Identifying demand parameters in the presence of unobservables: A combined revealed and stated preference approach

• ALTHOUGH MOST ACADEMIC programs use hospital-based sites for perioperative clinical experiences, the exponential growth in the number of ambulatory surgery centers (ASCs) and the increased variety of procedures performed in these settings make ASCs excellent venues for student learning experiences.• NURSING STUDENTS in one program in Florida have the opportunity to take a perioperative practicum designed to allow them to learn about all aspects of patient care and administrative functions in ASCs.• THE ASC PRACTICUM EXPERIENCE is popular with students and staff members alike, and ASC administrators are seeking ways to increase the number of students in the program in an effort to attract new graduates to ASCs. AORN J 84 (August 2006) 219–232. © AORN, Inc, 2006.

Postcopulatory sexual selection favours intrinsically good sperm competitors

We used guppies to study repeatability in sperm competitiveness and postcopulatory sexual selection on male ornamentation. In a block design involving 25 pairs of males, artificial insemination was used to mate each pair (A and B) to four unrelated females—two that were mated with the combined ejaculates of both males (sperm-competition treatment) and two receiving sperm from each of the two males individually (single-male treatment). Our analysis revealed significantly repeatable patterns of paternity across females in the sperm-competition treatment, suggesting that certain males are intrinsically better sperm competitors than others, irrespective of female identity. Next, we compared mean brood success (number of offspring per brood) between sperm competition and single-male treatments. We found no significant effect of treatment on female fecundity, suggesting that the previously reported direct benefits of polyandry in this species may be due to factors such as differential maternal effects or differences in the number of inseminated sperm between treatments. Our artificial insemination assay was designed to control both factors. Finally, we determined whether variation in relative paternity was random with respect to male phenotype. Unlike previous work on Trinidadian populations, we found no significant relationship between male sexual ornamentation and sperm competitiveness in the focal population.     

Lack of innate preference for morph and species identity in mate-searching <Emphasis Type="Italic">Enallagma</Emphasis> damselflies

Insect mate recognition is often viewed as stereotypic, innate, and species-specific. However, male damselflies can learn to identify female-specific color morphs as potential mates. A suite of male mimicry hypotheses assume that heteromorphic females, which differ from males in color pattern, are more easily recognized as “female” and thus lack the inherent, anti-harassment advantage that the more male-like signal provides for andromorphs. Using two measures of male preference, we investigated whether naïve males have a preexisting sensory bias for a given morph color in Enallagma civile, a species that appeared to exhibit extreme plasticity in morph expression across generations within a breeding season. E. civile males raised in the absence of females exhibited no preference for either morph, whereas males raised with one female type exhibited a learned sensory bias for that morph. Male Enallagma also lacked a bias toward conspecific females over a congeneric sister species. In a naturally naïve population of Enallagma ebrium, males reacted sexually to both morphs of Enallagma hageni as often as they did to conspecific females, whose thoracic spectra were nearly identical with those of E. hageni. Moreover, despite the similar thoracic spectra of males and andromorphs, both of which reflected UV, males rarely reacted sexually to other males. Our results falsified implicit assumptions of male mimicry hypotheses, supported learned mate recognition, and suggested a scenario for speciation via sexual conflict.     

Risk management and integrated assessment

Integrated Assessment (IA) is the pursuit of a research program generated by the limitations of traditional forms of risk management. This claim can be justified by the following argument. Over the last decades, analysts and practitioners have brought to maturity a large array of tools for risk management. Most of them rely on combining judgments of utility with judgments of probability. This is the approach of the Rational Actor Paradigm (RAP). With many environmental problems, however, RAP‐based tools have run into considerable practical and theoretical difficulties. In response to these difficulties, a series of alternative approaches to practical risk management and to the theoretical understanding of risk have been elaborated. They try to embed the rational choices of individual actors studied by RAP into a broader framework of social rationality. This task can be approached by distinguishing situations where an actor holds unambiguous judgments of preference and probability from situations characterized by ambivalent judgments. RAP can handle the former, but not the latter. Problems whose management requires a combination of widely differing scientific disciplines are especially likely to involve ambivalent judgments of probability. The study of such problems constitutes the research program of integrated assessment. It involves three main tasks: developing IA models which can represent ambivalent expectations and evaluations, developing IA models which use such representations to study non‐marginal changes of social systems, and developing procedures of participatory IA which enable researchers to engage in an iterative exchange with various stakeholders. This revised version was published online in August 2006 with corrections to the Cover Date.     

Heterogeneous preferences for recreation-oriented management in commercial forests: the role of citizens’ socioeconomic characteristics and recreational profiles

The management of forests for multiple benefits, such as recreational services alongside timber production, can greatly benefit from the knowledge of public preferences for management-related forest attributes. This paper investigates citizens’ recreational use and preferences for recreation-oriented management in the case of state-owned commercial forests in Finland using data from a choice experiment study. We focus on attributes related to the typical management practices applied to enhance recreation: scenic buffer zones along waters, game bird habitats, and the quality of scenery along hiking trails. Recreational use and its frequency were found to be related to citizens’ background and specific outdoor activities. The scenic buffer zones were the most important attribute to the citizens. While the recreation-enhancing practices were generally valued, respondent segments with distinct preferences were found. Preference heterogeneity was related to citizens’ socioeconomic characteristics and recreational profiles.     

Condition dependence of sexual attractiveness in the bank vole

The capture of genetic variation by sexual traits due to their condition dependence is hypothesized to underlie the genetic benefits of mate choice. Here, we investigate condition dependence of sexual attractiveness of bank vole Myodes glareolus males by manipulating their diet during the period of maturation. We find that reducing diet quality negatively affected both male mating success and development of preputial glands used in sexual signaling. Preputial glands showed stronger condition dependence than other organs measured (testes, heart, intestines). In contrast to mating success, male dominance was not significantly affected by diet manipulation and was not correlated with male mating success. Thus, our results support condition dependence of sexual attractiveness but not of intrasexual competitiveness.     

Indirect fitness benefits are not related to male dominance in a killifish

Recent theoretical and empirical studies have shown that male dominance is often at odds with female mate preference and that indirect (genetic) benefits of mate choice may not be related to male dominance. We tested whether female preference corresponded to male dominance and whether mating with dominant males conveyed benefits to offspring fitness in a small freshwater fish, the African annual killifish Nothobranchius korthausae (Cyprinodontiformes), a species without parental care. The experimental design used controlled for the effect of male age, possibility of sperm and egg depletion, and accounted for a potential that females express their preference through maternal effects by manipulation of egg mass during ovulation. By sequentially mating females with males of known dominance, we found that female N. korthausae showed no mate preference in terms of egg numbers deposited with respect to male dominance or body size and no congruent mate preference to specific males was detected. However, males sired offspring with consistently higher hatching success and the effect was repeatable across individual females. Thus, some males provided females with indirect benefits related to additive genetic quality (“good genes”) and expressed via increased hatching rate, but this benefit was not related to male dominance status or body size.     

Odour-based species recognition in two sympatric species of sac-winged bats (<Emphasis Type="Italic">Saccopteryx bilineata,S. leptura)</Emphasis>: combining chemical analyses,behavioural observations and odour preference tests

Combining chemical analysis and odour preference tests, we asked whether two closely related sympatric species of sac-winged bats use odour for species recognition. Males of the two sister species Saccopteryx bilineata and Saccopteryx leptura have pouches containing an odoriferous liquid in their antebrachial wing membrane, which is used in S. bilineata during courtship displays. Although both species occasionally share the same daytime roosts and are morphologically similar, there is no evidence for interbreeding. We compared the production and composition of the wing sac odorant in male S. leptura and S. bilineata and performed odour preference tests with female S. bilineata. Similar to male S. bilineata, male S. leptura cleansed and refilled their wing sacs with secretions, but they spent more time each day in doing so than male S. bilineata. Chemical analysis by gas chromatography and mass spectrometry revealed that male Saccopteryx carried species-specific scents in their wing sacs. Binary choice tests confirmed that female S. bilineata preferred the wing sac scents of male S. bilineata to those of the sister species, suggesting that the species specificity of male wing sac scents maintain the pre-mating isolation barrier between these closely related species.     

Sexual cannibalism facilitates genital damage in <Emphasis Type="Italic">Argiope lobata</Emphasis> (Araneae: Araneidae)

Sperm competition is a potent driving force in evolution leading to a remarkable variety of male adaptations that prevent or reduce fertilization by rivals. An extraordinary defensive strategy against sperm competition has evolved in a number of web spiders where males break off parts of their paired genitalia in order to obstruct the copulatory openings of females (mating plug). A recent comparative analysis on the family level reports that genital damage is most frequent in species with sexual cannibalism although, as yet, a functional association between sexual cannibalism and genital damage has not been found. Using the moderately sexually cannibalistic orb-web spider Argiope lobata, we show for the first time that males cannibalized during their first copulation damaged their pedipalps with significantly higher probability (74%) than males that escaped (15%). Of all males that damaged their genitalia, 44% were able to place a genital fragment inside the copulatory opening of the female, resulting in a relatively low total plugging rate of 14%. Successful obstruction of the female copulatory opening reduced the share of paternity of subsequent males (P ₂ = 0.06%), thus, indicating that genital damage may have evolved as a response to sperm competition in this species as well. However, the low incidence of successful plugging and the strong relationship between sexual cannibalism and genital damage suggest that apart from paternity protection, the nature of genital damage in A. lobata is further shaped by sexual conflict or cryptic female choice.     

Experience counts: females favor multiply mated males over chemically endowed virgins in a moth (<Emphasis Type="Italic">Utetheisa ornatrix</Emphasis>)

Determining the factors that affect male mating success is essential to understanding how sexual selection operates, including explanations of the adaptive value of female preferences and how variation in male traits is maintained in a population. Although females may appear to choose males based on a single parameter, female mate choice is often a complex series of assessments of male quality that can only be revealed through manipulation of multiple male traits. In the moth Utetheisa ornatrix (Lepidoptera: Arctiidae), females have been shown to judge males primarily on their production of a courtship pheromone, hydroxydanaidal, derived from defensive chemicals acquired as larvae. Recent work, however, suggested that other factors, including prior mating experience by males, may also influence the outcome of precopulatory interactions with females. I ran mating trials with one female and two males to determine whether there were any differences in male mating success based on their prior exposure to females, mating experience, and time between matings. Previously mated males were favored over virgins when both males lacked the pheromone, but courting experience and mating interval did not explain these differences in male mating success. Furthermore, multiply mated males lacking the pheromone were favored over virgin males that produced the pheromone, thus reversing the commonly observed trend of female precopulatory bias towards males with higher levels of the pheromone. These results demonstrate that males with mating experience can secure copulations despite deficiencies in the pheromone, and I provide possible mechanisms and discuss their implications regarding sexual selection.