Genetic variation and constraints on the evolution of defense against spittlebug (Philaenus spumarius) herbivory in Mimulus guttatus.

Plants mediate carbon into most ecosystems and are thus under persistent attack by diverse enemies. The evolution of defense against such assaults will depend on the availability of genetic variation, as well as the costs and constraints on defense. We estimated the magnitude of genetic variation for defense against spittlebug (Philaenus spumarius) herbivory in Mimulus guttatus using a diallel cross-grown in a greenhouse. Except for flowering time, additive genetic variation for the plant traits we measured was negligible, regardless of herbivory environment. In contrast, nonadditive genetic variation contributed significantly to all plant traits measured. We found significant additive genetic variation among plants for biomass of adult spittlebugs, suggesting heritability for resistance to herbivory. The other putative resistance trait measured, spittlebug maturation time, was not significantly heritable. We found no evidence for significant genetic variation for tolerance to herbivory except for a small non-nuclear paternal contribution to tolerance for flower number. Additive genetic correlations indicated that more resistant plant genotypes (in terms of adult spittlebug biomass) were also smaller in the absence of spittlebugs, suggesting a potential cost of resistance to herbivory. We found no other significant genetic correlations indicating a cost of defense, nor did we find evidence for a tradeoff between resistance and tolerance to herbivory. Overall, these results suggest the future adaptive evolution of tolerance to spittlebugs in this population will be limited primarily by available genetic variation, whereas the future evolution of antibiosis resistance may be constrained by allocation costs of resistance.

Sexual dimorphism and fruit production in a dioecious understory tree, Ilex opaca Ait.

This study suggested that sexual selection is potentially an important factor in the maintenance of dioecy in the American holly, Ilex opaca (Aquifoliaceae). Sexual dimorphisms in flower production and phenology were highly significant in this understory tree. On average, individual males produced 7.4 times as many flowers as did female trees. Staminate flowers lasted only a single day, whereas pistillate flowers lasted 3-4 days, during which they showed no significant decline in their ability to produce fruit after pollination. Individual male trees opened their flower buds asynchronously during the season, maximizing the number of days they were in flower. Individual females opened their buds more synchronously, maximizing their floral display at one point in time. Females produced fruits in numbers that were somewhat less than proportional to their flower production. Fruit development was initiated from only 38.9% and 69.5% of pistillate flowers in 1987 and 1988, respectively. By the time of ripening, an average female had lost 62.3%, 24.3%, and 11.1% of its initial fruit crop in 1986, 1987, and 1988, respectively. The proportion of fruit lost in 1986 was independent of the number of fruit that initially began development. In 1988, artifically supplementing pollen to a large number of flowers failed to increase either fruit or seed production relative to control branches with unsupplemented flowers. This suggested that resource levels were likely more important than pollen availability in limiting female reproductive success. These observations on I. opaca were consistent with the expectations for a population in which male reproductive success continues to benefit from continued pollinator service and female reproductive success does not.

Anteroinferior Tibiofibular Ligament Injury: Not Just Another Ankle Sprain.

In brief: Ankle sprains that primarily involve the anteroinferior tibiofibular ligament are reportedly uncommon, but the authors have recently seen several such injuries in their clinic. These high ankle sprains usually are caused by forced lateral rotation with the foot in dorsiflexion. Edema and ecchymosis are generally minimal, with pain and tenderness over the distal anterior tibiofibular syndesmosis. Pain and disability can persist for weeks. Rehabilitation consists of range-of-motion exercises leading up to weight-bearing and often takes much longer than the initial symptoms might suggest.

Genetic variation and covariation for resistance and tolerance to Cucumber mosaic virus in Mimulus guttatus (Phrymaceae): a test for costs and constraints.

Genetic variation for resistance and tolerance to pathogens may be maintained by costs represented as genetic tradeoffs between these traits and fitness. The evolution of resistance and tolerance also may be constrained by negative genetic correlations between these defense systems. Using a complete diallel, we measured genetic variation and covariation for and among performance, resistance, and tolerance traits in Mimulus guttatus challenged with a generalist pathogen, Cucumber mosaic virus (CMV). Viral coat protein was detected by enzyme-linked immunosorbent assay (ELISA) in all inoculated plants, indicating that all plants were susceptible to infection, although the ELISA absorbance varied quantitatively across plants. Plants inoculated with CMV had significantly reduced aboveground biomass and flower production relative to controls, although date of first flower was unaffected by infection. All three of these performance traits showed moderate to high narrow-sense heritability (h2 = 0.32-0.62) in both inoculated and control plants. We found phenotypic variation for both tolerance of and resistance to our strain of CMV, but both displayed very low narrow-sense heritability (h2 < 0.03). We found no evidence of a trade-off between resistance and tolerance. We also found no evidence for a cost of resistance or tolerance. In fact, a significant genetic correlation suggested that plants that were large when healthy had the greatest tolerance when infected. Significant, positive genetic correlations found between performance of uninfected and infected plants suggested that selection would likely favor the same M. guttatus genotypes whether CMV is present or not.

Parent acceptability and feasibility of ADHD interventions: assessment, correlates, and predictive validity.

Examined variables related to parents' stated willingness to pursue treatment, and their actual adherence to treatment recommendations, for children with attention deficit-hyperactivity disorder (ADHD). Parents (87 mothers; 63 fathers) of 91 patients seen for evaluation at an outpatient ADHD clinic completed the ADHD Knowledge and Opinions Survey-Revised (AKOS-R). A factor analysis of the AKOS-R revealed three relevant factors: Counseling Acceptability, Medication Acceptability, and Counseling Feasibility. Externalizing problems were positively related to parents' Counseling Acceptability ratings, while parents' ADHD knowledge was positively related to their Medication Acceptability ratings. However, Counseling Acceptability, Counseling Feasibility, and Medication Acceptability scores at intake failed to predict parents' pursual of recommended counseling and medication at follow-up. Association between treatment acceptability and adherence might be enhanced by assessing treatment acceptability at multiple points during the assessment and treatment process.