University of Guelph

About: University of Guelph is a education organization based out in Guelph, Ontario, Canada. It is known for research contribution in the topics: Population & Gene. The organization has 26542 authors who have published 50553 publications receiving 1715255 citations. The organization is also known as: U of G & Guelph University.

Varroa destructor is the main culprit for the death and reduced populations of overwintered honey bee (Apis mellifera) colonies in Ontario, Canada

Abstract: The relative effect of parasite levels, bee population size, and food reserves on winter mortality and post winter populations of honey bee colonies was estimated. More than 400 colonies were monitored throughout three seasons in Ontario, Canada. Most of the colonies were infested with varroa mites during the fall (75.7%), but only 27.9% and 6.1% tested positive to nosema disease and tracheal mites, respectively. Winter colony mortality was 27.2%, and when examined as a fraction of all morbidity factors, fall varroa mite infestations were the leading cause of colony mortality (associated to > 85% of colony deaths), followed by fall bee populations and food reserves. Varroa-infested colonies, with weak populations and low food reserves in the fall, significantly decreased spring colony populations, whereas varroa infestations and Nosema infections in the spring, significantly decreased bee populations by early summer. Overall, results suggest that varroa mites could be the main culprit for the death and reduced populations of overwintered honey bee colonies in northern climates.

Annotated checklist of the birds of Brazil by the Brazilian Ornithological Records Committee / Lista comentada das aves do Brasil pelo Comitê Brasileiro de Registros Ornitológicos

Abstract: Since 2005, the Brazilian Ornithological Records Committee (CBRO) has published updated checklists of Brazilian birds almost every year. Herein, we present a completely new and annotated version of our checklist. For the first time, we list all bird subspecies known from Brazil that are currently accepted by at least one key ornithological reference work. The inclusion of the subspecies should be seen as a synthesis, and not as a taxonomic endorsement. As such, we include in the new checklist 1919 avian species, 910 of which are treated as polytypic in reference works (2042 subspecies), totaling 3051 taxa at the species and subspecies level. We anticipate that several of the subspecies included in our list may be subject to future taxonomic upgrades to species status, while others will probably be shown to be invalid in the light of future taxonomic studies. The results highlight Brazil as a megadiverse country and reinforce the need for proper enforcement of political tools, laws and international commitments assumed by the country to preserve its biodiversity.

Density triggers maternal hormones that increase adaptive offspring growth in a wild mammal.

Abstract: In fluctuating environments, mothers may enhance the fitness of their offspring by adjusting offspring phenotypes to match the environment they will experience at independence. In free-ranging red squirrels, natural selection on offspring postnatal growth rates varies according to population density, with selection favoring faster-growing offspring under high-density conditions. We show that exposing mothers to high-density cues, accomplished via playbacks of territorial vocalizations, led to increased offspring growth rates in the absence of additional food resources. Experimental elevation of actual and perceived density induced higher maternal glucocorticoid levels, and females with naturally or experimentally increased glucocorticoids produced offspring that grew faster than controls. Therefore, social cues reflecting population density were sufficient to elicit increased offspring growth through an adaptive hormone-mediated maternal effect.