RESUMEN
As human-caused extinctions and invasions accumulate across the planet, understanding the processes governing ecological functions mediated by species interactions, and anticipating the effect of species loss on such functions become increasingly urgent. In seed dispersal networks, the mechanisms that influence interaction frequencies may also influence the capacity of a species to switch to alternative partners (rewiring), influencing network robustness. Studying seed dispersal interactions in novel ecosystems on O'ahu island, Hawai'i, we test whether the same mechanisms defining interaction frequencies can regulate rewiring and increase network robustness to simulated species extinctions. We found that spatial and temporal overlaps were the primary mechanisms underlying interaction frequencies, and the loss of the more connected species affected networks to a greater extent. Further, rewiring increased network robustness, and morphological matching and spatial and temporal overlaps between partners were more influential on network robustness than species abundances. We argue that to achieve self-sustaining ecosystems, restoration initiatives can consider optimal morphological matching and spatial and temporal overlaps between consumers and resources to maximize chances of native plant dispersal. Specifically, restoration initiatives may benefit from replacing invasive species with native species possessing characteristics that promote frequent interactions and increase the probability of rewiring (such as long fruiting periods, small seeds and broad distributions).
Asunto(s)
Dispersión de Semillas , Ecosistema , Extinción Biológica , Humanos , Especies Introducidas , Dispersión de las PlantasRESUMEN
El Niño Southern Oscillation events (ENSO) and the subsequent opposite weather patterns in the following months and years (La Niña) have major climatic impacts, especially on oceanic habitats, affecting breeding success of both land and sea birds. We assessed corticosterone concentrations from blood samples during standardized protocols of capture, handling and restraint to simulate acute stress from 12 species of Galapagos Island birds during the ENSO year of 1998 and a La Niña year of 1999. Plasma levels of corticosterone were measured in samples collected at capture (to represent non-stressed baseline) and subsequently up to 1â¯h post-capture to give maximum corticosterone following acute stress, and total amount of corticosterone that the individual was exposed to during the test period (integrated corticosterone). Seabird species that feed largely offshore conformed to the brood value hypothesis whereas inshore feeding species showed less significant changes. Land birds mostly revealed no differences in the adrenocortical responses to acute stress from year to year with the exception of two small species (<18â¯g) that had an increase in baseline and stress responses in the ENSO year - contrary to predictions. We suggest that a number of additional variables, including body size and breeding stage may have to be considered as explanations for why patterns in some species deviated from our predictions. Nevertheless, comparative studies like ours are important for improving our understanding of the hormonal and reproductive responses of vertebrates to large scale weather patterns and global climate change in general.
Asunto(s)
Corteza Suprarrenal/metabolismo , Charadriiformes/fisiología , El Niño Oscilación del Sur , Islas , Estrés Fisiológico , Animales , Charadriiformes/sangre , Corticosterona/sangre , Ecuador , Femenino , Masculino , Modelos Biológicos , Lluvia , Restricción Física , Especificidad de la Especie , Temperatura , Factores de TiempoRESUMEN
Animals eavesdrop on other species to obtain information about their environments. Heterospecific eavesdropping can yield tangible fitness benefits by providing valuable information about food resources and predator presence. The ability to eavesdrop may therefore be under strong selection, although extensive research on alarm-calling in avian mixed-species flocks has found only limited evidence that close association with another species could select for innate signal recognition. Nevertheless, very little is known about the evolution of eavesdropping behaviour and the mechanism of heterospecific signal recognition, particularly in other ecological contexts, such as foraging. To understand whether heterospecific eavesdropping was an innate or learned behaviour in a foraging context, we studied heterospecific signal recognition in ant-following birds of the Neotropics, which eavesdrop on vocalizations of obligate ant-following species to locate and recruit to swarms of the army ant Eciton burchellii, a profitable food resource. We used a playback experiment to compare recruitment of ant-following birds to vocalizations of two obligate species at a mainland site (where both species are present) and a nearby island site (where one species remains whereas the other went extinct approx. 40 years ago). We found that ant-following birds recruited strongly to playbacks of the obligate species present at both island and mainland sites, but the island birds did not recruit to playbacks of the absent obligate species. Our results strongly suggest that (i) ant-following birds learn to recognize heterospecific vocalizations from ecological experience and (ii) island birds no longer recognize the locally extinct obligate species after eight generations of absence from the island. Although learning appears to be the mechanism of heterospecific signal recognition in ant-following birds, more experimental tests are needed to fully understand the evolution of eavesdropping behaviour.
Asunto(s)
Hormigas/fisiología , Conducta Alimentaria , Aprendizaje , Passeriformes/fisiología , Vocalización Animal , Animales , PanamáRESUMEN
Predation is an important selective pressure in natural ecosystems. Among non-human primates, relatively little is known about how predators hunt primate prey and how primates acquire adaptive responses to counteract predation. In this study we took advantage of the recent reintroduction of radio-tagged harpy eagles (Harpia harpyja) to Barro Colorado Island (BCI), Panama to explore how mantled howler monkeys (Alouatta palliata), one of their primary prey, acquire anti-predator defences. Based on the observation that harpies follow their prey prior to attack, and often call during this pursuit period, we broadcast harpy eagle calls to howlers on BCI as well as to a nearby control population with no harpy predation. Although harpies have been extinct from this area for 50-100 years, results indicate that BCI howlers rapidly acquired an adaptive anti-predator response to harpy calls, while showing no response to other avian vocalizations; howlers maintained this response several months after the removal of the eagles. These results not only show that non-human primates can rapidly acquire an alarm response to a newly introduced predator, but that they can detect and identify predators on the basis of acoustic cues alone. These findings have significant implications both for the role of learning mechanisms in the evolution of prey defence and for conservation strategies, suggesting that the use of 'probing' approaches, such as auditory playbacks, may highly enhance an a priori assessment of the impact of species reintroduction.
Asunto(s)
Alouatta/fisiología , Comunicación Animal , Águilas/fisiología , Conducta Predatoria , Animales , Geografía , Masculino , PanamáRESUMEN
With the growing influx of immigrants from the Dominican Republic entering the U.S. yearly, it is important for nurses to become familiar with their traditional health beliefs and health care experiences. The purpose of this study was: (a) to identify health beliefs of rural Dominicans and (b) to describe health care encounters between rural Dominicans and a visiting team of U.S. nurses. The data on health beliefs were collected in six focus groups and were analyzed using content analysis techniques. Health encounter data were collected from 693 Dominicans as they presented to mobile clinics for care. Findings from the focus group interviews suggested that health beliefs fall into two major categories: physical and spiritual/mystical. The most frequently occurring health problems, summaries of medications dispensed, treatments provided, referrals made, and health teaching information are presented.
Asunto(s)
Actitud Frente a la Salud/etnología , Conductas Relacionadas con la Salud/etnología , Conocimientos, Actitudes y Práctica en Salud , Servicios de Salud/estadística & datos numéricos , Salud Rural , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Niño , Preescolar , Diversidad Cultural , República Dominicana , Emigración e Inmigración , Femenino , Grupos Focales , Humanos , Lactante , Recién Nacido , Intercambio Educacional Internacional , Masculino , Persona de Mediana Edad , Enfermería Transcultural/educación , Estados UnidosRESUMEN
International labor migration has increased the day-to-day encounters of persons from different cultural groups. The concept of ethnicity, its historical development, its ambiguity, and its role in the interactions between persons of different cultural groups are explored. The arena of health care for migrants brings to the fore issues of providing culturally competent care. In an ideal world, all nursing care of migrants would be delivered by skilled transcultural nurses; but in the real world, this is not yet the case. A case study of a Mexican migrant woman and a non-Hispanic Midwestern nurse is used as a background for examining the role of ethnicity in determining care needs and expectations and for providing nurses with a perspective that can improve nurse-client collaboration.
Asunto(s)
Actitud Frente a la Salud/etnología , Emigración e Inmigración , Enfermería Holística , Americanos Mexicanos/psicología , Relaciones Enfermero-Paciente , Enfermería Transcultural , Femenino , Humanos , México/etnología , Persona de Mediana Edad , Evaluación de Necesidades , Estados UnidosRESUMEN
While use of nursing diagnoses has increased both in the United States and abroad, there have been few reports on the use and applicability of the diagnostic categories across culturally distinct populations. The authors report a preliminary study which compared the use of selected diagnostic categories in an American group and a Mexican group of nurses. Data indicate that nurses did not demonstrate consistency with one another in use of diagnoses either within each group or between groups. The authors caution that further study and documentation of how diagnoses are understood and used by practitioners is needed before widespread international or transcultural usage in encouraged.