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Consequences for genetic diversity and population performance of introducing continental red deer into the northern distribution range

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Abstract

For several centuries, game management has involved translocations of non-native individuals of many species to reinforce local native populations. However, there are few quantitative studies of potentially negative effects on population viability as expected when taxa with different local adaptations hybridise. The European red deer has been subject to particularly many translocations. Around 1900, a total of 17 red deer of Hungarian (Cervus elaphus hippelaphus) and German (C. e. germanicus) origin were introduced onto the island of Otterøya in Norway where few native red deer (C. e. atlanticus) remained (n~13). To assess interbreeding, the present stock on Otterøya and the indigenous Norwegian and Hungarian populations were characterised in 14 microsatellite loci and in the control region of mtDNA. An intermediate level of genetic variation in the Otterøya population and the presence of population specific alleles from both the indigenous Norwegian and the Hungarian population demonstrate that the introduced red deer interbred with the native. Even distributions of one indigenous and one non-indigenous mtDNA haplotype in the Otterøya population and two point estimates of admixture indicate similar genetic contributions from the two parental populations into the hybrid stock. Low numbers of migrants identified with Bayesian assignment tests demonstrate low recent gene flow from Otterøya into the Norwegian mainland population. The Otterøya hybrid stock has grown vastly in numbers during recent decades, suggesting a high population viability. We observed that the body mass of red deer on Otterøya was similar or greater than in adjacent indigenous Norwegian stocks, indicating that population performance has not been reduced in the hybrid stock and that gene flow probably has not had any negative effects. KeywordsTranslocation-Hybrid stock-Introgression-Admixture-Dispersal
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... In effect, the patterns of genetic discontinuities would be visible across the zone, as well documented for species like the European hedgehog, brown bear and roe deer (e.g., Hewitt, 2004;Sommer and Zachos, 2009 The red deer is one of the most widespread, most abundant and most important game species in Europe (Ludt et al., 2004;Milner et al., 2006;Zachos and Hartl, 2011). As a result, red deer have been extensively managed, introduced, restocked, and selectively hunted throughout its history and distribution area (Frantz et al., 2006;Milner et al., 2006;Csányi and Lehoczki, 2010;Haanes et al., 2010;Zachos and Hartl, 2011;Carden et al., 2012;Stanton et al., 2016), and are farmed for meat and for antler products (Csányi and Lehoczki, 2010;Wada et al., 2010;Zachos and Hartl, 2011;Frank et al., 2016). The species has been the subject of several studies with a phylogeographic focus at local Feulner et al., 2004;Haanes et al., 2010;Carden et al., 2012;Fickel et al., 2012;Karaiskou et al., 2014;Krojerová-Prokešová et al., 2015;Markov et al., 2015;Borowski et al., 2016;Carranza et al., 2016;Stanton et al., 2016) as well as larger geographical scales (Ludt et al., 2004;Skog et al., 2009;Niedziałkowska et al., 2011;Meiri et al., 2013). ...
... As a result, red deer have been extensively managed, introduced, restocked, and selectively hunted throughout its history and distribution area (Frantz et al., 2006;Milner et al., 2006;Csányi and Lehoczki, 2010;Haanes et al., 2010;Zachos and Hartl, 2011;Carden et al., 2012;Stanton et al., 2016), and are farmed for meat and for antler products (Csányi and Lehoczki, 2010;Wada et al., 2010;Zachos and Hartl, 2011;Frank et al., 2016). The species has been the subject of several studies with a phylogeographic focus at local Feulner et al., 2004;Haanes et al., 2010;Carden et al., 2012;Fickel et al., 2012;Karaiskou et al., 2014;Krojerová-Prokešová et al., 2015;Markov et al., 2015;Borowski et al., 2016;Carranza et al., 2016;Stanton et al., 2016) as well as larger geographical scales (Ludt et al., 2004;Skog et al., 2009;Niedziałkowska et al., 2011;Meiri et al., 2013). Based on previous studies of mitochondrial DNA (mtDNA) sequences, three deeply divergent lineages of red deer are known within Europe, enabling classification of individuals into Iberian (termed haplogroup A sensu Skog et al., 2009), Balkan (haplogroup C) and Mediterranean (haplogroup B) groups, suggesting retraction into three separate refugia during the last glaciation, the Iberian Peninsula, the Balkans and the Italian Peninsula (Ludt et al., 2004;Skog et al., 2009;Meiri et al., 2013;Karaiskou et al., 2014;Carranza et al., 2016). ...
... Their occurrence can be the result of natural immigration; however, the influence of human-engineered translocations could also -at least partially -justify the observed pattern. As an important game species, red deer have been translocated for centuries or even millennia, and such activities are still being carried out, often illegally Frantz et al., 2006;Csányi and Lehoczki, 2010;Haanes et al., 2010;Carden et al., 2012;Karaiskou et al., 2014;Stanton et al., 2016). Translocations, however, had little impact on the large-scale phylogenetic pattern, at least as far as the mitochondrial genome, i.e. the maternal line, is concerned (Ludt et al., 2004;Skog et al., 2009;Niedziałkowska et al., 2011;Meiri et al., 2013;Krojerová-Prokešová et al., 2015;Borowski et al., 2016). ...
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Changes in the distributional range of European red deer (Cervus elaphus) during the Quaternary and the recolonization of Europe from different refugia, created a clear phylogeographical pattern. In Central Europe, two distinct − Iberian and Balkan − lineages of European red deer are present; however, this suture zone has not yet been studied in detail. The sequences of the complete mitochondrial control region were used to investigate the genetic structure of the red deer in the Carpathian Basin, a region where both lineages are expected to be present. We sequenced the complete control region of 96 red deer samples, discovered 39 haplotypes, and found high levels of haplotype diversity (H = 0.806 for the southwestern and H = 0.954 for the northeastern population). We discovered a high number of haplotypes belonging to both lineages, as well as unique haplotypes, which do not fit into described haplotypes. This is in accordance with previous assumptions that the Carpathian Basin is a suture zone between the Iberian and the Balkan red deer haplogroups.
... The genetic structure of large mammal species is affected by natural and anthropogenic factors. Anthropogenic impacts like selective hunting, translocations, and habitat destruction/fragmentation can blur natural patterns of genetic diversity and relationships (Frantz et al. 2006;Haanes et al. 2010;Dellicour et al. 2011;Carden et al. 2012;Stanton et al. 2016;Zachos et al. 2016;Galarza et al. 2017;Queirós et al. 2020). Such impacts, particularly in game species, can cause the disintegration of populations into several subpopulations with a more or less pronounced genetic exchange Willems et al. 2016;Iacolina et al. 2019;Mihalik et al. 2020). ...
... The red deer (Cervus elaphus L. 1758) is one of the most widespread and valuable European game species (Ludt et al. 2004;Milner et al. 2006). Consequently, its populations have been extensively managed, introduced, restocked, and selectively hunted for centuries or even millennia (Martínez et al. 2002;Haanes et al. 2010;Carden et al. 2012;Rivrud et al. 2013;Queirós et al. 2014;Hoffmann et al. 2016;Stanton et al. 2016;Frantz et al. 2017;Galarza et al. 2017). Furthermore, during the last decades, the keeping of deer in enclosures has spread all over the world, and the species is farmed for venison and antler products (Milner et al. 2006;Wada et al. 2010;Zachos and Hartl 2011;Bana et al. 2018). ...
... Studies on the genetic structure of European mammals, including red deer, based on mitochondrial DNA (mtDNA) sequences (Ludt et al. 2004;Skog et al. 2009;Niedziałkowska et al. 2011;Meiri et al. 2013;Frank et al. 2017;Rey-Iglesia et al. 2017;Queirós et al. 2019) as well as on microsatellites (Zachos et al. 2016;Frantz et al. 2017;Queirós et al. 2019) have shown the large-scale genetic pattern shaped by the Late Pleistocene and Holocene glacial-interglacial cycles. Local or regional red deer populations have also been extensively studied from a population genetic point of view, often taking into account anthropogenic influences (Kuehn et al. 2003;Zachos et al. 2003;Frantz et al. 2006;Hajji et al. 2008;Haanes et al. 2010;Dellicour et al. 2011;Radko et al. 2014;Krojerová-Prokešová et al. 2015;Borowski et al. 2016;Carranza et al. 2016;Hoffmann et al. 2016;Willems et al. 2016;Galarza et al. 2017). ...
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After the last glacial, the Carpathian Basin was repopulated from either eastward or northward colonisation routes for various species; one of these was the emblematic member of the European megafauna, the red deer, Cervus elaphus. We analysed 303 red deer individuals from the middle of the region, in seven Hungarian game reserves, at ten microsatellite loci (C01, C229, T26, T108, T123, T156, T172, T193, T501, T507), to investigate the genetic diversity of these subpopulations. We discovered high levels of genetic diversity of red deer subpopulations; allelic richness values ranging 4.99-7.01, observed heterozygosity 0.729-0.800, polymorphic information content 0.722-0.806, and Shannon's information index 1.668-2.064. Multi-locus analyses indicated population admixtures of various degrees that corresponded to geographical location, and complex genetic structures were shown by clustering. Populations in the southwestern and the northeastern parts of the region formed two highly separated groups, and the red deer from populations in between them were highly admixed (in western Pannonia/Transdanubia, where the Danube flows into the Carpathian Basin). This pattern corresponds to the distribution of mitochondrial as well as Y-chromosome lineages. Assignment tests showed that a large fraction of individuals (29.4%) are found outside of their population of origin, indicating that the dispersal of red deer is rather common, which could be expected considering the life course of the species.
... Deer have cultural, ecological and an increasing economic importance. Being among the most important game animals for trophies, their populations have been managed, translocated and selectively hunted throughout their history and distribution area [26][27][28][29][30]. Recently a worldwide "deer industry" has been developed, whereby animals are farmed for venison and to some extent for antler products [31][32][33]. ...
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... The impact of anthropogenic hybridization on the evolution of organisms is difficult to evaluate in natural populations because it entails a long term monitoring of several fitnessrelated traits (Allendorf et al., 2001). Nevertheless, it is well known that hybridization may reduce fitness, disrupt gene-adapted complexes and alter the genetic structure of populations (Muhlfeld et al., 2009;Haanes et al., 2010;Senn et al., 2010;Huisman et al., 2016). However, what are the hybridization effects on the genetic diversity of populations? ...
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Anthropogenic hybridization is one of the greatest threats to global biodiversity. It incites human-mediated gene flow between non-native/exotic and native taxa, which can have irreversible effects on native species or locally adapted populations, eventually leading to extinction. The red deer, Cervus elaphus, is a game species that, due to its extraordinary economic value, has been introduced in several regions throughout Europe. However, the consequences of those introductions on native populations, namely on their genetic background, have been poorly addressed. This study is focused on the Iberian Peninsula and aims to: (i) assess the extent of anthropogenic hybridization/introgression of introduced red deer into the native Iberian populations; (ii) evaluate the impact of red deer management regimes on the observed hybridization/introgression patterns; and (iii) assess how hybridization/introgression influence the current genetic diversity of native Iberian populations. A set of 11 microsatellites and a 329 bases pair fragment of the mitochondrial D-loop gene were used to estimate nuclear admixture and mitochondrial introgression in 1,132 individuals sampled across 46 red deer populations throughout Iberia. A Bayesian approach implemented in the STRUCTURE program was employed to investigate the proportion of admixture between native populations and non-native red deer. Results showed that 17% of individuals presented signs of non-native recent ancestors and 10.1% had non-native mitochondrial haplotypes, reaching an overall hybridization/introgression rate of 23%. Non-native or hybrid individuals were found throughout 40 Iberian red deer populations, and the percentages per population varied between 3.3 and 75.0%, independently of the management regime. Mitochondrial introgression was observed across 15 Iberian red deer populations, being more frequent in free-ranging individuals (16.2%) than in fenced populations (9.2%) but was completely absent from public-owned populations. Nuclear genetic diversity correlated positively with the proportion of hybrid individuals in public-owned populations. The genetic footprint of historical and current human-mediated translocations of non-native red deer into the Iberian Peninsula is evidenced in this study, highlighting the need to implement effective measures to avoid such practices both in Portugal and Spain, in order to preserve the endogenous genetic patrimony of the Iberian red deer populations.
... As such, red deer have been the target of many population and 1 3 conservation genetic studies analyzing the genetic diversity and population structure in human-dominated landscapes (e.g., Kuehn et al. 2003;Pérez-Espona et al. 2008Fickel et al. 2012Frantz et al. 2017). The aims of these studies varied, and included the quantification of genetic diversity in isolated and sometimes inbred populations (e.g., Zachos et al. 2007), estimating the amount and genetic consequences of translocations (e.g., Pérez-Espona et al. 2009;Haanes et al. 2010), or characterizing the genetic impacts of postglacial recolonization (e.g., Krojerova-Prokesova et al. 2015). ...
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Red deer (Cervus elaphus) throughout central Europe are influenced by different anthropogenic activities including habitat fragmentation, selective hunting and translocations. This has substantial impacts on genetic diversity and the long-term conservation of local populations of this species. Here we use genetic samples from 480 red deer individuals to assess genetic diversity and differentiation of the 12 administrative management units located in Schleswig Holstein, the northernmost federal state in Germany. We applied multiple analytical approaches and show that the history of local populations (i.e., translocations, culling of individuals outside of designated red deer zones, anthropogenic infrastructures) potentially has led to low levels of genetic diversity. Mean expected heterozygosity was below 0.6 and we observed on average 4.2 alleles across 12 microsatellite loci. Effective population sizes below the recommended level of 50 were estimated for multiple local populations. Our estimates of genetic structure and gene flow show that red deer in northern Germany are best described as a complex network of asymmetrically connected subpopulations, with high genetic exchange among some local populations and reduced connectivity of others. Genetic diversity was also correlated with population densities of neighboring management units. Based on these findings, we suggest that connectivity among existing management units should be considered in the practical management of the species, which means that some administrative management units should be managed together, while the effective isolation of other units needs to be mitigated.
... The new D-loop sequences (670 bp) were aligned together with 624 sequences retrieved from GenBank, comprising the representative haplotypes from the majority of red deer studies published throughout Europe and North Africa up to 2017 [13,17,24,30,31,34,[64][65][66][67][68][69][70][71][72][73][74][75][76][77][78][79][80][81][82]. Phylogeographic analyses were performed at two geographical scales: the central and northern European level and the Iberian level. ...
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The red deer (Cervus elaphus) is a widespread wild ungulate in Europe that has suffered strong anthropogenic impacts over their distribution during the last centuries, but also at the present time, due its economic importance as a game species. Here we focus on the evolutionary history of the red deer in Iberia, one of the three main southern refugial areas for temperate species in Europe, and addressed the hypothesis of a cryptic refugia at higher latitudes during the Last Glacial Maximum (LGM). A total of 911 individuals were sampled, genotyped for 34 microsatellites specifically developed for red deer and sequenced for a fragment of 670 bp of the mitochondrial (mtDNA) D-loop. The results were combined with published mtDNA sequences, and integrated with species distribution models and historical European paleo-distribution data, in order to further examine the alternative glacial refugial models and the influence of cryptic refugia on European postglacial colonization history. Clear genetic differentiation between Iberian and European contemporary populations was observed at nuclear and mtDNA levels, despite the mtDNA haplotypes central to the phylogenetic network are present across western Europe (including Iberia) suggesting a panmictic population in the past. Species distribution models, fossil records and genetic data support a timing of divergence between Iberian and European populations that overlap with the LGM. A notable population structure was also found within the Iberian Peninsula, although several populations displayed high levels of admixture as a consequence of recent red deer translocations. Five D-loop sub-lineages were found in Iberia that belong to the Western European mtDNA lineage, while there were four main clusters based on analysis of nuclear markers. Regarding glacial refugial models, our findings provide detailed support for the hypothesis that red deer may have persisted in cryptic northern refugia in western Europe during the LGM, most likely in southern France, southern Ireland, or in a region between them (continental shelf), and these regions were the source of individuals during the European re-colonization. This evidence heightens the importance of conserving the high mitochondrial and nuclear diversity currently observed in Iberian populations.
... Apart from the species' European-wide phylogeography, local or regional red deer stocks have also been intensively studied from a population genetic point of view, often taking into account human impacts (Carranza, Salinas, de Andrés, & Pérez-González, 2016;Frantz, Hamann, & Klein, 2008;Haanes, Røed, Flagstad, & Rosef, 2010;Haanes, Røed, Mysterud, Langvatn, & Rosef, 2010;Hoffmann, Johannesen, & Griebeler, 2016;Kuehn, Haller, Schroeder, & Rottmann, 2004;Kuehn, Schroeder, Pirchner, & Rottmann, 2003;Niedziałkowska, Jędrzejewska, Wójcik, & Goodman, 2012;Zachos, Althoff, Steynitz, Eckert, & Hartl, 2007). Some of these studies have identified clear phylogeographic outliers (e.g., a Sardinian haplotype in the British Isles, Nussey, Pemberton, Donald, & Kruuk, 2006; a few more phylogeographic outliers can be found in Skog et al., 2009), which is conclusive evidence of long-distance translocations. ...
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Game species like the red deer have been subjected to anthropogenic impacts for centuries. Translocations are often carried out—sometimes illegally—not only for sporting purposes, but also to increase trophy quality, reduce inbreeding, or mitigate bottlenecks after excessive persecution. Apart from the blurring of large-scale genetic structure, translocations without adequate quarantine measure risk introducing pathogens into potentially immunologically naïve populations. It is therefore important to understand the frequency of clandestine translocations. Identification of non-autochthonous animals and their potential origin is often difficult and, in red deer, has been hampered by the lack of large-scale genotypic datasets for comparison. In the present study, we make use of a recently published European-wide microsatellite dataset to detect and quantify the presence of non-autochthonous red deer in a large population sample (n = 1,780) from Central Europe (Belgium). Using factorial correspondence analysis, assignment tests and Bayesian clustering algorithms we arrive at an estimate of 3.7% non-autochthonous animals (or their descendants). Some of these animals were assigned to a nearby French population and may have immigrated into Belgium naturally, but the large majority must have been introduced by humans. Our analysis pointed to the British Isles and Germany/Poland as the potential origin of many introduced deer, regions known to have been source populations for translocations in Europe and beyond. We found evidence for recreational hunters using carcasses from farmed deer to fulfill mandatory hunting quotas. Our study is the first to quantify the extent of human-mediated introductions in a European game species at such a large scale with large and representative sample sizes.
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... As such, red deer have been the target of many population and 1 3 conservation genetic studies analyzing the genetic diversity and population structure in human-dominated landscapes (e.g., Kuehn et al. 2003;Pérez-Espona et al. 2008Fickel et al. 2012Frantz et al. 2017). The aims of these studies varied, and included the quantification of genetic diversity in isolated and sometimes inbred populations (e.g., Zachos et al. 2007), estimating the amount and genetic consequences of translocations (e.g., Pérez-Espona et al. 2009;Haanes et al. 2010), or characterizing the genetic impacts of postglacial recolonization (e.g., Krojerova-Prokesova et al. 2015). ...
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The first edition of this book has established itself as one of the leading references on generalized additive models (GAMs), and the only book on the topic to be introductory in nature with a wealth of practical examples and software implementation. It is self-contained, providing the necessary background in linear models, linear mixed models, and generalized linear models (GLMs), before presenting a balanced treatment of the theory and applications of GAMs and related models. The author bases his approach on a framework of penalized regression splines, and while firmly focused on the practical aspects of GAMs, discussions include fairly full explanations of the theory underlying the methods. Use of R software helps explain the theory and illustrates the practical application of the methodology. Each chapter contains an extensive set of exercises, with solutions in an appendix or in the book’s R data package gamair, to enable use as a course text or for self-study.