Plants as a realized niche for Listeria monocytogenes

Listeria monocytogenes is a human pathogen. It is the causative agent of listeriosis, the leading cause of bacterial-linked foodborne mortality in Europe and elsewhere. Outbreaks of listeriosis have been associated with the consumption of fresh produce including vegetables and fruits. In this review we summarize current data providing direct or indirect evidence that plants can serve as habitat for L. monocytogenes, enabling this human pathogen to survive and grow. The current knowledge of the mechanisms involved in the interaction of this bacterium with plants is addressed, and whether this foodborne pathogen elicits an immune response in plants is discussed.

REALIZED ECOLOGICAL NICHE OF THE MEXICAN SPOTTED OWL (Strix occidentalis lucida) IN MEXICO

Objective: To characterize the realized niche of the Mexican spotted owl (Strix occidentalis lucida) and compare the environmental values it uses within the Mexican physiographic provinces.Design/methodology/approach: The environmental temperature variables (n =7), precipitation (n = 7) and elevation (n = 1) were extracted from 79 unique occurrences sites of S. o. lucida. These values were grouped by physiographic provinces: Sierra Madre Occidental (n = 59), Sierra Madre Oriental (n = 13) and Transversal Neovolcanic Belt (n = 6). The climate and elevation of these sites were described and compared via non-parametric Kruskal-Wallis and Bonferroni-Dunn tests (P ? 0.05).Results: The presences of the spotted owls were both, dispersed and focallydistributed, over the geographic space in Mexico. The temperature and elevation variables have similar characteristics in the assessed physiographic provinces. To be noted, the precipitation variables showed significant differences among sites.Limitations on study/implications: This study describes the environmental characteristics of the realized niche of the Mexican spotted owl; however, it isnecessary to investigate other habitat variables at a smaller scale. Findings/conclusions: The temperature and elevation environmentalcharacteristics of the ecological niche of the Mexican spotted owl was similar between physiographic provinces.

Seasonality, niche management, and vertical migration in landscapes of relief

Landscapes of vertical relief, such as mountains and continental slopes, intensify ecological and climatological variation within narrow spatial windows. Seasonal vertical migrants exploit this variation during their residence in, and movements between, vertically stratified seasonal ranges. Animals in terrestrial, marine, and even human-ecological systems undergo similar patterns of seasonal vertical movements. The diversity of arenas in which vertical migration evolved lends insight to the factors promoting seasonal use of landscapes of relief. Because animals must contend with both endogenous circannual rhythms and exogenous environmental seasonality, vertical migrants may be sensitive to inconsistent change across stratified seasonal ranges under climate change. To better understand how ongoing and future climatic and environmental changes are likely to impact vertical migrants, we examine vertical migration in the context of niche tracking and niche switching. Whereas niche trackers minimize variation in realized environmental conditions throughout their seasonal movements, niche switchers undergo seasonal transitions in realized niche space. These strategies mediate the relationship between migrants and their changing environment, and can be used to forecast impacts of future change and effectively conserve systems of vertical migration. Niche tracking may be hindered by inconsistent or unpredictable environmental change along a single niche axis across strata, while niche switching may be sensitive to incongruous spatiotemporal change across factors. We suggest that climate change will affect seasonal patterns in vertical environments discontinuously across time, space, and strata, and that vertical migrants are likely to face additional anthropogenic threats that interact with environmental seasonality. Conservation of vertical migrants should prioritize the availability of, and facilitate movement between, stratified seasonal ranges.

Spread Risk Assessment of Invasive Axis Deer using Bioclimatic Niche Models

Ecological niche models (ENM) calibrated with data from native and invaded ranges are useful tools to manage biological invasions and can be challenged by niche shifts and non-equilibrium processes. We modeled the extent of the potential invasion by the axis deer (Axis axis) worldwide, testing the reciprocal hypotheses of niche conservatism and shift. We quantified niche overlap on the multivariate climatic space and modeled climatic realized niche based on detailed field information. We showed that the axis deer shifted its realized niche after the invasion. We rejected the niche equivalency hypothesis. Most of the climatic niche available in invaded areas is contained in the native climatic niche. Non-equilibrium between native and invasive niches of the axis deer was confirmed due to a large number of unfilled areas in invaded regions. Our projections predict that the most significant regions suitable for the axis deer are located in tropical and subtropical climates around the equator and the southern hemisphere, mostly in the Neotropics.

Senecio inaequidens (South African ragwort).

S. inaequidens is a herbaceous perennial considered native to South Africa. It has spread rapidly in North and Central Europe following its accidental introduction from South Africa in wool exports. In the absence of rigorous phytosanitary controls, it is very likely to spread further along roads and railways. As its present realized niche differs to a large extent from its equilibrium niche (Vacchiano et al., 2013), it has to be expected that the species will spread into grasslands and pastures in the near future. S. inaequidens is a prolific achene producer, has vigorous growth and is toxic. Its economic impacts are currently minimal, and so far, no environmental impacts have been observed; however, due to its toxicity, its potential to spread into arable land should be considered a serious threat for cattle and human health. This species should in no case be considered for cultivation, even though its usefulness for health care (for example) has been demonstrated.

The influence of habitat preference on longitudinal population composition and distribution of Groupers (Serranidae) in Chumbe Island Coral Park, Zanzibar, Tanzania

A survey of six common grouper (Serranidae) species was conducted on both the western protected and eastern unprotected reefs around Chumbe Island, Zanzibar. Species, estimated maturity, and habitat were recorded using standardized categories. Fundamental niche and general habitat preference were extrapolated based on observed realized niche and qualified based on substrate, depth, slope position, and general reef region. Taking habitat preference into account, abundance and biomass density of serranid populations were compared between locations on the reef in order to best account for how habitat influences distribution and population health. The results of this study provide depth to previous research on the protected reef and indicate noteworthy shifts in population composition between 2014 and 2018 that favour species with less specified habitat preference, such as Aethaloperca rogaa and Cephalopholis argus. Surveys of Chumbe’s nearby unprotected eastern reef indicate low levels of species abundance, which this study hypothesizes is the result of inappropriate habitat structure, increased fishing pressure, and decreased population health within the MPA. Ultimately, this study suggests that MPAs do not protect all species equally, and habitat preference must be taken into account when assessing MPA effectiveness at protecting different species. Indeed, especially as serranid habitat faces continued degradation, serranid conservation will depend even more on protection of each species’ preferred habitat in coral systems. As such, assessing serranid populations as a whole fails to capture the changes in population distribution and composition that is occurring between species, which may be more indicative of shifts and disturbances in the ecosystem.

Estimating the fundamental niche: accounting for the uneven availability of existing climates

In the last years, studies that question important conceptual and methodological aspects in the field of ecological niche modeling (and species distribution modeling) have cast doubts on the validity of the existing methodologies. Particularly, it has been broadly discussed whether it is possible to estimate the fundamental niche of a species using presence data. Although it has being identified that the main limitation is that presence data come from the realized niche, which is a subset of the fundamental niche, most of the existing methods lack the ability to overcome it, and then, they fit objects that are more similar to the realized niche. To overcome this limitation, we propose to use the region that is accessible to the species (based on its dispersal abilities) to determine a sampling distribution in environmental space that allow us to quantify the likelihood of observing a particular environmental combination in a sample of presence points. We incorporate this sampling distribution into a multivariate normal model (Mahalanobis model) by creating a weight function that modifies the probabilities of observing an environmental combination in a sample of presences as a way to account for the uneven availability of environmental conditions. We show that the parameters of the modified, weighted-normal model can be approximated by a maximum likelihood estimation approach, and used to draw ellipsoids (confidence regions) that represent the shape of the fundamental niche of the species. We illustrate the application of our model with two worked examples: (i) using presence points of an invasive species and an accessible area that includes only its native range, to evaluate whether the fitted model predicts confirmed establishments of the species outside its native range, and (ii) using presence data of closely related species with known accessible areas to exhibit how the different dispersal abilities of the species constraint a classic Mahalanobis model. Taking into account the distribution of environmental conditions that are accessible to the species indeed affected the estimation of the ellipsoids used to model their fundamental niches.