ABSTRACT A field experiment was conducted to determine the relative contributions of immigration and sexual reproduction to the genetic structure of Mycosphaerella graminicola populations during the course of an epidemic. The genetic structure of M. graminicola populations sampled from wheat plots inoculated artificially with 10 isolates was compared with control plots infected naturally by air...

According to life-history theory, reproductive investments involve costs in terms of growth, future fecundity, and/or survival. However, studies to date have often failed to detect costs of reproduction, with survival costs among the less documented. We investigated the cost of reproduction in Helianthemum squamatum (Cistaceae), a short-lived perennial of semiarid Mediterranean environments. Af...

In this study we examine trends in body condition of three Cichla species native to the Cinaruco River, Venezuela. Specifically, we characterise the potential subsidy provided by migratory Semaprochilodus kneri to Cichla by comparing condition among species, hydrologic seasons and different size-classes (based on the ability to consume S. kneri assuming gape-limitation). All three species had l...

On the occasion of having collected three gravid Geochelone carbonaria in the Bolivian Chaco, data are given on oviducal eggs, as well as on five shells of eggs of the same species in the Museum collection. A review of the literature on the reproduction of G. carbonaria and of its sibling G. denticulata is presented, with an elementary statistical treatment of the data on number of clutches per...

There has been a great increase in breeding work on cool season turfgrass cultivars since the Plant Variety Protection (P.V.P.) Act was signed into law in December, 1970. This law, which is similar to the Plant Patent Law except that it covers sexual and asexual species, permits the developer of a new cultivar to exclude others from any unauthorized reproduction or marketing. This does not excl...

1. Explanations for the integration of migratory and non-migratory (resident) birds in the Neotropics have been complicated by the paradox that arthropod abundances are low when bird abundances reach their annual peak. The breeding currency hypothesis offers an explanation for this paradox by postulating that resident birds are limited in the breeding season by the availability of large arthrop...

What constitutes audience engagement? What elements of a show produce the most social activity? Much attention has been paid to Twitter’s ability to capture real-time audience reactions and sentiment towards a television show, but little is known about what subjects drive an individual to tweet (or conversely, not to tweet). Though common sense may suggest that especially provocative, humorous,...