Spatial correlations in geographical spreading of COVID-19 in the United States

The global spread of the COVID-19 pandemic has followed complex pathways, largely attributed to the high virus infectivity, human travel patterns, and the implementation of multiple mitigation measures. The resulting geographic patterns describe the evolution of the epidemic and can indicate areas that are at risk of an outbreak. Here, we analyze the spatial correlations of new active cases in the USA at the county level and characterize the extent of these correlations at different times. We show that the epidemic did not progress uniformly and we identify various stages which are distinguished by significant differences in the correlation length. Our results indicate that the correlation length may be large even during periods when the number of cases declines. We find that correlations between urban centers were much more significant than between rural areas and this finding indicates that long-range spreading was mainly facilitated by travel between cities, especially at the first months of the epidemic. We also show the existence of a percolation transition in November 2020, when the largest part of the country was connected to a spanning cluster, and a smaller-scale transition in January 2021, with both times corresponding to the peak of the epidemic in the country.

Idea Paper: improving forecasts of community composition with lightweight biodiversity monitoring across ecological and anthropogenic disturbance gradients

Accurate and up-to-date biodiversity forecasts enable robust planning for environmental management and conservation of landscapes under a wide range of uses. Future predictions of the species composition of ecological communities complement more frequently reported species richness estimates to better characterize the different dimensions of biodiversity. The models that make community composition forecasts are calibrated with data on species’ geographic patterns for the present, which may not be good proxies for future patterns. The future establishment of novel communities represents data on species interactions unaccounted for by these models. However, detecting them in a systematic way presents challenges due to the lack of monitoring data for landscapes with high environmental turnover, where such communities are likely to establish. Here, we propose lightweight monitoring over both ecological and anthropogenic disturbance gradients using passive sensors (i.e., those that operate continuously without much human input) to detect novel communities with the aim of updating models that make community composition forecasts. Monitoring over these two gradients should maximize detection of novel communities and improve understanding of relationships between community composition and environmental change. Further, barriers regarding cost and effort are reduced by using relatively few sensors requiring minimal upkeep. Ongoing updates to community composition forecasts based on novel community data and better understanding of the associated uncertainty should improve future decision-making for both resource management and conservation efforts.

Geographic patterns of koala retrovirus genetic diversity, endogenization and subtype distributions

Koala retrovirus subtype A is the youngest endogenized retrovirus, providing a unique system to elucidate retroviral-host co-evolution. We characterised KoRV geography using faecal DNA from 192 samples across 20 populations throughout the koala’s range. We reveal an abrupt change in KoRV genetics and incidence at the Victoria/NSW state border. In northern koalas, pol gene copies were ubiquitously present at greater than 5 per-cell, consistent with endogenous KoRV. In southern koalas, pol copies were detected in only 25.8% of koalas and always at copy numbers less than one, while the env gene was detected in all animals and in a majority at copy numbers of greater than one per-cell. These results suggest that southern koalas carry partial endogenous KoRV-like sequences. Deep sequencing of the env hypervariable region revealed three putatively endogenous KoRV-A sequences in northern koalas and a single, distinct sequence present in all southern koalas. Among northern populations, env sequence diversity decreased with distance from the equator, suggesting infectious KoRV-A invaded the koala genome in northern Australia and then spread south. The previously described exogenous KoRV subtypes (B-K), two novel subtypes (L and M), and intermediate or hybrid subtypes were detected in all northern koala populations but strikingly absent from all southern animals tested. Apart from KoRV-D, these exogenous subtypes were generally locally prevalent but geographically restricted, producing KoRV genetic differentiation among northern populations. This suggests that sporadic evolution and local transmission of the exogenous subtypes has occurred within northern Australia, but this has not extended into animals within southern Australia.

Population genetics and connectivity in Paphies subtriangulata and Paphies australis (Bivalvia: Mesodesmatidae)

<p>Understanding the different types of genetic population structure that characterise marine species, and the processes driving such patterns, is crucial for establishing links between the ecology and evolution of a species. This knowledge is vital for management and conservation of marine species. Genetic approaches are a powerful tool for revealing ecologically relevant insights to marine population dynamics. Geographic patterns of genetic population structure are largely determined by the rate at which individuals are exchanged among populations (termed ‘population connectivity’), which in turn is influenced by conditions in the physical environment. The complexity of the New Zealand marine environment makes it difficult to predict how physical oceanographic and environmental processes will influence connectivity in coastal marine organisms and hence the type of genetic structure that will form. This complexity presents a challenge for management of marine resources but also makes the New Zealand region an interesting model system to investigate how and why population structure develops and evolves over time. Paphies subtriangulata (tuatua) and P. australis (pipi) are endemic bivalve ‘surf clams’ commonly found on New Zealand surf beaches and harbour/estuary environments, respectively. They form important recreational, customary and commercial fisheries, yet little is known about the stock structure of these species. This study aimed to use genetic techniques to determine population structure, levels of connectivity and ‘seascape’ genetic patterns in P. subtriangulata and P. australis, and to gain further knowledge of common population genetic processes operating in the New Zealand coastal marine environment. Eleven and 14 novel microsatellite markers were developed for P. subtriangulata and P. australis, respectively. Samples were collected from 10 locations for P. subtriangulata and 13 locations for P. australis (35-57 samples per location; total sample size of 517 for P. subtriangulata and 674 for P. australis). Geographic patterns of genetic variation were measured and rates of migration among locations were estimated on recent and historic time scales. Both species were characterised by genetic population structure that was consistent with their habitat. For P. subtriangulata, the Chatham Island population was strongly differentiated from the rest of the sampled locations. The majority of mainland locations were undifferentiated and estimated rates of migration among locations were high on both time scales investigated, although differentiation among some populations was observed. For P. australis, an overall isolation by distance (IBD) pattern was likely to be driven by distance between discrete estuary habitats. However, it was difficult to distinguish IBD from hierarchical structure as populations could be further subdivided into three significantly differentiated groups (Northern, South Eastern and South Western), providing evidence for barriers to dispersal. Further small scale patterns of genetic differentiation were observed in some locations, suggesting that complex current patterns and high self-recruitment drive small scale genetic population structure in both P. subtriangulata and P. australis. These patterns of genetic variation were used in seascape genetic analyses to test for associations with environmental variables, with the purpose of understanding the processes that might shape genetic population structure in these two species. Although genetic population structure varied between the two species, common physical and environmental variables (geographic distance, sea surface temperature, bed slope, tidal currents) are likely to be involved in the structuring of populations. Results suggest that local adaptation, in combination with restricted dispersal, could play a role in driving the small scale patterns of genetic differentiation seen among some localities. Overall, the outcomes of this research fill a gap in our knowledge about the rates and routes by which populations are connected and the environmental factors influencing such patterns in the New Zealand marine environment. Other studies have highlighted the importance of using multi-faceted approaches to understand complex processes operating in the marine environment. The present study is an important first step in this direction as these methods are yet to be widely applied to New Zealand marine species. Importantly, this study used a comparative approach, applying standardised methodology to compare genetic population structure and migration across species. Such an approach is necessary if we wish to build a robust understanding of the spatial and temporal complexities of population dynamics in the New Zealand coastal marine environment, and to develop effective management strategies for our unique marine species.</p>

Population genetics and connectivity in Paphies subtriangulata and Paphies australis (Bivalvia: Mesodesmatidae)

<p>Understanding the different types of genetic population structure that characterise marine species, and the processes driving such patterns, is crucial for establishing links between the ecology and evolution of a species. This knowledge is vital for management and conservation of marine species. Genetic approaches are a powerful tool for revealing ecologically relevant insights to marine population dynamics. Geographic patterns of genetic population structure are largely determined by the rate at which individuals are exchanged among populations (termed ‘population connectivity’), which in turn is influenced by conditions in the physical environment. The complexity of the New Zealand marine environment makes it difficult to predict how physical oceanographic and environmental processes will influence connectivity in coastal marine organisms and hence the type of genetic structure that will form. This complexity presents a challenge for management of marine resources but also makes the New Zealand region an interesting model system to investigate how and why population structure develops and evolves over time. Paphies subtriangulata (tuatua) and P. australis (pipi) are endemic bivalve ‘surf clams’ commonly found on New Zealand surf beaches and harbour/estuary environments, respectively. They form important recreational, customary and commercial fisheries, yet little is known about the stock structure of these species. This study aimed to use genetic techniques to determine population structure, levels of connectivity and ‘seascape’ genetic patterns in P. subtriangulata and P. australis, and to gain further knowledge of common population genetic processes operating in the New Zealand coastal marine environment. Eleven and 14 novel microsatellite markers were developed for P. subtriangulata and P. australis, respectively. Samples were collected from 10 locations for P. subtriangulata and 13 locations for P. australis (35-57 samples per location; total sample size of 517 for P. subtriangulata and 674 for P. australis). Geographic patterns of genetic variation were measured and rates of migration among locations were estimated on recent and historic time scales. Both species were characterised by genetic population structure that was consistent with their habitat. For P. subtriangulata, the Chatham Island population was strongly differentiated from the rest of the sampled locations. The majority of mainland locations were undifferentiated and estimated rates of migration among locations were high on both time scales investigated, although differentiation among some populations was observed. For P. australis, an overall isolation by distance (IBD) pattern was likely to be driven by distance between discrete estuary habitats. However, it was difficult to distinguish IBD from hierarchical structure as populations could be further subdivided into three significantly differentiated groups (Northern, South Eastern and South Western), providing evidence for barriers to dispersal. Further small scale patterns of genetic differentiation were observed in some locations, suggesting that complex current patterns and high self-recruitment drive small scale genetic population structure in both P. subtriangulata and P. australis. These patterns of genetic variation were used in seascape genetic analyses to test for associations with environmental variables, with the purpose of understanding the processes that might shape genetic population structure in these two species. Although genetic population structure varied between the two species, common physical and environmental variables (geographic distance, sea surface temperature, bed slope, tidal currents) are likely to be involved in the structuring of populations. Results suggest that local adaptation, in combination with restricted dispersal, could play a role in driving the small scale patterns of genetic differentiation seen among some localities. Overall, the outcomes of this research fill a gap in our knowledge about the rates and routes by which populations are connected and the environmental factors influencing such patterns in the New Zealand marine environment. Other studies have highlighted the importance of using multi-faceted approaches to understand complex processes operating in the marine environment. The present study is an important first step in this direction as these methods are yet to be widely applied to New Zealand marine species. Importantly, this study used a comparative approach, applying standardised methodology to compare genetic population structure and migration across species. Such an approach is necessary if we wish to build a robust understanding of the spatial and temporal complexities of population dynamics in the New Zealand coastal marine environment, and to develop effective management strategies for our unique marine species.</p>

Nitrogen use efficiency of terrestrial plants in China: geographic patterns, evolution, and determinants

Background Plant nitrogen use efficiency (NUE) is an important ecological indicator that reflects the capacity of a plant to transform nitrogen into production, which is essential for further elucidating plant growth and terrestrial ecosystem productivity. Although there are a growing number of studies that address NUE changes at local scales, the variations of NUE over large spatial scales remain unclear. In this study, we analyzed the geographic patterns of NUE and explored its phylogenic and environmental drivers across 1452 species at 1102 sites in China. Results NUE tended to decrease with latitude (r = − 0.56), whereas it increased with longitude (r = 0.54), and varied widely in different ecosystems and plant life forms. Furthermore, NUE was negatively correlated with plant foliar phosphorus concentration (r = − 0.53), soil pH (r = − 0.10), soil total phosphorus (r = − 0.13) and available phosphorus (r = − 0.05), but positively with the mean annual temperature (r = 0.32), annual precipitation (r = 0.27), and aridity index (r = 0.26). NUE was significantly altered with phylogeny and evolved toward a lower value (r = − 0.28), which may have been due to increasing nitrogen deposition and fixation in biogeochemical evolution. Overall, the combination of foliar phosphorus concentration, phylogeny, climate, and soil properties accounted for 52.7% of the total variations of NUE. In particular, foliar phosphorus concentration was the most important factor, whereas plant evolutionary history was second in contributing to NUE variations. Conclusions Our study emphasizes the pivotal role of plant stoichiometry and phylogeny in nitrogen cycling and suggests incorporating them into earth system models to better understanding plant growth and nitrogen cycling in the context of environmental changes.

Environmental Drivers of Diversification and Hybridization in Neotropical Butterflies

Studying how the environment shapes current biodiversity patterns in species rich regions is a fundamental issue in biogeography, ecology, and conservation. However, in the Neotropics, the study of the forces driving species distribution and richness, is mostly based on vertebrates and plants. In this study, we used 54,392 georeferenced records for 46 species and 1,012 georeferenced records for 38 interspecific hybrids of the Neotropical Heliconius butterflies to investigate the role of the environment in shaping their distribution and richness, as well as their geographic patterns of phylogenetic diversity and phylogenetic endemism. We also evaluated whether niche similarity promotes hybridization in Heliconius. We found that these insects display five general distribution patterns mostly explained by precipitation and isothermality, and to a lesser extent, by altitude. Interestingly, altitude plays a major role as a predictor of species richness and phylogenetic diversity, while precipitation explains patterns of phylogenetic endemism. We did not find evidence supporting the role of the environment in facilitating hybridization because hybridizing species do not necessarily share the same climatic niche despite some of them having largely overlapping geographic distributions. Overall, we confirmed that, as in other organisms, high annual temperature, a constant supply of water, and spatio-topographic complexity are the main predictors of diversity in Heliconius. However, future studies at large scale need to investigate the effect of microclimate variables and ecological interactions.

Using MapMCDA Tool for the Spatial Epidemiology of Animal Rabies in Morocco: How to Improve the Rationality of a Qualitative Risk Assessment

Objective The objective behind this article is to better characterize spatial distribution of animal rabies in Morocco through qualitative risk assessment framework. In Morocco, the occurrence of the disease is neither clearly distributed nor complete. Therefore, risk assessment methods become strongly recommended to cope with distorted geographic patterns. Methods Based on data collection set from 168 counties, qualitative changes on spatial epidemiology of rabies were analysed by mapMCDA tool covering a period from 2004 to 2017 and including information on determinants of the geographic distribution of animal rabies in Morocco defined in previous work. Results To validate the risk assessment model, the results were compared to rabies cases reported during the study period. The clustering of the rabies risk estimates is decisive and highly reliable. A significant alignment was shown between the very high and high-risk estimates. Conclusion This study is the first attempt that has been made for using MapMCDA for rabies. For a normative process aiming to avoid subjectivity related to expert-opinions, authors suggest conducting initially a statistical multiple component analysis that will provide quantified estimates of risk factors. It would be an advisable decision-making tool that helps to design oriented surveillance and allows better referral of actions to control the disease.