Population and distribution of beavers Castor fiber

1. A century ago, overhunting had reduced Eurasian beaver Castor fiber populations to c. 1200 animals in scattered refugia from France to Mongolia. Reintroductions and natural spread have since restored the species to large areas of its original range. Population has more than tripled since the first modern estimate in 1998; the minimum estimate is now c. 1.5 million. 2. Range expansion 2000–2020 has been rapid, with large extensions in western and south-central Europe, southern Russia, and west and central Siberia. Beavers are now re-established in all countries of their former European range except for Portugal, Italy, and the southern Balkans; they occur broadly across Siberia to Mongolia, with scattered populations father east. About half of the world population lives in Russia. Populations appear to be mature in much of European Russia, Belarus, the Baltic States, and Poland. 3. There is a significant population of North American beaver Castor canadensis in Finland and north-west Russia. Most other 20th-Century introductions of this species have become extinct or been removed. 4. Recent DNA studies have improved understanding of Castor fiber population prehistory and history. Two clades, east and west, are extant; a third ‘Danube’ clade is extinct. Refugial populations were strongly bottlenecked, with loss of genetic diversity through genetic drift. 5. Future range extension, and large increases in populations and in impacts on freshwater systems, can be expected. Beavers are now recolonising densely populated, intensely modified, low-relief regions, such as England, the Netherlands, Belgium, and north-west Germany. They will become much more common and widespread there in coming decades. As beavers are ecosystem engineers with profound effects on riparian habitats, attention to integrating beaver management into these landscapes using experience gained in other areas – before the rapid increase in population densities and impacts occurs – is recommended. beaver, Castor fiber, Castor canadensis, distribution, Eurasia, population, reintroductionpublishedVersio

Next‐generation phylogeography resolves post‐glacial colonization patterns in a widespread carnivore, the red fox (Vulpes vulpes), in Europe

Carnivores tend to exhibit a lack of (or less pronounced) genetic structure at continental scales in both a geographic and temporal sense and this can confound the identification of post-glacial colonization patterns in this group. In this study we used genome-wide data (using genotyping by sequencing [GBS]) to reconstruct the phylogeographic history of a widespread carnivore, the red fox (Vulpes vulpes), by investigating broad-scale patterns of genomic variation, differentiation and admixture amongst contemporary populations in Europe. Using 15,003 single nucleotide polymorphisms (SNPs) from 524 individuals allowed us to identify the importance of refugial regions for the red fox in terms of endemism (e.g., Iberia). In addition, we tested multiple post-glacial recolonization scenarios of previously glaciated regions during the Last Glacial Maximum using an Approximate Bayesian Computation (ABC) approach that were unresolved from previous studies. This allowed us to identify the role of admixture from multiple source population post-Younger Dryas in the case of Scandinavia and ancient land-bridges in the colonization of the British Isles. A natural colonization of Ireland was deemed more likely than an ancient human-mediated introduction as has previously been proposed and potentially points to a larger mammalian community on the island in the early post-glacial period. Using genome-wide data has allowed us to tease apart broad-scale patterns of structure and diversity in a widespread carnivore in Europe that was not evident from using more limited marker sets and provides a foundation for next-generation phylogeographic studies in other non-model species