Sister taxa often differ phenotypically, yet we generally do not know whether trait divergence reflects adaptation to spatially-varying selection. In a reciprocal transplant experiment, we ask whether selection favors the native phenotype in two parapatric subspecies of Clarkia xantiana (Onagraceae), an annual plant endemic to California. We quantified phenotypic selection in each of the exclusive ranges and the contact zone in two years with contrasting climates. We predicted that in the arid, pollinator-scarce eastern region of the distribution, phenotypes of the native subspecies (parviflora) have an advantage: small leaves, slow leaf growth, accelerated flowering, and diminutive flowers. In the wetter, pollinator-rich, western range of subspecies xantiana, we expected selection for the opposite phenotypes. We predicted that temporal variation in selection would favor xantiana¬-like traits during the first wet El Niño year and parviflora-like traits in the second dry La Niña year. For subspecies xantiana, selection generally favored native phenotypes in the native garden. However, for parviflora, selection sometimes favored non-native trait values. We found little evidence for pollinator-mediated selection, subspecies differences in pollen limitation to reproduction, or temporal variation in selection. Phenotypic differentiation appears to reflect divergent selection in xantiana, but not parviflora.
A simple two-sector effort-regulation model, which assumes that the cost of job loss responds to labor's bargaining power and which acknowledges influences of institutional change, import penetration and shifting employment, can account for the declining real wages for non-supervisory workers in goods sector industries in the 1980s.
The operation of labor markets differs fundamentally from that of other markets because the commodity traded, hours of labor time, cannot be separated from human beings. Efficiency wage models, and effort-regulation (or shirking) models in particular address the issue of individual motivation by explicitly considering the influence of the wage on the worker's decision concerning the level of effort exerted. This paper offers a theoretical argument that a cost-based conception of union bargaining power is compatible with an effort-regulation/contested exchange framework.
This paper investigates causes of the dramatic increase in the wage-productivity gap—the divergence between the growth rates of aggregate productivity and real wages - in the post-1981 period. Using a two-step estimation procedure which incorporates three-digit industry wage regression coefficients into an aggregate wage growth identity equation, it finds that employment decline within unionized industries explains 18% of the post-1981 increase in the gap and that declining union ability to raise wages may explain as much as another 25%. Imports, on the other hand, do not appear to explain the gap independently of employment effects.
The terms of market exchange can, under certain conditions, even in competitive markets, reflect underlying power relationships. Bilateral market power exists in employment relationships whenever both workers and employers benefit from maintaining their association: whenever the value of the employment relationship exceeds the value of the next best alternative for both parties simultaneously. This paper develops a widely applicable model of bilateral market power in employment relationships along with some of its implications.
This paper addresses implicit bargaining power within employment relationships using a versatile model of labor market segmentation that combines labor discipline, performance pay, insider power, and fair wage principles. In the primary sector, fair wage comparisons, firm-specific human capital, and less perfect monitoring engender bilateral bargaining power, yielding high compensation, sometimes including a bonus. Secondary-sector employers exert unilateral bargaining power, via credible dismissal threats with no replacement costs, and offer no bonuses. Differential determinates of implicit bargaining power can potentially explain various phenomena, including nominal wage rigidity, union wage differentials, job-specific wage differentials, and gender or race-based wage differentials.
Undergraduate economics lags behind cutting-edge economic theory. The author briefly reviews six related advances that profoundly extend and deepen economic analysis: game-theoretic modeling, collective-action problems, information economics and contracting, social preference theory, conceptualizing rationality, and institutional theory. He offers suggestions for incorporating these into the undergraduate classes at various levels. He argues that game-theoretic representation of collective action problems offers a unifying framework, on par with supply and demand, for political economy. Blending in the other developments deepens our micro-level understanding of internal and external contract enforcement, with implications on nonclearing markets, power, and distribution. At the macro level, these concepts illuminate the role of institutions in economic development and long-term growth. Undergraduate curricula should incorporate these new approaches.
We provide a theoretical foundation for analyzing how social stigma and adopted behavioral traits affect the transmission of HIV across a population. We combine an evolutionary game-theoretic model—based on a relationship signaling stage game—with the SIR (susceptible-infected-recovered) model of disease transmission. Our evolutionary model specifies how two types of social stigma—that which accompanies an HIV+ condition and that which follows associating with an HIV+ partner—influence behavioral propensities to honestly report one’s condition (or not) and to unconditionally accept relationships (or not). With respect to reporting an HIV+ condition, we find that condition stigma impedes the fitness of honest reporting, whereas association stigma impedes the relative fitness of concealing an HIV+ condition; and both propensities can coexist in a polymorphic equilibrium. By linking our model to the SIR model, we find that condition stigma unambiguously enhances disease transmission by discouraging both honest reporting and a society’s acceptance of AIDS education, whereas association stigma has an ambiguous impact: on one hand it can impede HIV transmission by discouraging concealing behavior and unconditional relationship acceptance, but it also compromises a society’s acceptance of AIDS education. Our relatively simple evolutionary/SIR model offers a foundation for numerous theoretical extensions—such as applications to social network theory—as well as foundation for many testable empirical hypotheses.
The size of the automorphism group of a compact Riemann surface of genus g > 1 is bounded by 84(g-1). Curves with automorphism group of size this bound are called Hurwitz curves. In many cases the automorphism group of these curves is the projective special linear group PSL(2,q). We present a decomposition of the Jacobian varieties for all curves of this type and prove that no such Jacobian variety is simple.
Scholarly communication, in addition to referring to the disciplinary practices that structure the dissemination of scholarly knowledge, has become shorthand for two meanings: on the one hand, it refers to an analytic "author/reader" framework that seeks critical understanding of the entire life cycle of scholarly knowledge and the connected roles of researchers, teachers, students, funders, libraries, publishers, and other kinds of agencies in the creation, dissemination, critique, reuse, and preservation of knowledge. On the other hand, it embraces a public policy advocacy framework that critically examines the economic and legal relationships that constrain or facilitate the creation and flow of scholarly knowledge, urging recognition that knowledge is a kind of commons, with each discovery or innovation dependent on the accomplishments of earlier scholars. Despite the strong connections between the scholarly communications reform movement and research universities and research libraries, the economic, technological, and cultural changes under way in scholarly publishing affect many types of higher education institutions. Liberal arts colleges and their libraries also have a deep stake in the availability of scholarly literature and active engagement in efforts to illuminate and reform the scholarly publishing system, and have actively contributed to the movement. Many of the open access initiatives associated with the scholarly communication reform movement are directly relevant to the inquiry-based pedagogy characteristic of liberal arts college education.
The systems we use to record, communicate, and safeguard knowledge and experience – including our increasingly distributed and coordinated systems of curation – themselves increase complexity and risk, which will not be reduced, overall, by new or additional knowledge or technology. We must be careful not to overestimate what we think we know about the functioning of these complex systems, or to extrapolate too confidently from current trends.
This paper is a critical reconstruction of Luciano Floridi’s view of librarianship as “stewardship of a semantic environment,” a view that is at odds with the dominant tradition in which library and information science (LIS) is understood as social epistemology. Floridi’s work helps to explain the normative dimensions of librarianship in ways that epistemology does not, and his Philosophy of Information frames librarians’ traditional stewardship role in terms appropriate for our growing involvement in the management and preservation of information through its entire life cycle. Floridi’s work also helps illuminate what is coming to be called “knowledge as a commons.” Librarianship is concerned with maintaining and enhancing information environments over time, environments that include the behavior of the people who create and use them. The integrity of these environments makes possible the epistemic projects of faculty, students, and other researchers, but librarianship is not, itself, epistemological. Floridi’s ecological reframing of philosophy of information and information ethics, bridging the dichotomy between information and user, has a variety of implications for information literacy education and other academic library services in higher education. Citation: portal: Libraries and the Academy, Volume 15, Number 2, April 2015, pp. 267-286