Background Mepraia gajardoi and Mepraia spinolai are endemic triatomine vector species of Trypanosoma cruzi, a parasite that causes Chagas disease. These vectors inhabit arid, semiarid and Mediterranean areas of Chile. Mepraia gajardoi occurs from 18° to 25°S, and M. spinolai from 26° to 34°S. Even though both species are involved in T. cruzi transmission in the Pacific side of the Southern Cone of South America, no study has modelled their distributions at a regional scale. Therefore, the aim of this study is to estimate the potential geographical distribution of M. spinolai and M. gajardoi under current and future climate scenarios. Methods We used the Maxent algorithm to model the ecological niche of M. spinolai and M. gajardoi, estimating their potential distributions from current climate information and projecting their distributions to future climatic conditions under representative concentration pathways (RCP) 2.6, 4.5, 6.0 and 8.5 scenarios. Future predictions of suitability were constructed considering both higher and lower public health risk situations. Results The current potential distributions of both species were broader than their known ranges. For both species, climate change projections for 2070 in RCP 2.6, 4.5, 6.0 and 8.5 scenarios showed different results depending on the methodology used. The higher risk situation showed new suitable areas, but the lower risk situation modelled a net reduction in the future potential distribution areas of M. spinolai and M. gajardoi. Conclusions The suitable areas for both species may be greater than currently known, generating new challenges in terms of vector control and prevention. Under future climate conditions, these species could modify their potential geographical range. Preventive measures to avoid accidental human vectorial transmission by wild vectors of T. cruzi become critical considering the uncertainty of future suitable areas projected in this study.

Species climate requirements are useful for predicting their geographic distribution. It is often assumed that the niche requirements for invasive plants are conserved during invasion, especially when the invaded regions share similar climate conditions. California and central Chile have a remarkable degree of convergence in their vegetation structure, and a similar Mediterranean climate. Such similarities make these geographic areas an interesting natural experiment for testing climatic niche dynamics and the equilibrium of invasive species in a new environment. We tested to see if the climatic niche of Eschscholzia californica is conserved in the invaded range (central Chile), and we assessed whether the invasion process has reached a biogeographical equilibrium, i.e., occupy all the suitable geographic locations that have suitable conditions under native niche requirements. We compared the climatic niche in the native and invaded ranges as well as the projected potential geographic distribution in the invaded range. In order to compare climatic niches, we conducted a Principal Component Analysis (PCA) and Species Distribution Models (SDMs), to estimate E. californica's potential geographic distribution. We also used SDMs to predict altitudinal distribution limits in central Chile. Our results indicated that the climatic niche occupied by E. californica in the invaded range is firmly conserved, occupying a subset of the native climatic niche but leaving a substantial fraction of it unfilled. Comparisons of projected SDMs for central Chile indicate a similarity, yet the projection from native range predicted a larger geographic distribution in central Chile compared to the prediction of the model constructed for central Chile. The projected niche occupancy profile from California predicted a higher mean elevation than that projected from central Chile. We concluded that the invasion process of E. californica in central Chile is consistent with climatic niche conservatism but there is potential for further expansion in Chile.

BackgroundHantavirus pulmonary syndrome (HPS) is an infection endemic in Chile and Argentina, caused by Andes hantavirus (ANDV). The rodent Oligoryzomys longicaudatus is suggested as the main reservoir, although several other species of Sigmodontinae are known hosts of ANDV. Here, we explore potential ANDV transmission risk to humans in southern South America, based on eco-epidemiological associations among: six rodent host species, seropositive rodents, and human HPS cases.MethodsWe used ecological niche modeling and macroecological approaches to determine potential geographic distributions and assess environmental similarity among rodents and human HPS cases.ResultsHighest numbers of rodent species (five) were in Chile between 35° and 41°S latitude. Background similarity tests showed niche similarity in 14 of the 56 possible comparisons: similarity between human HPS cases and the background of all species and seropositive rodents was supported (except for Abrothrix sanborni). Of interest among the results is the likely role of O. longicaudatus, Loxodontomys micropus, Abrothrix olivaceus, and Abrothrix longipilis in HPS transmission to humans.ConclusionsOur results support a role of rodent species’ distributions as a risk factor for human HPS at coarse scales, and suggest that the role of the main reservoir (O. longicaudatus) may be supported by the broader rodent host community in some areas.Electronic supplementary materialThe online version of this article (10.1186/s12942-018-0142-z) contains supplementary material, which is available to authorized users.

In this study, we compared demographic responses of Eschscholzia californica populations located at different altitude, under the basic assumption that altitudinal gradients impose environmental limitation to the spread at the upper edge of the gradient. We detected significant differences among populations either in terms of life history attributes and the finite rate of increase. In general, coastal population expressed higher finite population rates than mountain populations, although these differences were not statistically significant. Mountain populations (Corral Quemado and Farellones) expressed a finite population rate not significant different of 1. These result suggest that at the upper front of invasion the species is in a demographic equilibrium because in spite of we detected a higher plant fecundity, there exist ecological constraints a seed stage level. We proposed to address more specific studies assessing from one hand, seed movement from lower altitudes and the efficiency of domestic cattle as biotic vector; we also propose to examine the feasibility of this species to establish positive interactions with cushion plants, and therefore to expand its geographic range due to this facilitation effect. KEYWORDS:Populations, invasions, heterogeneity, demographic matrix. RESUMENEn este estudio comparamos las respuestas demográficas de las poblaciones de Eschscholzia californica ubicadas a diferentes altitudes, bajo el supuesto básico de que los gradientes altitudinales imponen limitaciones a la invasión. Se detectaron diferencias significativas entre las poblaciones, ya sea en términos de atributos de la historia de vida y tasa finita de crecimiento. En general, las poblaciones costeras expresaron mayores tasas de crecimiento que las poblaciones de montaña, aun cuando éstas no fueron estadísticamente significativas. Las poblaciones de montaña (Corral Quemado y Farellones) fueron las únicas que mostraron una tasa de crecimiento similar a 1. Estos resultados sugieren que las poblaciones ubicadas en el frente superior de invasión estarían en un equilibrio demográfico debido a que aun cuando se detectó una elevada fecundidad, existen restricciones ecológicas a nivel de las semillas. Proponemos hacer estudios más específicos para evaluar un posible movimiento de semillas desde altitudes más bajas y la eficiencia del ganado doméstico como vector transportador de estas semillas; proponemos también examinar la posibilidad que tiene esta planta de establecer interacciones positivas con las plantas en cojín, ubicadas a mayores alturas y, por lo tanto, ampliar su rango altitudinal debido a este efecto de facilitación.

Fotoblastismo negativo en la especie invasora Eschscholzia californica Cham. (Papaveraceae): Patrones de variación altitudinal en el rango nativo e introducido ABSTRACT Negative photoblastism is defined as the inhibitory effect of light on seed germination. This effect can be modulated by abiotic variables, such as temperature, light condition and water potential. This conditions change notoriously at higher altitudes, could promote differentiations in the photoblastic response among populations. Also, this physiological attribute poses an interesting conflict for plant regeneration, because prevents seed germination on the soil surface, however, it can also to reduce the mortality of seeds germinants in unsuitable conditions and consequently, seedling mortality. Eschscholzia californica is one of the few species with negative photoblastism and it is invasive in Chile, growing primarily in open and disturbed places. Some invasive species have the potential to adapt their morphological and ecophysiological characteristics faced to new environmental conditions. In this study, we examined variation in negative photoblastism between populations from central Chile (invasive) and California (native) located at the extremes of their altitudinal distribution. We used common garden experiments where seeds from different origins were germinated under controlled lab condition in Chile. If negative photoblastism is conserved, we would see similar responses among seeds original from this climatic analogues regions. Also, we evaluated whether seed burial increases seed germination of this species as a mechanism for escaping the intense luminosity at the soil surface, by planting seeds at different soil depths. For this experiment, we expected an increase of germination at higher soil depth. The results indicate no differences in negative photoblastism between Chilean and Californian populations. A significant variation across altitudinal range in California suggests the existence of genetic differentiation in the native region, however, the absence of differences across the altitudinal range in Chile suggests trait conservatism at local scale. Seed germination was zero at the soil surface and increased when seeds were experimentally buried, suggesting that negative photoblastism is inhibited. Three possible explanations are given to explain the pattern of establishment of E. californica despite having negative photoblastism. This is a fairly specialist trait, related with Mediterranean climates and does not explain by itself the invasiveness described for this specie. In any case, is clear that more studies are necessary to disentangle the adaptive value of this physiological trait. RESUMENEl fotoblastismo negativo es definido como el efecto inhibitorio de la luz sobre la germinación de las semillas. Este efecto puede ser modulado por variables abióticas, tales como temperatura, condición lumínica y potencial hídrico. Estas condiciones cambian notoriamente a mayores altitudes, pudiendo promover diferenciación en la respuesta f...

In Chile, all necrotic arachnidism is attributed to the Chilean recluse spider Loxosceles laeta (Nicolet) (Araneae: Sicariidae). It is predated by the spitting spider Scytodes globula (Nicolet) (Araneae: Scytodidae). The biology of each of these species is not well known and it is important to clarify their distributions. The aims of this study are to elucidate the variables involved in the niches of both species based on environmental and human footprint variables, and to construct geographic maps that will be useful in estimating potential distributions and in defining a map of estimated risk for loxoscelism in Chile. Loxosceles laeta was found to be associated with high temperatures and low rates of precipitation, whereas although S. globula was also associated with high temperatures, its distribution was associated with a higher level of precipitation. The main variable associated with the distribution of L. laeta was the human footprint (48.6%), which suggests that this is a highly invasive species. Similarly to other species, the distribution of L. laeta reaches its southern limit at the Los Lagos region in Chile, which coincides with high levels of precipitation and low temperatures. The potential distribution of L. laeta in Chile corresponds to the distribution of cases of loxoscelism.

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RESUMENRealizamos un experimento de laboratorio para evaluar el efecto de la luz blanca en la germinación de cinco taxa de Eriosyce subgen. Neoporteria. Todas las taxa germinaron profusamente con presencia de luz, mientras que en oscuridad casi no se registró germinación. Se discute que este rasgo fi siológico podría ser una respuesta conservada en el grupo Neoporteria.