Biomedical subjects

C M Caruso

Publications and source records attributed to C M Caruso.

3 recordsLinked to original sources

PubMed2000

Competition for pollination influences selection on floral traits of Ipomopsis aggregata.

Although rarely tested, it is often assumed that interspecific competition results in the divergence of traits related to resource use. Using a plant-pollinator system as a model, I tested the prediction the presence of a competitor for pollination influences the strength and/or direction of pollinator-mediated selection on floral traits. I measured phenotypic selection via female fitness on five floral traits of Ipomopsis aggregata in seven populations. Four contained only conspecifics (I only) and three also contained the competitor Castilleja linariaefolia (C + I). Directional selection via fruits/plant and conspecific pollen deposited/flower on corolla length was positive and significantly stronger in C + I populations. This difference in selection was apparently driven by interpopulation variation in the degree to which reproduction of I. aggregata was pollen limited. Consistent with expectations of interspecific competition, I. aggregata plants in C + I populations received less conspecific pollen per flower and set fewer seeds per fruit and fruits per plant than those in I only populations. Ipomopsis aggregata's corollas were also significantly longer in C + I populations, suggesting that there had been a response to a similar selective regime in past generations. Phenotypic correlations between corolla length and width, which determine the variation in I. aggregata's flower shape, were significantly weaker in C + I populations. These data suggest that competition for pollination can influence the strength of selection on and patterns of correlations among floral traits of I. aggregata. If I. aggregata populations with and without competitors for pollination are linked by gene flow, then measuring selection in competitive and noncompetitive environments maybe necessary to accurately predict how floral traits will evolve.

Biological Evolution↗

PubMed1999

Pollination of Ipomopsis aggregata (Polemoniaceae): effects of intra- vs. interspecific competition.

Although plants may simultaneously experience intra- and interspecific competition for pollination, their relative strength has rarely been experimentally evaluated. Yet because intra- and interspecific competition can be caused by different mechanisms, their effect on the ecology and evolution of plants may differ. To determine the relative strength of intra- and interspecific competition for pollination, I manipulated the presence of heterospecifics and density of conspecifics using Ipomopsis aggregata as the focal species. All plots contained I. aggregata and Castilleja linariaefolia, but C. linariaefolia inflorescences were removed from half of the plots to create the heterospecifics-absent treatment. Within each plot, all I. aggregata inflorescences were removed from a 5-m radius around a focal plant to create a low conspecific density experimental unit, and a group of 12 I. aggregata plants/1 m(2) was designated as a high conspecific density unit. Conspecific pollen deposition was reduced when C. linariaefolia was present but was not influenced by I. aggregata density. Although seed set per fruit was reduced by 17% when C. linariaefolia was present, it was not significantly influenced by either treatment. Interspecific competition for pollination is stronger than intraspecific competition in the I. aggregata-C. linariaefolia system, but neither process appears to influence plant fitness.

Journal Article↗

PubMed1992

Strengthening physical self-perceptions through exercise.

Two studies examined the effects of physical activity/exercise on physical self-perceptions, self-efficacy, body satisfaction, fitness and relationships among these variables. In study 1, 34 female undergraduates participated in a 10-week exercise/activity program. Participants were selected from existing classes forming a weight training, aerobic exercise and activity control group. Results revealed changes in physical self-perceptions, strength, and body composition over the 10-weeks. Improvements in physical self-perceptions and fitness occurred independent of exercise/activity group. Groups differed in the perceived importance attached to physical self-perceptions. Correlations among the measures revealed relationships among physical self-perceptions, body satisfaction, global self-esteem, and fitness. In study 2, we hypothesized that weight training would have a greater effect on physical self-perceptions and body image perceptions than physical education activity classes. Thirty-seven males and 28 females were selected from existing classes forming a weight training and activity group. Results revealed no significant changes in physical self-perceptions, body image, or global self-esteem over the 10-week program, while strength and physical self-efficacy improved. Correlations among measures from both studies offer preliminary support for Sonstroem and Morgan's model for the examination of self-esteem in exercise settings.

Adolescent↗