Pacific Salmon, Oncorhynchus spp., and the Definition of "Species" Under the Endangered Species Act

For purposes ofthe Endangered Species Act (ESA), a "species" is defined to include "any distinct population segment of any species of vertebrate fish or wildlife which interbreeds when mature. "Federal agencies charged with carrying out the provisions of the ESA have struggled for over a decade to develop a consistent approach for interpreting the term "distinct population segment." This paper outlines such an approach and explains in some detail how it can be applied to ESA evaluations of anadromous Pacific salmonids. The following definition is proposed: A population (or group of populations) will be considered "distinct" (and hence a "species ")for purposes of the ESA if it represents an evolutionarily significant unit (ESU) of the biological species. A population must satisfy two criteria to be considered an ESU: 1) It must be substantially reproductively isolated from other conspecific population units, and 2) It must represent an important component in the evolutionary legacy of the species. Isolation does not have to be absolute, but it must be strong enough to permit evolutionarily important differences to accrue in different population units. The second criterion would be met if the population contributes substantially to the ecological/genetic diversity of the species as a whole. Insights into the extent of reproductive isolation can be provided by movements of tagged fish, natural recolonization rates observed in other populations, measurements of genetic differences between populations, and evaluations of the efficacy of natural barriers. Each of these methods has its limitations. Identification of physical barriers to genetic exchange can help define the geographic extent of distinct populations, but reliance on physical features alone can be misleading in the absence of supporting biological information. Physical tags provide information about the movements of individual fish but not the genetic consequences of migration. Furthermore, measurements ofc urrent straying or recolonization rates provide no direct information about the magnitude or consistency of such rates in the past. In this respect, data from protein electrophoresis or DNA analyses can be very useful because they reflect levels of gene flow that have occurred over evolutionary time scales. The best strategy is to use all available lines of evidence for or against reproductive isolation, recognizing the limitations of each and taking advantage of the often complementary nature of the different types of information. If available evidence indicates significant reproductive isolation, the next step is to determine whether the population in question is of substantial ecological/genetic importance to the species as a whole. In other words, if the population became extinct, would this event represent a significant loss to the ecological/genetic diversity of thes pecies? In making this determination, the following questions are relevant: 1) Is the population genetically distinct from other conspecific populations? 2) Does the population occupy unusual or distinctive habitat? 3) Does the population show evidence of unusual or distinctive adaptation to its environment? Several types of information are useful in addressing these questions. Again, the strengths and limitations of each should be kept in mind in making the evaluation. Phenotypic/life-history traits such as size, fecundity, and age and time of spawning may reflect local adaptations of evolutionary importance, but interpretation of these traits is complicated by their sensitivity to environmental conditions. Data from protein electrophoresis or DNA analyses provide valuable insight into theprocessofgenetic differentiation among populations but little direct information regarding the extent of adaptive genetic differences. Habitat differences suggest the possibility for local adaptations but do not prove that such adaptations exist. The framework suggested here provides a focal point for accomplishing the majorgoal of the Act-to conserve the genetic diversity of species and the ecosystems they inhabit. At the same time, it allows discretion in the listing of populations by requiring that they represent units of real evolutionary significance to the species. Further, this framework provides a means of addressing several issues of particular concern for Pacific salmon, including anadromous/nonanadromous population segments, differences in run-timing, groups of populations, introduced populations, and the role of hatchery fish

Nostalgia videogames as playable game criticism

The aim of this paper is to consider the emergence of nostalgia videogames in the context of playable game criticism. Mirroring the development of the nostalgia film in cinema, an increasing number of developers are creating videogames that are evocative of past gaming forms, designs, and styles. The primary focus of this paper is to explore the extent to which these nostalgia videogames could be considered games-on-games: games that offer a critical view on game design and development, framed by the nostalgia and cultural memory of both gamers and game developers. Theories of pastiche and parody as applied to literature, film, and art are used to form a basis for the examination of recent nostalgia videogames, all of which demonstrate a degree of reflection on the videogame medium

Why bridge the Uncanny Valley? Photorealism vs suspension of disbelief in animation

In recent years, the Uncanny Valley theory has been used to frame critical analysis of hyper­ real character animation in both film and computer games. The theory predicts that, as characters become more human­like in appearance, they run the risk of becoming unsettling to audiences. This dip in acceptability is the Uncanny Valley, and on the other side of this valley are the theoretical human simulants – characters co convincing that they are undistinguishable from real humans. However, the theory ­ which has its origins in robotics – can distract us from one of the primary aims of animation. While some character designers might be concerned with wowing their audiences with photorealistic character appearance and movement, other character animators are more concerned with exploring what it means to be human. Indeed, it can be argued that imagined characters that are unnatural in appearance and movement can in fact be more believably human than those that focus on visual mimicry. This article makes a case for an alternative approach to the Uncanny Valley for judging the aesthetics of human­like animation, with specific focus on the intentions of the animator in presenting characters that reflect human experience rather than replicate human appearance

Variational Bayes model averaging for graphon functions and motif frequencies inference in W-graph models

W-graph refers to a general class of random graph models that can be seen as a random graph limit. It is characterized by both its graphon function and its motif frequencies. In this paper, relying on an existing variational Bayes algorithm for the stochastic block models along with the corresponding weights for model averaging, we derive an estimate of the graphon function as an average of stochastic block models with increasing number of blocks. In the same framework, we derive the variational posterior frequency of any motif. A simulation study and an illustration on a social network complete our work

Introducing elliptic, an R Package for Elliptic and Modular Functions

This paper introduces the elliptic package of R routines, for numerical calculation of elliptic and related functions. Elliptic functions furnish interesting and instructive examples of many ideas of complex analysis, and the package illustrates these numerically and visually. A statistical application in fluid mechanics is presented.