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 & Poison control. The organization has 26542 authors who have published 50553 publications receiving 1715255 citations. The organization is also known as: U of G & Guelph University.

Phylogenetic trait conservatism and the evolution of functional trade-offs in arbuscular mycorrhizal fungi.

Abstract: The diversity of functional and life-history traits of organisms depends on adaptation as well as the legacy of shared ancestry. Although the evolution of traits in macro-organisms is well studied, relatively little is known about character evolution in micro-organisms. Here, we surveyed an ancient and ecologically important group of microbial plant symbionts, the arbuscular mycorrhizal (AM) fungi, and tested hypotheses about the evolution of functional and life-history traits. Variation in the extent of root and soil colonization by AM fungi is constrained to a few nodes basal to the most diverse groups within the phylum, with relatively little variation associated with recent divergences. We found no evidence for a trade-off in biomass allocated to root versus soil colonization in three published glasshouse experiments; rather these traits were positively correlated. Partial support was observed for correlated evolution between fungal colonization strategies and functional benefits of the symbiosis to host plants. The evolution of increased soil colonization was positively correlated with total plant biomass and shoot phosphorus content. Although the effect of AM fungi on infection by root pathogens was phylogenetically conserved, there was no evidence for correlated evolution between the extent of AM fungal root colonization and pathogen infection. Variability in colonization strategies evolved early in the diversification of AM fungi, and we propose that these strategies were influenced by functional interactions with host plants, resulting in an evolutionary stasis resembling trait conservatism.

Biological carryover effects: linking common concepts and mechanisms in ecology and evolution

Abstract: The term 'carryover effect' originally arose from repeated measures clinical experiments. However, the term has more recently been applied to ecological and evolutionary studies, often in migratory systems, which has led to an emphasis on non-lethal effects across seasons. In this article, we suggest that ecological carryover effects can also occur between life-history stages, developmental stages, physiological states, or social situations, and each will be associated with a discrete time-scale. Therefore, we propose the working definition: In an ecological context, carryover effects occur in any situation in which an individual's previous history and experience explains their current performance in a given situation. This concept of carryover effects provides an explicit but highly flexible context for examining the mechanisms that drive non-lethal interactions between distinct periods of an organism's lifetime, and unites the currently disparate fields investigating these effects in ecological systems. Greater communication among research fields and identifying mechanisms of carryover effects at different time scales will ultimately lead to a better understanding of the factors influencing variation in individual fitness.

Effects of 25 pharmaceutical compounds to Lemna gibba using a seven-day static-renewal test.

Abstract: Antibiotics are known to have antichloroplastic properties, but their effects on aquatic higher plants are virtually unknown. In order to address this issue, 25 pharmaceuticals, including 22 antibiotics, were assessed for phytotoxicity to the aquatic higher plant Lemna gibba. A 7-d static-renewal test was used, and plants were treated with 0, 10, 30, 100, 300, and 1,000 microg/L of pharmaceutical-containing growth media. Phytotoxicity was assessed using multiple growth and biochemical endpoints. Effective concentration (EC)50, EC25, and EC10 values as well as tests for significant differences between treatments and controls lowest-observed-effect concentration (LOECs) were calculated for each endpoint. Twelve different classes of antibiotics were assessed; however, only members of the fluoroquinolone, sulfonamide, and tetracycline classes of antibiotics displayed significant phytotoxicity. The most toxic members of each of these classes tested were lomefloxacin, sulfamethoxazole, and chlortetracycline, with wet weight EC25 values of 38, 37, and 114 microg/L, respectively. Injury symptoms were comparatively uniform and consistent among chemical classes while degree of phytotoxicity varied considerably. Both of these criteria varied markedly between classes. Wet mass was consistently the most sensitive endpoint above 100 microg/L; conversely, frond number was the most sensitive below 100 microg/L. Pigment endpoints were significantly less sensitive than growth endpoints.