The global loss of floristic uniqueness

Regional species assemblages have been shaped by colonization, speciation and extinction over millions of years. Humans have altered biogeography by introducing species to new ranges. However, an analysis of how strongly naturalized plant species (i.e. alien plants that have established self-sustaining populations) affect the taxonomic and phylogenetic uniqueness of regional floras globally is still missing. Here, we present such an analysis with data from native and naturalized alien floras in 658 regions around the world. We find strong taxonomic and phylogenetic floristic homogenization overall, and that the natural decline in floristic similarity with increasing geographic distance is weakened by naturalized species. Floristic homogenization increases with climatic similarity, which emphasizes the importance of climate matching in plant naturalization. Moreover, floristic homogenization is greater between regions with current or past administrative relationships, indicating that being part of the same country as well as historical colonial ties facilitate floristic exchange, most likely due to more intensive trade and transport between such regions. Our findings show that naturalization of alien plants threatens taxonomic and phylogenetic uniqueness of regional floras globally. Unless more effective biosecurity measures are implemented, it is likely that with ongoing globalization, even the most distant regions will lose their floristic uniqueness.

Distance to native climatic niche margins explains establishment success of alien mammals

One key hypothesis explaining the fate of exotic species introductions posits that the establishment of a self-sustaining population in the invaded range can only succeed within conditions matching the native climatic niche. Yet, this hypothesis remains untested for individual release events. Using a dataset of 979 introductions of 173 mammal species worldwide, we show that climate-matching to the realized native climatic niche, measured by a new Niche Margin Index (NMI), is a stronger predictor of establishment success than most previously tested life-history attributes and historical factors. Contrary to traditional climatic suitability metrics derived from species distribution models, NMI is based on niche margins and provides a measure of how distant a site is inside or, importantly, outside the niche. Besides many applications in research in ecology and evolution, NMI as a measure of native climatic niche-matching in risk assessments could improve efforts to prevent invasions and avoid costly eradications.

Senecio pseudoarnica Less. (Asteraceae) – a new non-native species invading coastal areas in arctic and subarctic Europe

We report the human-assisted spread of Senecio pseudoarnica, native to the northern coasts of North America and the Far East, to arctic and subarctic regions of Europe. Our findings indicate that the species, imported as a decorative plant, is currently rapidly spreading along coastal areas of Iceland and Norway. An exponential model comprehensively explained the increase in the number of known localities. Close climate matching between the native and non-native ranges (shown by our preliminary analyses), as well as practically exact environmental matching, are the main factors that facilitate the process of naturalisation and invasion. S. pesudoarnica is one of the very few species invading these arctic and subarctic regions.

Seed Sourcing Strategies Considering Climate Change Forecasts: A Practical Test in Scots Pine

Research Highlights: We experimentally tested different seed sourcing strategies (local, predictive, climate-predictive, climate-adjusted, composite and admixture) under a climate change high emissions scenario using a Scots pine multi-site provenance test. Background and Objectives: There is an urgent need to conserve genetic resources and to support resilience of conifer species facing expected changes and threats. Seed sourcing strategies have been proposed to maximize the future adaptation and resilience of our forests. However, these proposals are yet to be tested, especially in long-lived organisms as forest trees, due to methodological constraints. In addition, some methods rely on the transfer of material from populations matching the future conditions of the sites. However, at the rear edge of the species, some specific problems (high fragmentation, high genetic differentiation, role of genetic drift) challenge the theoretical expectations of some of these methods. Materials and Methods: We used a Scots pine multi-site provenance test, consisting of seventeen provenances covering the distribution range of the species in Spain tested in five representative sites. We measured height, diameter and survival at 5, 10 and 15 years after planting. We simulated populations of 50 trees by bootstrapping material of the provenance test after removing the intra-site environmental effects, simulating different seed sourcing strategies. Results: We found that local and predictive methods behaved better than methods based on the selection of future climate-matching strategies (predictive-climate and climate-adjusted) and those combining several seed sources (composite and admixture seed sourcing strategies). Conclusions: Despite the theoretical expectations, for Scots pine, a forest tree species at its rear edge of its distribution, seed-sourcing methods based on climate matching or a combination of seed sources do not perform better than traditional local or predictive methods or they are not feasible because of the lack of future climate-matching populations.

Conservation paradox of giant arapaima Arapaima gigas (Schinz, 1822) (Pisces: Arapaimidae): endangered in its native range in Brazil and invasive in Indonesia

Ornamental aquaculture is known to be one of the main sources of non-native species and Indonesia has been identified as one of the leading suppliers of these organisms worldwide. Released or escaped ornamental aquatic animals can establish new populations and become invasive. On the other hand, some invasive species can be also endangered in their native range, which is called the “Biodiversity Conservation Paradox”. This is true for Arapaima gigas, one of the popular ornamental creatures and the largest bony fish of all, which is threatened in its native range in parts of Amazonia and which has been found to occur in various localities in Java and Sumatra in Indonesia. Based on climate matching we found the vast majority of Indonesian territory to be suitable for this species establishment. Keeping in mind the size and predatory behaviour of A. gigas, we discussed possible consequences of its spread and impacts on native biota in Indonesia.

Two species of illegal South American sailfin catfish of the genus Pterygoplichthys well-established in Indonesia

Sailfin catfish indigenous to South America are very popular ornamental fish, having previously been introduced to many regions outside their native range. Two species, namely Pterygoplichthys disjunctivus and P. pardalis, are illegal but widespread in Indonesia. They have formed self-sustaining populations, exploited for feeding of domestic animals and locally for human consumption. Also possible hybrids of the two mentioned species were recorded. The surveyed populations were considered established which perfectly fits with the climate matching analysis. Further monitoring and inspection of regions highlighted to be suitable for sailfin catfish is recommended.

Invasive Potential of Pet-Traded Pill-Box Crabs from Genus Limnopilos

The pet trade in aquatic animals is known to be one of the main sources of non-native species worldwide. Freshwater decapod crustaceans have increased in popularity as ornamentals in the last two decades. Freshwater crabs of the genus Limnopilos were discovered by hobby aquarists and introduced on the market in 2008. They are generally considered interesting additions to an aquarium, but information about their living requirements are scarce. Additionally, their invasive potential is not known. Here, we present a survey of the availability of Limnopilos crabs on the market in Europe and North America and analyzed the invasive potential of all species from the genus based on climate matching from a global perspective. The only species recorded in the pet trade is L. naiyanetri, but future introduction of other species is discussed. Certain tropical regions were identified as the most suitable for the potential establishment of Limnopilos crabs including the northern part of South America, and L. microrhynchus was evaluated as the highest risk species. In this pilot study, we also suggest some points to be answered regarding further improving the risk assessment and also recommend continuous monitoring of the market for ornamental decapods.