ignored, giving a closedform expression for second derivatives of the approximate missing data log likelihood, hence approximate observed Fisher information. This method is applicable to any exponential family random effects model. It is implemented in the CRAN package aster (R Core Team [R: A Language and Environment for Statistical Computing (2012) R Foundation for Statistical Computing], Geyer [R package aster (2012) http://cran.r-project.org/package=aster]). Applications are analyses of local adaptation in the invasive California wild radish (Raphanus sativus) and the slender wild oat (Avena barbata) and of additive genetic variance for fitness in the partridge pea (Chamaecrista fasciculata).

Biota connect aquatic habitats throughout freshwater ecosystem mosaics

Freshwater ecosystems are linked at various spatial and temporal scales by movements of biota adapted to life in water. We review the literature on movements of aquatic organisms that connect different types of freshwater habitats, focusing on linkages from streams and wetlands to downstream waters. Here, streams, wetlands, rivers, lakes, ponds, and other freshwater habitats are viewed as dynamic freshwater ecosystem mosaics (FEMs) that collectively provide the resources needed to sustain aquatic life. Based on existing evidence, it is clear that biotic linkages throughout FEMs have important consequences for biological integrity and biodiversity. All aquatic organisms move within and among FEM components, but differ in the mode, frequency, distance, and timing of their movements. These movements allow biota to recolonize habitats, avoid inbreeding, escape stressors, locate mates, and acquire resources. Cumulatively, these individual movements connect populations within and among FEMs and contribute to local and regional diversity, resilience to disturbance, and persistence of aquatic species in the face of environmental change. Thus, the biological connections established by movement of biota among streams, wetlands, and downstream waters are critical to the ecological integrity of these systems. Future research will help advance our understanding of the movements that link FEMs and their cumulative effects on downstream waters.

Applying gene flow science to environmental policy needs: a boundary work perspective

One application of gene flow science is the policy arena. In this article, we describe two examples in which the topic of gene flow has entered into the U.S. national environmental policymaking process: regulation of genetically engineered crops and clarification of the jurisdictional scope of the Clean Water Act. We summarize both current scientific understanding and the legal context within which gene flow science has relevance. We also discuss the process by which scientific knowledge has been synthesized and communicated to decision‐makers in these two contexts utilizing the concept of ‘boundary work’. Boundary organizations, the work they engage in to bridge the worlds of science, policy, and practice, and the boundary objects they produce to translate scientific knowledge existed in both examples. However, the specific activities and attributes of the objects produced varied based on the needs of the decision‐makers. We close with suggestions for how scientists can contribute to or engage in boundary work with policymakers.

Featured collection introduction: Connectivity of streams and wetlands to downstream waters

Connectivity is a fundamental but highly dynamic property of watersheds. Variability in the types and degrees of aquatic ecosystem connectivity presents challenges for researchers and managers seeking to accurately quantify its effects on critical hydrologic, biogeochemical, and biological processes. However, protecting natural gradients of connectivity is key to protecting the range of ecosystem services that aquatic ecosystems provide. In this featured collection, we review the available evidence on connections and functions by which streams and wetlands affect the integrity of downstream waters such as large rivers, lakes, reservoirs, and estuaries. The reviews in this collection focus on the types of waters whose protections under the U.S. Clean Water Act have been called into question by U.S. Supreme Court cases. We synthesize 40+ years of research on longitudinal, lateral, and vertical fluxes of energy, material, and biota between aquatic ecosystems included within the Act’s frame of reference. Many questions about the roles of streams and wetlands in sustaining downstream water integrity can be answered from currently available literature, and emerging research is rapidly closing data gaps with exciting new insights into aquatic connectivity and function at local, watershed, and regional scales. Synthesis of foundational and emerging research is needed to support science-based efforts to provide safe, reliable sources of fresh water for present and future generations. (KEY TERMS: ecological integrity; river networks; streams; wetlands; floodplains; riparian areas; watersheds; U.S. Clean Water Act.) Alexander, Laurie C., Ken M. Fritz, Kate A. Schofield, Bradley C. Autrey, Julie E. DeMeester, Heather E. Golden, David C. Goodrich, William G. Kepner, Hadas R. Kiperwas, Charles R. Lane, Stephen D. LeDuc, Scott G. Leibowitz, Michael G. McManus, Amina I. Pollard, Caroline E. Ridley, Melanie K. Vanderhoof, and Parker J. Wigington, Jr., 2018. Featured Collection Introduction: Connectivity of Streams and Wetlands to Downstream Waters. Journal of the American Water Resources Association (JAWRA) 54(2): 287–297. https://doi.org/10.1111/ 1752-1688.12630 Paper No. JAWRA-17-0107-P of the Journal of the American Water Resources Association (JAWRA). Received July 24, 2017; accepted January 22, 2018.

Timely delivery of scientific knowledge for environmental management: a Freshwater Science initiative

National Center for Environmental Assessment, Office of Research and Development, US Environmental Protection Agency, Washington, DC 20460 USA Department of Infrastructure Engineering, University of Melbourne, Parkville, Victoria 3010, Australia Centre for Evidence Informed Policy and Practice, Australia (https://ceipp.org.au/) Institute for Applied Ecology, University of Canberra, Bruce, Australian Capital Territory, 2617 Australia Centre for Environmental Policy, Imperial College, London, SW7 1NA UK