The American Institute of Biological Sciences and the National Evolutionary Synthesis Center convened their fourth annual evolution symposium at the 2007 National Association of Biology Teachers conference in Atlanta, Georgia.

Advances in DNA (deoxyribonucleic acid) technology over the past 25 years have led to spectacularly precise forensic identification techniques, although some applications have also unleashed controversies regarding genetic privacy. Current molecular forensic work is pushing these technologies even further by analyzing extremely damaged DNA and by introducing RNA (ribonucleic acid) techniques to forensics.

Ionizing radiation is a ubiquitous stress to which all life is continuously exposed, and thus complex mechanisms have evolved to regulate cellular responses to radiation, including cell cycle arrest, DNA repair, and programmed cell death. Changes in gene expression shape part of the response to radiation, and have historically provided insight into the underlying mechanisms of that response. However, the advent of microarrays, which can measure expression of all the genes in a cell simultaneously, has transformed the study of gene expression, and is beginning to have an impact on both basic mechanistic and clinical studies. This article provides an overview of concepts in gene expression and microarray technology, and highlights their impacts on the study of radiation biology.

Biome-scale disturbances by eruptive herbivores provide valuable insights into species interactions, ecosystem function, and impacts of global change. We present a conceptual framework using one system as a model, emphasizing interactions across levels of biological hierarchy and spatiotemporal scales. Bark beetles are major natural disturbance agents in western North American forests. However, recent bark beetle population eruptions have exceeded the frequencies, impacts, and ranges documented during the previous 125 years. Extensive host abundance and susceptibility, concentrated beetle density, favorable weather, optimal symbiotic associations, and escape from natural enemies must occur jointly for beetles to surpass a series of thresholds and exert widespread disturbance. Opposing feedbacks determine qualitatively distinct outcomes at junctures at the biochemical through landscape levels. Eruptions occur when key thresholds are surpassed, prior constraints cease to exert influence, and positive feedbacks amplify across scales. These dynamics are bidirectional, as landscape features influence how lower-scale processes are amplified or buffered. Climate change and reduced habitat heterogeneity increase the likelihood that key thresholds will be exceeded, and may cause fundamental regime shifts. Systems in which endogenous feedbacks can dominate after external forces foster the initial breach of thresholds appear particularly sensitive to anthropogenic perturbations.

Bank erosion is integral to the functioning of river ecosystems. It is a geomorphic process that promotes riparian vegetation succession and creates dynamic habitats crucial for aquatic and riparian plants and animals. River managers and policymakers, however, generally regard bank erosion as a process to be halted or minimized in order to create landscape and economic stability. Here, we recognize bank erosion as a desirable attribute of rivers. Recent advances in our understanding of bank erosion processes and of associated ecological functions, as well as of the effects and failure of channel bank infrastructure for erosion control, suggest that alternatives to current management approaches are greatly needed. In this article, we develop a conceptual framework for alternatives that address bank erosion issues. The alternatives conserve riparian linkages at appropriate temporal and spatial scales, consider integral relationships between physical bank processes and ecological functions, and avoid secondary and cumulative effects that lead to the progressive channelization of rivers. By linking geomorphologic processes with ecological functions, we address the significance of channel bank erosion in sustainable river and watershed management.

Recent global environmental and social changes have created a set of “wicked problems” for which there are no optimal solutions. In this article, we illustrate the wicked nature of such problems by describing the effects of global warming on the wildfire regime and indigenous communities in Alaska, and we suggest an approach for minimizing negative impacts and maximizing positive outcomes. Warming has led to an increase in the areal extent of wildfire in Alaska, which increases fire risk to rural indigenous communities and reduces short-term subsistence opportunities. Continuing the current fire suppression policy would minimize these negative impacts, but it would also create secondary problems near communities associated with fuel buildup and contribute to a continuing decline in subsistence opportunities. Collaborations between communities and agencies to harvest flammable fuels for heating and electrical power generation near communities, and to use wildland fire for habitat enhancement in surrounding forests, could reduce community vulnerability to both the direct and the indirect effects of global climate change.

There has been a recent revival of interest in the role of ecology in speciation. The wing patterns of Heliconius butterflies are signals to predators as well as mates, and can cause strong reproductive isolation between populations. Reproductive isolation has been studied in some detail between the sympatric species Heliconius melpomene and Heliconius cydno, and in reviewing this work I show that habitat isolation and color pattern preference are by far the most important factors causing speciation. The surprising observation that genes for mate preference and color pattern are genetically associated implies divergence in sympatry or resulting from sexual selection. Color pattern is therefore an example of an ecological trait that contributes to speciation through pleiotropic effects on mate choice, although phylogenetic evidence shows that it is only one of many factors responsible for speciation in mimetic butterflies.

Anecdotal occurrence data (unverifiable observations of organisms or their sign) and inconclusive physical data are often used to assess the current and historical ranges of rare or elusive species. However, the use of such data for species conservation can lead to large errors of omission and commission, which can influence the allocation of limited funds and the efficacy of subsequent conservation efforts. We present three examples of biological misunderstandings, all of them with significant conservation implications, that resulted from the acceptance of anecdotal observations as empirical evidence. To avoid such errors, we recommend that a priori standards constrain the acceptance of occurrence data, with more stringent standards applied to the data for rare species. Because data standards are likely to be taxon specific, professional societies should develop specific evidentiary standards to use when assessing occurrence data for their taxa of interest.