Spatial point pattern analysis identifies mechanisms shaping the skin parasite landscape in Leishmania donovani infection

Increasing evidence suggests that infectiousness of hosts carrying parasites of the Leishmania donovani complex, the causative agents of visceral leishmaniasis, is linked to parasite repositories in the host skin. This is particularly true for asymptomatic to moderately symptomatic hosts with no or minimally detectable parasitemia. However, a detailed description of the dispersal and dispersion of parasites and parasitized host phagocytes in the skin is still lacking. Here, we combined image analysis with spatial point pattern models borrowed from ecology, providing a new route to predicting modes of skin parasite dispersal and characterizing their dispersion. Our results suggest that, after initial parasite seeding in the skin, parasites form self-propagating networks of parasite patch clusters in the skin that may contribute to parasite outward transmission. This combination of imaging and ecological pattern analysis to identify mechanisms driving the skin parasite landscape offers new perspectives on parasitism by Leishmania donovani and may also be applicable to elucidating the behavior of other intracellular tissue-resident pathogens.

Quantifying pyrodiversity and its drivers

Pyrodiversity or variation in spatio-temporal fire patterns is increasingly recognized as an important determinant of ecological pattern and process, yet no consensus surrounds how best to quantify the phenomenon and its drivers remain largely untested. We present a generalizable functional diversity approach for measuring pyrodiversity, which incorporates multiple fire regime traits and can be applied across scales. Further, we tested the socioecological drivers of pyrodiversity among forests of the western United States. Largely mediated by burn activity, pyrodiversity was positively associated with actual evapotranspiration, climate water deficit, wilderness designation, elevation and topographic roughness but negatively with human population density. These results indicate pyrodiversity is highest in productive areas with pronounced annual dry periods and minimal fire suppression. This work can facilitate future pyrodiversity studies including whether and how it begets biodiversity among taxa, regions and fire regimes.

Spatio-temporal variability of amphipod assemblages associated with rhodolith seabeds

Rhodolith seabeds are habitats underpinned by free-living calcareous macroalgae. We partitioned the relevance of the scale of temporal (four seasons throughout two successive years) and spatial (three depth strata: 18, 25 and 40m) variation on the diversity, structure and abundance of amphipod assemblages living in rhodolith seabeds from Gran Canaria Island. In total, 3996 individuals, belonging to 32 taxa, were identified. Multivariate analyses showed consistent differences in assemblage structure among seasons and depths; more diverse and abundant amphipod assemblages were often observed during spring at 18- and 25-m than at 40-m depth. Ovigerous females of Gammaropsis ostroumowi and Ampithoe ramondi were observed mainly at 18 and 25m. Juveniles of both species were exclusively recorded at 18 and 25m, so denoting a clear segregation in their population structure with depth. In summary, this study has demonstrated that the ecological pattern of amphipods associated with rhodolith seabeds can vary greatly across both time (seasons) and space (depth).

Diversity of Mosquitoes (Diptera: Culicidae) in the Caatinga Biome, Brazil, from the Widespread to the Endemic

Mosquito fauna in the northeast semiarid region of Brazil, Caatinga biome, are poorly known. Studies on the diversity are scarce and the few surveys available focus on local fauna. In order to understand the ecological pattern of mosquito’s distribution, information available from studies from 2008 to 2015 were gathered. A partitioning framework of the beta diversity, the turnover (βJTU) and nestedness (βJNE) components were used to determine dissimilarity among communities. Eighty-two morphospecies were recorded and 47 of the species were not shared between the areas. The most representative genera were Aedes, Anopheles, Psorophora, Haemagogus, Coquillettidia, and Mansonia, which all include species of medical interest. The communities had high rates of variation, and the mechanism of turnover accounted for the observed diversity pattern. Despite differences in collection methods, the observed dissimilarity may be related to the broad environmental heterogeneity of the biome, the intrinsic relationships of the species with their habitats, and the environmental degradation caused by different types of anthropogenic interference. Considering the mosquito species richness and endemicity, the hypothesis that the Caatinga harbor poor biodiversity is rejected. The spatial variation observed is of particular importance and should be taken into account for the knowledge of Caatinga biodiversity.

SPECIES COMPOSITION AND TERRITORIAL DISTRIBUTION OF BIRDS IN PIEDMONT DAGESTAN

Aim. The paper summarizes the data on bird counts carried out in 1995–2018 in Piedmont Dagestan. Information on the following points was obtained for the first time: composition of bird species, their average abundance, residence status, faunal‐genetic structure, ecological pattern of the avifauna, as well as the features of territorial distribution of birds in Piedmont Dagestan.Methods. Bird counts were carried out on routes without limiting the transect width, with further separate recalculation per area according to the average detection ranges for groups. The faunal‐genetic structure was determined using a standard procedure. The ecological classification is based on the original differentiation of birds according to their occurrence in preferred habitats. The obtained data were processed using cluster, factor and correlation analyses.Results. Of 127 bird species recorded in Piedmont Dagestan, widespread representatives of European, European‐Chinese, Mediterranean, as well as Mongolian fauna predominate, which is associated with the availability of suitable habitats. In the course of cluster analysis, we identified three groups of key areas, reflecting the abundance‐based similarities between bird populations in the studied area. The constructed structural graph illustrates the spatial‐typological organization of the bird population in Piedmont Dagestan. It is established that the development of bird communities in the compared key areas has not only a similar but also distinctive ecological pattern, formed under the influence of such environmental factors as high‐altitude gradient, availability of warmth and water, forest area, rocky outcrops, as well as open areas and man‐made landscapes.Conclusion. The specific ecological pattern of the avifauna in Piedmont Dagestan was developed due to the contribution of both adapted populations of migratory birds of the plains, nesting in the foothills, and to that of the resident communities of typically mountain birds, whose qualitative and quantitative composition changes under the integrated influence of environmental regulatory factors.