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Niche conservatism, the hypothesis that niches remain constant through time and space, is crucial for the study of biological invasions as it underlies native-range based predictions of invasion risk. Niche changes between native and non-native populations are increasingly reported. However, it has been argued that these changes arise mainly because in their novel range, species occupy only a subset of the environments they inhabit in their native range, and not because they expand into environments entirely novel to them. Here, using occurrences of 29 vertebrate species native to either Europe or North America and introduced into the other continent, we assess the prevalence of niche changes between native and non-native populations and assess whether the changes detected are caused primarily by native niche unfilling in the non-native range rather than by expansion into novel environments. We show that niche overlap between native and non-native populations is generally low because of a large degree of niche unfilling in the non-native range. This most probably reflects an ongoing colonization of the novel range, as niche changes were smaller for species that were introduced longer ago and into a larger number of locations. Niche expansion was rare, and for the few species exhibiting larger amounts of niche overlap, an unfilling of the niche in the native range (e.g. through competition or dispersal limitations) is the most probable explanation. The fact that for most species, the realized non-native niche is a subset of the realized native niche allows native-range based niche models to generate accurate predictions of invasion risk. These results suggest that niche changes arising during biological invasions are strongly influenced by propagule pressure and colonization processes, and we argue that introduction history should be taken into account when evaluating niche conservatism in the context of biological invasions.

Sustainable land-use management must account for the potential trade-offs between biodiversity conservation, productive land uses and ecosystem services. In this study, we used Marxan with Zones to generate land use plans that optimize conservation, farming and forestry land uses to reach biodiversity targets while minimizing the opportunity cost for local communities in an inhabited but data-poor National Park in the Andes of Bolivia. Based on six alternative land-use plans, we identified the synergies and trade-offs between the biodiversity benefits achieved in the different plans and the delivery of four locally important water-related ecosystem services modeled with the web-based tool AguAAndes. Although we find synergies between the conservation of high altitude Polylepis woodlands and their associated avifauna and three of the ecosystem services investigated, soil erosion levels were actually higher in scenarios with higher achieved biodiversity benefits. Our study shows how systematic conservation planning and ecosystem service delivery modelling can be used to solve land-use conflicts and identify trade-offs between biodiversity conservation and ecosystem services in a data-poor tropical area.

Invasive alien species are a growing threat to biodiversity, and identifying the mechanisms that enable these species to establish viable populations in their new environment is paramount for management of the problems they pose. Using an unusually large number of both failed and successful documented introductions of parakeets (Aves: Psittacidae) in Europe, we test two of the major hypotheses on the establishment success of invading species, namely the climate-matching and the human-activity hypothesis. European human population centres where ring-necked parakeet (Psittacula krameri) and/or monk parakeet (Myiopsitta monachus) introductions have occurred. Data on ring-necked and monk parakeet introductions in Europe were gathered from various sources, including published books and articles, but also from unpublished reports and local grey literature. Information was verified with experts from the region under consideration. In order to test the climate-matching hypothesis, we verified whether the climatic factors that determine the parakeets' native ranges also explain establishment success in Europe. Parakeet occurrence data from the native ranges were analysed using the presence-only modelling method M axent, and correlations between parakeet establishment and climatic and anthropogenic variables in Europe were assessed using both stepwise logistic regression and the information-theoretic model selection approach. The establishment success of ring-necked and monk parakeets was found to be positively associated with human population density, and, both in the native and in the introduced regions, parakeet occurrence was negatively correlated with the number of frost days. Thus, parakeets are more likely to establish in warmer and human-dominated areas. The large number of independent parakeet introductions in Europe allows us to test the often-used climate-matching and human-activity hypotheses at the species level. We show that both hypotheses offer insight into the invasion process of monk and ring-necked parakeets. Our results suggest that, in the future, parakeet establishment probability may increase even further because global warming is likely to cause a decrease in the number of frost days and because urbanization and human populations are still increasing.

Wildlife diseases are contributing to the current Earth’s sixth mass extinction; one disease, chytridiomycosis, has caused mass amphibian die-offs. While global spread of a hypervirulent lineage of the fungus Batrachochytrium dendrobatidis ( Bd GPL) causes unprecedented loss of vertebrate diversity by decimating amphibian populations, its impact on amphibian communities is highly variable across regions. Here, we combine field data with in vitro and in vivo trials that demonstrate the presence of a markedly diverse variety of low virulence isolates of Bd GPL in northern European amphibian communities. Pre-exposure to some of these low virulence isolates protects against disease following subsequent exposure to highly virulent Bd GPL in midwife toads ( Alytes obstetricans ) and alters infection dynamics of its sister species B. salamandrivorans in newts ( Triturus marmoratus ), but not in salamanders ( Salamandra salamandra ). The key role of pathogen virulence in the complex host-pathogen-environment interaction supports efforts to limit pathogen pollution in a globalized world. The pathogen Batrachochytrium dendrobatidis (BD) associated with widespread amphibian declines is present in Europe but has not consistently caused disease-induced declines in that region. Here, the authors suggest that an endemic strain of BD with low virulence may protect the hosts upon co-infection with more virulent strains.

The chytrid fungal pathogens Batrachochytrium dendrobatidis and Batrachochytrium salamandrivorans cause the skin disease chytridiomycosis in amphibians, which is driving a substantial proportion of an entire vertebrate class to extinction. Mitigation of its impact is largely unsuccessful and requires a thorough understanding of the mechanisms underpinning the disease ecology. By identifying skin factors that mediate key events during the early interaction with B. salamandrivorans zoospores, we discovered a marker for host colonization. Amphibian skin associated beta-galactose mediated fungal chemotaxis and adhesion to the skin and initiated a virulent fungal response. Fungal colonization correlated with the skin glycosylation pattern, with cutaneous galactose content effectively predicting variation in host susceptibility to fungal colonization between amphibian species. Ontogenetic galactose patterns correlated with low level and asymptomatic infections in salamander larvae that were carried over through metamorphosis, resulting in juvenile mortality. Pronounced variation of galactose content within some, but not all species, may promote the selection for more colonization resistant host lineages, opening new avenues for disease mitigation. The skin disease chytridiomycosis is linked to global amphibian declines but effective mitigation measures require improved understanding of the mechanisms underpinning the disease ecology. This study identifies key mediators of interactions between the fungal pathogen and amphibian skin, providing a marker of host colonization that can predict susceptibility between amphibian species.

Invasive species pose a major threat to biodiversity and inflict massive economic costs. Effective management of bio-invasions depends on reliable predictions of areas at risk of invasion, as they allow early invader detection and rapid responses. Yet, considerable uncertainty remains as to how to predict best potential invasive distribution ranges. Using a set of mainly (sub)tropical birds introduced to Europe, we show that the true extent of the geographical area at risk of invasion can accurately be determined by using ecophysiological mechanistic models that quantify species’ fundamental thermal niches. Potential invasive ranges are primarily constrained by functional traits related to body allometry and body temperature, metabolic rates, and feather insulation. Given their capacity to identify tolerable climates outside of contemporary realized species niches, mechanistic predictions are well suited for informing effective policy and management aimed at preventing the escalating impacts of invasive species. Forecasts of risks of invasion by non-native species are challenging to obtain. Here, the authors show that mechanistic models based on functional traits related to species’ capacity to generate and retain body heat identify areas at risk of invasion by non-native birds in Europe.

Quantifying species distributions using species distribution models (SDMs) has emerged as a central method in modern biogeography. These empirical models link species occurrence data with spatial environmental information. Since their emergence in the 1990s, thousands of scientific papers have used SDMs to study organisms across the entire tree of life, with birds commanding considerable attention. Here, we review the current state of avian SDMs and point to challenges and future opportunities for specific applications, ranging from conservation biology, invasive species and predicting seabird distributions, to more general topics such as modeling avian diversity, niche evolution and seasonal distributions at a biogeographic scale. While SDMs have been criticized for being phenomenological in nature, and for their inability to explicitly account for a variety of processes affecting populations, we conclude that they remain a powerful tool to learn about past, current, and future species distributions – at least when their limitations and assumptions are recognized and addressed. We close our review by providing an outlook on prospects and synergies with other disciplines in which avian SDMs can play an important role.

Wildlife trade is a profitable economic activity. Birds are among the most heavily traded animals worldwide, with numerous species threatened by pet trade. Information on both legal and illegal aspects of trade and consumer demand is difficult to obtain across different countries, particularly given substantial socio-economic and cultural variation. Focusing on consumer demand in each country, we conducted a global survey among 105 international experts on bird conservation to identify expected trends, drivers and market characteristics of legal and illegal wild-caught pet bird trade. Our results suggest that future trends in legal bird trade will be mostly driven by socio-cultural motivations and intentional demand for wild-caught, rather than captive-bred birds. Bird popularity and rarity are the main factors expected to influence the choice of which bird species will be the most traded legally. Percentage of rural population was the main national-level socio-economic predictor for legal bird trade in the future. Demand for future illegal trade is expected to be driven by bird popularity and particular species identity. Experts consider illegal trade to be sustained mainly by consumers from higher socio-economic and educational backgrounds. Human population growth rate was the main national-level socio-economic predictor of illegal trade expected for the future. Legislation enforcement remains a critical issue in wildlife trade. Expanding trade networks and socio-economic changes continue to incorporate new regions into the wildlife trade. Investigating the multidimensional and synergistic determinants of wildlife trade will thus help address potential detrimental impacts bird trade might cause on biodiversity.

The fungal skin disease chytridiomycosis threatens global amphibian biodiversity. Among the two causative pathogens, Batrachochytrium dendrobatidis and B . salamandrivorans , the latter has decimated several European salamander populations. However, responses to exposure vary notably across species and individuals, suggesting that understanding the mechanisms behind these variations could enable successful mitigation in surviving populations. A recent study reported that the concentration of epidermal galactose predicts B . salamandrivorans susceptibility at the species level. Here, we used comparative lectin histochemistry with nine lectins to observe lectin staining brightness in the skin and examine its association with the susceptibility of four urodelan species with differential responses to B . salamandrivorans . Subsequently, we exposed Pleurodeles waltl individuals to B . salamandrivorans to assess whether this correlation extends to the individual level. In our study, the degree of labelling with the lectin, Ricinus communis agglutinin I (RCA 1), emerged as the distinctive marker of susceptibility in that resistant species showed minimal RCA 1 binding, while susceptible species exhibited higher levels. Results of the infection trial further demonstrated that an increase in staining brightness correlates with steeper infection slopes at initial stages of infection. This demonstrates RCA 1-binding glycans as a biomarker for individual susceptibility and presents the basis for marker-assisted selection in P. waltl .

Background More and more forest management focuses on increasing structural complexity to improve environmental conditions for biodiversity and forest functioning. However, it remains uncertain whether animal populations also benefit from increased forest structure. Small mammals are key reservoirs for zoonotic diseases, so understanding how forest structure changes their condition and how this, in turn, affects infection dynamics is critical for animal and human health. Methods This study examined relationships between forest structural complexity, individual body condition (scaled mass index (SMI) and telomere length), pathogen prevalence, and tick load in bank voles and wood mice across 19 forest plots in northern Belgium, representing a gradient of structural complexity. Results Results showed that higher forest complexity, especially with more dead wood and a well-developed herb layer, increased small mammal abundance. Density varied by tree species, with highest abundances in oak and lowest in poplar forests. In addition, body condition improved with structural complexity; SMI increased with woody layer complexity in wood mice and with dead wood availability in bank voles. No clear relationship between telomere length and forest complexity was observed. The relationship between body condition and pathogen prevalence was species- and pathogen-specific. Small mammals in better body condition were more likely to host Borrelia burgdorferi (causing Lyme disease), particularly in complex forests, indicating a higher infection risk with increasing structural complexity. Conclusions Forest management practices that aim to enhance forest structure and biodiversity may thus inadvertently increase zoonotic disease risk and should take these findings in consideration to minimize the risk for human health. Graphical abstract