Evidence of rapid change in genetic structure and diversity during range expansion in a recovering large terrestrial carnivore

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Admixture and gene flow from Russia in the recovering Northern European brown bear (Ursus arctos)

Large carnivores were persecuted to near extinction during the last centuries, but have now recovered in some countries. It has been proposed earlier that the recovery of the Northern European brown bear is supported by migration from Russia. We tested this hypothesis by obtaining for the first time continuous sampling of the whole Finnish bear population, which is located centrally between the Russian and Scandinavian bear populations. The Finnish population is assumed to experience high gene flow from Russian Karelia. If so, no or a low degree of genetic differentiation between Finnish and Russian bears could be expected. We have genotyped bears extensively from all over Finland using 12 validated microsatellite markers and compared their genetic composition to bears from Russian Karelia, Sweden, and Norway. Our fine masked investigation identified two overlapping genetic clusters structured by isolation-by-distance in Finland (pairwise FST = 0.025). One cluster included Russian bears, and migration analyses showed a high number of migrants from Russia into Finland, providing evidence of eastern gene flow as an important driver during recovery. In comparison, both clusters excluded bears from Sweden and Norway, and we found no migrants from Finland in either country, indicating that eastern gene flow was probably not important for the population recovery in Scandinavia. Our analyses on different spatial scales suggest

Brown bear attacks on humans : a worldwide perspective

The increasing trend of large carnivore attacks on humans not only raises human safety concerns but may also undermine large carnivore conservation efforts. Although rare, attacks by brown bears Ursus arctos are also on the rise and, although several studies have addressed this issue at local scales, information is lacking on a worldwide scale. Here, we investigated brown bear attacks (n = 664) on humans between 2000 and 2015 across most of the range inhabited by the species: North America (n = 183), Europe (n = 291), and East (n = 190). When the attacks occurred, half of the people were engaged in leisure activities and the main scenario was an encounter with a female with cubs. Attacks have increased significantly over time and were more frequent at high bear and low human population densities. There was no significant difference in the number of attacks between continents or between countries with different hunting practices. Understanding global patterns of bear attacks can help reduce dangerous encounters and, consequently, is crucial for informing wildlife managers and the public about appropriate measures to reduce this kind of conflicts in bear country.Peer reviewe

Abrasive, Silica Phytoliths and the Evolution of Thick Molar Enamel in Primates, with Implications for the Diet of Paranthropus boisei

Background: Primates—including fossil species of apes and hominins—show variation in their degree of molar enamel thickness, a trait long thought to reflect a diet of hard or tough foods. The early hominins demonstrated molar enamel thickness of moderate to extreme degrees, which suggested to most researchers that they ate hard foods obtained on or near the ground, such as nuts, seeds, tubers, and roots. We propose an alternative hypothesis—that the amount of phytoliths in foods correlates with the evolution of thick molar enamel in primates, although this effect is constrained by a species ’ degree of folivory. Methodology/Principal Findings: From a combination of dietary data and evidence for the levels of phytoliths in plant families in the literature, we calculated the percentage of plant foods rich in phytoliths in the diets of twelve extant primates with wide variation in their molar enamel thickness. Additional dietary data from the literature provided the percentage of each primate’s diet made up of plants and of leaves. A statistical analysis of these variables showed that the amount of abrasive silica phytoliths in the diets of our sample primates correlated positively with the thickness of their molar enamel, constrained by the amount of leaves in their diet (R 2 = 0.875; p,.0006). Conclusions/Significance: The need to resist abrasion from phytoliths appears to be a key selective force behind the evolution of thick molar enamel in primates. The extreme molar enamel thickness of the teeth of the East African homini

To eat or not to eat? The diet of the endangered iberian wolf (Canis lupus signatus) in a human- dominated landscape in central Portugal

Livestock predation by large carnivores and their persecution by local communities are major conservation concerns. In order to prevent speculations and reduce conflicts, it is crucial to get detailed and accurate data on predators’ dietary ecology, which is particularly important in human dominated landscapes where livestock densities are high. This is the case of the endangered Iberian wolf in Portugal, an endemic subspecies of the Iberian Peninsula, which has seen its population distribution and abundance decline throughout the 20th century. Accordingly, the diet of the Iberian wolf was analyzed, using scat analysis, in a humanized landscape in central Portugal. From 2011 to 2014, a total of 295 wolf scats were collected from transects distributed throughout the study area, prospected on a monthly basis. Scat analysis indicated a high dependence of Iberian wolf on livestock. Domestic goat predominated the diet (62% of the scats), followed by cow (20%) and sheep (13%); the only wild ungulate present in the scat analysis was the wild boar (4% of the scats). Our results show that even though livestock constitute most part of wolves diet, different livestock species may represent different predation opportunities. We conclude that the high levels of livestock consumption may be a result of low diversity and density of wild ungulates that settles livestock as the only abundant prey for wolves. Our findings help on the understanding of the Iberian wolf feeding ecology and have implications for conflict management strategies. Finally, management implications are discussed and solutions are recommended

Estimation of gene flow into the Scandinavian brown bear population

Alexander Kopatz, Oddmund Kleven, Jonas Kindberg, Ilpo Kojola, Jouni Aspi, Göran Spong, Niclas Gyllenstrand, Love Dalén, Ida Fløystad, Snorre B. Hagen, Øystein Flagstad. 2019. Estimation of gene flow into the Scandinavian brown bear population. NINA Report 1618. Norwegian Institute for Nature Research. Background The populations of brown bear (Ursus arctos) in northern Europe have been recovering or are in the process of recovery from a severe demographic bottleneck. Especially in the main populations of Scandinavia and Finland, the number of individuals has been increasing substantially, compared to the population sizes estimated 20 years ago. Also, the populations have spatially expanded, putatively restoring connectivity and gene flow between these two, formerly separated populations. The Swedish Environmental Protection Agency (Naturvårdsverket) assigned a project to assess the connectivity and gene flow between the eastern and western parts of Fennoscandia, Finland and Scandinavia. Objective Our objective was to detect possible immigration of brown bears from eastern Fennoscandia, specifically Finland, into Scandinavia. Material and Methods For the first time with continuous sampling of brown bears, we assessed the population genetic structure and gene flow between the brown bear populations of Scandinavia and Finland. We based our analyses on the dispersing sex, male brown bears, as females tend to be philopatric. Our target area was the county of Norrbotten in northern Sweden, at the border to Finland and Norway, representing the most likely area for potential eastern immigrants into Sweden. Previous research did not reveal any influx from Finland into Sweden. However, brown bear samples from Norrbotten have to a very limited degree been included in earlier studies on genetic connectivity in the area. In addition to a large number of samples from Norrbotten and northern Finland, we included genotypes sampled in regions surrounding the target area: Västerbotten in Sweden, Troms and Finnmark in Norway and southern Finland. We utilized all samples and genotypes from male bears available, and, also, genotyped recently collected samples of male brown bears from the study area. Analyses on population genetic structure and gene flow among regions were based on 924 individual male brown bear STR-genotypes (12 short tandem repeats or microsatellite markers). In order to reveal patterns of male dispersal and the distribution of male linages we used brown bear samples genotyped with nine Y-chromosomal STRs from 826 males. Results Four different genetic clusters were identified. Assignment values for the different genotypes showed evidence of immigration of brown bears from Finland into Sweden for the first time. However, more individuals from Sweden dispersed into northern Finland than in the opposite direction. Reflective of the genetic structure, estimations resulted in asymmetrical rates of gene flow between Finland and Sweden; 1% immigration rate was detected from the east, northern Finland and Finnmark, into Norrbotten, while there was a rate of about 8% immigration from Norrbotten into northern Finland. Given the current population size, we estimated that 4.6 to 5.5 bears from the eastern populations immigrate into Norrbotten effectively per generation. Indirect methods, reflecting historical gene flow, estimated an effective number of migrants between 1.27 to 2.53 brown bears per generation between Norrbotten and Finland. The level of gene flow appears to surpass the suggested one-migrant-per-generation rule, an established standard or rule of thumb to minimize loss of genetic variation and thus counter genetic isolation. The assessment of male lineages using Y-chromosomal markers showed a similar picture with comparably more brown bears carrying haplotypes from Scandinavia in Finland, suggesting higher influx of individuals in west-east direction than the opposite way. Furthermore, STR- as well as Y-STR-analyses suggest the northernmost Norwegian county of Finnmark as another transition area or connectivity-corridor between the eastern and western brown bear populations in northern Europe. Conclusion Although levels of gene flow from Finland and Finnmark to Scandinavia appear to be relatively low, the results of this study showed immigration of brown bears from the east into Sweden for the first time. This influx might be indicative of further expansion of eastern populations and representative of an expansion front coming from the recovering Finnish brown bear population. However, it might also be that the now detected gene flow may be due to the continuous sampling applied for the first time in this study, which has not been the case in earlier studies assessing the connectivity between brown bear populations from the eastern and western parts of northern Europe.Alexander Kopatz, Oddmund Kleven, Jonas Kindberg, Ilpo Kojola, Jouni Aspi, Göran Spong, Niclas Gyllenstrand, Love Dalén, Ida Fløystad, Snorre B. Hagen, Øystein Flagstad. 2019. Estimering av genflyt til den Skandinaviske populasjoen av brunbjørn. NINA Rapport 1618. Norsk institutt for naturforskning. Bakgrunn og målsetning Etter en alvorlig demografisk flaskehals på 18- og 1900-tallet, har brunbjørnen (Ursus arctos) de siste tiårene tatt seg betydelig opp både i antall og utbredelse i Nord-Europa. Det er spesielt i Skandinavia og Finland at antall individer har økt kraftig, sammenlignet med bestandsstørrelsen bare 20 år tilbake. Økningen i antall har vært ledsaget av en betydelig ekspansjon av utbredel-sen, som potensielt er i ferd med å gjenopprette konnektvitet og genflyt mellom disse to, tidligere isolerte bestandene. Her rapporterer vi fra et prosjekt, iverksatt av Naturvårdsverket og støttet av Miljødirektoratet, der målsetningen var å undersøke konnektivitet og genflyt mellom våre østlige nabobestander og vestlige deler av Fennoskandia, dvs. identifisere eventuelle immigranter fra Finland i Skandinavia og undersøke i hvilken grad de bidrar i reproduksjon. Metoder Med kontinuerlig representasjon av prøver, som for første gang dekket store deler av Fennoskandia, undersøkte vi den populasjonsgenetiske strukturen og genflyt mellom brunbjørnbestandene i Sverige og Finland. Vi baserte våre analyser på hanner, siden hunnbjørner er såkalt filopatriske, dvs at de etablerer seg i eller i direkte tilknytning til morens hjemmeområde. Vårt fokusområde var Norrbotten, som grenser mot både Norge og Finland og representerer det mest sannsynlige området for potensielle immigranter fra øst. I tidligere studier har man ikke funnet immigranter fra Finland i Sverige. Prøver fra Norrbotten har imidlertid i svært liten grad inngått i disse studiene. I tillegg til et stort antall prøver fra Norrbotten, inkluderte vi genetiske data fra omkringliggende områder som Västerbotten, Troms, Finnmark og Finland. Vi brukte alle genetiske data som var tilgjengelig fra tidligere bjørneanalyser i området og genotypet i tillegg nyere innsamlet materiale fra det samme området. Totalt inkluderte vi genetiske data på 12 autosomale STR-markører (mikrosatelitter) for 924 hanner. For ytterligere analyse av hannenes migrasjon-mønster, inkluderte vi data fra ni Y-kromosom-markører fra 826 hanner, som spesifikt representerer hannenes slektslinjer. Resultater Fire genetiske grupper ble identifisert i Fennoskandia. Fra parametre for genetisk opphav dokumenterte vi for første gang immigranter fra Finland i Sverige. Dog var det betydelig flere bjørner med svensk opphav i Finland enn vice versa. I tråd med dette bekreftet våre analyser såkalt asymmetrisk genflyt, med 1 % immigrasjonsrate fra øst (Finland/Finnmark) til Norrbotten mot 8 % immigrasjon fra Norrbotten til nord-Finland. Gitt dagens bestandsstørrelse av brunbjørn i Fennoskandia, anslår vi en effektiv immigrasjon på mellom 4,6 og 5,5 reproduserende bjørner med østlig opphav til Norrbotten pr generasjon. Indirekte metoder, som i større grad reflekterer historisk genflyt, anslår et effektivt antall innvandrere mellom 1,27 til 2,53 bjørner. De anslåtte nivåene av immigrasjon synes å være tilstrekkelig i forhold til den anbefalte «en-migrant-per-genera-sjon»-regelen, en etablert standard for å unngå tap av genetisk variasjon og motvirke genetisk isolasjon. Y-kromosom dataene, som altså spesifikt representerer hannenes slektslinjer, viste et tilsvarende bilde med høyere immigrasjon til Finland fra Sverige enn vice versa. Et relativt stort antall bjørner i Finnmark hadde en østlig genetisk signatur, som viser at dette fylket har et stort potensiale som konnektivitetskorridor mellom våre østlige nabobestander og resten av Skandinavia. Konklusjon Selv om immigrasjon og genflyt fra Finland og Finnmark til resten av Skandinavia fortsatt framstår relativt begrenset, dokumenterer dataene i denne studien for første gang immigrasjon av bjørner med østlig opphav til Sverige. Dette kan tyde på at ekspansjonsfronten i en stadig økende finsk bjørnebestand har beveget seg vestover de siste årene. Tidsperspektivet her er dog noe usikkert, siden vi ikke kan utelukke at pågående genflyt nå endelig blir dokumentert som et resultat av en representativ prøveinnsamling, der vi for første gang hadde en kontinuerlig prøveinnsamling fra store deler av Fennoskandia

Data from: Genetic substructure and admixture as important factors in linkage disequilibrium-based estimation of effective number of breeders in recovering wildlife populations

The number of effective breeders (Nb) and effective population size (Ne) are population parameters reflective of evolutionary potential, susceptibility to stochasticity, and viability. We have estimated these parameters using the linkage disequilibrium-based approach with LDNE through the latest phase of population recovery of the brown bears (Ursus arctos) in Finland (1993–2010; N = 621). This phase of the recovery was recently documented to be associated with major changes in genetic composition. In particular, differentiation between the northern and the southern genetic cluster declined rapidly within 1.5 generations. Based on this, we have studied effects of the changing genetic structure on Nb and Ne, by comparing estimates for whole Finland with the estimates for the two genetic clusters. We expected a potentially strong relationship between estimate sizes and genetic differentiation, which should disappear as the population recovers and clusters merge. Consistent with this, our estimates for whole Finland were lower than the sum of the estimates of the two genetic clusters and both approaches produced similar estimates in the end. Notably, we also found that admixed genotypes strongly increased the estimates. In all analyses, our estimates for Ne were larger than Nb and likely reflective for brown bears of the larger region of Finland and northwestern Russia. Conclusively, we find that neglecting genetic substructure may lead to a massive underestimation of Nb and Ne. Our results also suggest the need for further empirical analysis focusing on individuals with admixed genotypes and their potential high influence on Nb and Ne