En route to the North: modelling crested porcupine habitat suitability and dispersal flows across a highly anthropized area in northern Italy

The crested porcupine (Hystrix cristata) underwent a rapid and widespread range expansion in Italy. Nowadays the species is moving towards the northernmost regions of the country and its occurrence is increasing in the highly anthropized Po Plain. Our objectives were to evaluate the suitability of the Po Plain for the species, as well as to identify dispersal corridors connecting the northern Apennines occurrence areas and the Prealps. We modelled the species home-range scale habitat suitability based on an ensemble modelling approach. Additionally, a habitat suitability prediction carried out at a finer scale was used to parametrize the landscape resistance, based on which we modelled the potential dispersal corridors for the species using a factorial least-cost path approach. The ensemble prediction estimated a potential occurrence of the crested porcupine in 27.4% of the study area. The species occurrence probability was mainly driven by the distribution of extensive cultivations, woodlands and shrublands, and water courses and by the annual mean temperature. Conversely, the movements of the species resulted mainly sustained by woodlands and shrublands and highly hindered by simple arable lands and rice paddies. The connectivity prediction showed that three main dispersal routes are likely to connect crested porcupine occurrence areas in the northern Apennines to currently unoccupied but highly suitable areas in the Prealps. The study allowed us to identify the areas in the Prealps with the highest probability to be colonized by the crested porcupine in the near future and provided important insights for the conservation of a strictly protected species in a human-dominated landscape.

Multilocus phylogeny and historical biogeography of Hypostomus shed light on the processes of fish diversification in La Plata Basin

Distribution history of the widespread Neotropical genus Hypostomus was studied to shed light on the processes that shaped species diversity. We inferred a calibrated phylogeny, ancestral habitat preference, ancestral areas distribution, and the history of dispersal and vicariance events of this genus. The phylogenetic and distribution analyses indicate that Hypostomus species inhabiting La Plata Basin do not form a monophyletic clade, suggesting that several unrelated ancestral species colonized this basin in the Miocene. Dispersal to other rivers of La Plata Basin started about 8 Mya, followed by habitat shifts and an increased rate of cladogenesis. Amazonian Hypostomus species colonized La Plata Basin several times in the Middle Miocene, probably via the Upper Paraná and the Paraguay rivers that acted as dispersal corridors. During the Miocene, La Plata Basin experienced marine incursions, and geomorphological and climatic changes that reconfigured its drainage pattern, driving dispersal and diversification of Hypostomus. The Miocene marine incursion was a strong barrier and its retraction triggered Hypostomus dispersal, increased speciation rate and ecological diversification. The timing of hydrogeological changes in La Plata Basin coincides well with Hypostomus cladogenetic events, indicating that the history of this basin has acted on the diversification of its biota.

Predicting terrestrial dispersal corridors of the invasive African clawed frog Xenopus laevis in Portugal

Invasive species, such as the mainly aquatic African clawed frog Xenopus laevis, are a main threat to global biodiversity. The identification of dispersal corridors is necessary to restrict further expansion of these species and help to elaborate management plans for their control and eradication. Here we use remote sensing derived resistance surfaces, based on the normalised difference vegetation index (NDVI) and the normalised difference water index (NDWI) accounting for behavioural and physiological dispersal limitations of the species, in combination with elevation layers, to determine fine scale dispersal patterns of invasive populations of X. laevis in Portugal, where the frog had established populations in two rivers. We reconstruct past dispersal routes between these two invaded rivers and highlight high risk areas for future expansion. Our models suggest terrestrial dispersal corridors that connect both invaded rivers and identify artificial water bodies as stepping stones for overland movement of X. laevis. Additionally, we found several potential stepping stones into novel areas and provide concrete information for invasive species management.

Environmental variables affect the diversity of adult damselflies (Odonata: Zygoptera) in western Amazonia

Our study evaluated the effects of environmental variables on the assemblages of the suborder Zygoptera, and tested the hypothesis that environmental variables are more important determinants of the structure of these assemblages than limnological variables in streams. We sampled 17 streams in the Carajás National Forest and tested our hypothesis using a linear regression analysis, with the zygopteran species composition, richness, and abundance as the response variables. Our findings indicate that both limnological and physical variables influence, independently, the characteristics of the zygopteran assemblages. The riparian forest maintains the stability of the environment and provides dispersal corridors, along which the zygopterans can reach alternative, suitable environments. The small scale of this study also implies that the continuity of the vegetation is essential for the dispersal of the zygopterans among different landscapes. The high levels of abundance recorded in the better-preserved environments may reflect the maintenance of specific habitats and resource availability. Riparian forest is crucial to the ecological equilibrium of the stream systems, although further research at a broader spatial scale that focuses on a greater diversity of variables should provide more robust insights into the phenomenon.

Felids, forest and farmland: identifying high priority conservation areas in Sumatra

Context Effective planning for protected areas and wildlife population management requires a firm understanding of the location of the species’ core habitat patches, the dispersal corridors connecting them, and the risk they face from key threats, notably deforestation. Objectives To quantify and map core habitat patches and dispersal corridors for Sunda clouded leopard (Neofelis diardi diardi), Asiatic golden cat (Catopuma temminckii) and marbled cat (Pardofelis marmorata) across the 16,000 km2 tropical rainforest Kerinci Seblat landscape, Sumatra. Also, to model future forest loss and fragmentation and its effect on landscape connectivity for populations of these threatened species. Methods Using data from camera trap (671 sites/55,856 trap nights), and occupancy modelling, we developed habitat use maps and converted these into species-specific landscape resistance layers. We applied cumulative resistant kernels to map core areas and we used factorial least-cost paths to define dispersal corridors. A 17-year deforestation dataset was used to predict deforestation risk towards the integrity of corridors and core areas. Results The occupancy estimates of the three cats were similar (0.18–0.29), with preference shown for habitats with dense tree cover, medium elevation and low human disturbance. The overlap between core areas and corridors across the three species was moderate, 7–11% and 10%, respectively. We predicted future loss of 1052 km2 of forest in the landscape, of which 2–4% and 5% in highly importance core areas and corridors. Conclusions This study provides a valuable guidance for identifying priority areas in need of urgent protection within and outside the protected area network, and where infrastructure development planning can incorporate wildlife conservation goals.

Clustering of dispersal corridors in metapopulations leads to higher rates of recovery following subpopulation extinction

Understanding how spatially divided populations are affected by the physical characteristics of the landscapes they occupy is critical to their conservation. While some metapopulations have dispersal corridors spread relatively evenly through space in a homogeneous arrangement such that most subpopulations are connected to a few neighbors, others may have corridors clustered in a heterogeneous arrangement, creating a few highly connected subpopulations and leaving most subpopulations with only one or two neighbors. Graph theory and empirical data from other biological and non-biological networks suggest that heterogeneous metapopulations should be the most robust to subpopulation extinction. Here, I used Pseudomonas syringae pv. syringae B728a in metapopulation microcosms to compare the recovery of metapopulations with homogeneous and heterogeneous corridor arrangements following small, medium, and large subpopulation extinction events. I found that while metapopulations with heterogeneous corridor arrangements had the fastest rates of recovery following extinction events of all sizes and had the shortest absolute time to recovery following medium-sized extinction events, metapopulations with homogeneous corridor arrangements had the shortest time to recovery following the smallest extinction events.

Integrating Phylogeographic Analysis and Geospatial Methods to Infer Historical Dispersal Routes and Glacial Refugia of Liriodendron chinense

Liriodendron chinense (Hemsl.), a Tertiary relic tree, is mainly distributed in subtropical China. The causes of the geographical distribution pattern of this species are poorly understood. In this study, we inferred historical dispersal routes and glacial refugia of this species by combining genetic data (chloroplast DNA (cpDNA), nuclear ribosomal DNA (nrDNA), and nuclear DNA (nDNA)) and geospatial data (climate and geology) with the methods of landscape genetics. Additionally, based on sequence variation at multiple loci, we employed GenGIS and Barrier software to analyze L. chinense population genetic structure. Dispersal corridors and historical gene flow between the eastern and western populations were detected, and they were located in mountainous regions. Based on species distribution model (SDMs), the distribution patterns in paleoclimatic periods were consistent with the current pattern, suggesting the presence of multiple refuges in multiple mountainous regions in China. The genetic structure analysis clustered most eastern populations into a clade separated from the western populations. Additionally, a genetic barrier was detected between the eastern and western populations. The dispersal corridors and historical gene flow detected here suggested that the mountains acted as a bridge, facilitating gene flow between the eastern and western populations. Due to Quaternary climatic fluctuations, the habitats and dispersal corridors were frequently inhabited by warm-temperate evergreen forests, which may have fragmented L. chinense habitats and exacerbated the differentiation of eastern and western populations. Ultimately, populations retreated to multiple isolated mountainous refugia, shaping the current geographical distribution pattern. These dispersal corridors and montane refugia suggested that the mountains in subtropical China play a crucial role in the conservation of genetic resources and migration of subspecies or related species in this region.