Anther evolution: pollen presentation strategies when pollinators differ.

Male-male competition in plants is thought to exert selection on flower morphology and on the temporal presentation of pollen. Theory suggests that a plant's pollen dosing strategy should evolve to match the abundance and pollen transfer efficiency of its pollinators. Simultaneous pollen presentation should be favored when pollinators are infrequent or efficient at delivering the pollen they remove, whereas gradual dosing should optimize delivery by frequent and wasteful pollinators. Among Penstemon and Keckiella species, anthers vary in ways that affect pollen release, and the morphology of dried anthers reliably indicates how they dispense pollen. In these genera, hummingbird pollination has evolved repeatedly from hymenopteran pollination. Pollen production does not change with evolutionary shifts between pollinators. We show that after we control for phylogeny, hymenopteran-adapted species present their pollen more gradually than hummingbird-adapted relatives. In a species pair that seemed to defy the pattern, the rhythm of anther maturation produced an equivalent dosing effect. These results accord with previous findings that hummingbirds can be more efficient than bees at delivering pollen.

Association of knowledge, anxiety, and fear with adherence to follow up for colposcopy.

OBJECTIVES: To evaluate the association of pre-visit anxiety with pre- and post-visit knowledge, satisfaction, and adherence to colposcopy follow-up visits. METHODS: A group of 122 women presenting for colposcopy between July 1999 and May 2000 were studied. Immediately prior to their appointment, 98% of eligible patients participated in a self-administered questionnaire. Patients were sent a follow-up questionnaire within two weeks of the appointment. Statistical analyses included Chi-Square and Fisher's exact tests for categorical variables. RESULTS: The mean follow up was 112 days (SE 9.47). Although the mean fear score was 7.3 (SE 3, range 1-10) and mean anxiety score was 7.8 (SE 2.8, range 1-10), there was no significant association with pre-visit fear and adherence to follow up. Pre-evaluation knowledge was positively associated with fear, anxiety, post-visit knowledge, and adherence to follow up. CONCLUSIONS: Pre-visit intervention may improve adherence and reduce anxiety associated with colposcopy.