Colonization of the Scottish islands via long-distance Neolithic transport of red deer (Cervus elaphus)

The 10,000-year biocultural history of fallow deer and its implications for conservation policy

Over the last 10,000 y, humans have manipulated fallow deer populations with varying outcomes. Persian fallow deer (Dama mesopotamica) are now endangered. European fallow deer (Dama dama) are globally widespread and are simultaneously considered wild, domestic, endangered, invasive and are even the national animal of Barbuda and Antigua. Despite their close association with people, there is no consensus regarding their natural ranges or the timing and circumstances of their human-mediated translocations and extirpations. Our mitochondrial analyses of modern and archaeological specimens revealed two distinct clades of European fallow deer present in Anatolia and the Balkans. Zooarchaeological evidence suggests these regions were their sole glacial refugia. By combining biomolecular analyses with archaeological and textual evidence, we chart the declining distribution of Persian fallow deer and demonstrate that humans repeatedly translocated European fallow deer, sourced from the most geographically distant populations. Deer taken to Neolithic Chios and Rhodes derived not from nearby Anatolia, but from the Balkans. Though fallow deer were translocated throughout the Mediterranean as part of their association with the Greco-Roman goddesses Artemis and Diana, deer taken to Roman Mallorca were not locally available Dama dama, but Dama mesopotamica. Romans also initially introduced fallow deer to Northern Europe but the species became extinct and was reintroduced in the medieval period, this time from Anatolia. European colonial powers then transported deer populations across the globe. The biocultural histories of fallow deer challenge preconceptions about the divisions between wild and domestic species and provide information that should underpin modern management strategies.

Genetic traces of dispersal and admixture in red deer (Cervus elaphus) populations from the Carpathian Basin

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 south-western and the north-eastern 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.

Mining the red deer genome (CerEla1.0) to develop X-and Y-chromosome-linked STR markers

Microsatellites are widely applied in population and forensic genetics, wildlife studies and parentage testing in animal breeding, among others, and recently, high-throughput sequencing technologies have greatly facilitated the identification of microsatellite markers. In this study the genomic data of Cervus elaphus (CerEla1.0) was exploited, in order to identify microsatellite loci along the red deer genome and for designing the cognate primers. The bioinformatics pipeline identified 982,433 microsatellite motifs genome-wide, assorted along the chromosomes, from which 45,711 loci mapped to the X- and 1096 to the Y-chromosome. Primers were successfully designed for 170,873 loci, and validated with an independently developed autosomal tetranucleotide STR set. Ten X- and five Y-chromosome-linked microsatellites were selected and tested by two multiplex PCR setups on genomic DNA samples of 123 red deer stags. The average number of alleles per locus was 3.3, and the average gene diversity value of the markers was 0.270. The overall observed and expected heterozygosities were 0.755 and 0.832, respectively. Polymorphic Information Content (PIC) ranged between 0.469 and 0.909 per locus with a mean value of 0.813. Using the X- and Y-chromosome linked markers 19 different Y-chromosome and 72 X-chromosome lines were identified. Both the X- and the Y-haplotypes split to two distinct clades each. The Y-chromosome clades correlated strongly with the geographic origin of the haplotypes of the samples. Segregation and admixture of subpopulations were demonstrated by the use of the combination of nine autosomal and 16 sex chromosomal STRs concerning southwestern and northeastern Hungary. In conclusion, the approach demonstrated here is a very efficient method for developing microsatellite markers for species with available genomic sequence data, as well as for their use in individual identifications and in population genetics studies.

Red deer in Iberia: Molecular ecological studies in a southern refugium and inferences on European postglacial colonization history

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.

Introgression of exotic Cervus (nippon and canadensis) into red deer (Cervus elaphus) populations in Scotland and the English Lake District

Since the mid-19th century, multiple introductions of Japanese sika deer (Cervus nippon nippon) and North American wapiti (C. canadensis) have taken place in the British Isles. While wapiti have generally been unsuccessful, sika have been very successful, especially in Scotland where they now overlap at least 40% of the range of native red deer (C. elaphus). Hybridization between these two species and red deer has been demonstrated in captivity and in the wild. Using a panel of 22 microsatellite loci that are highly diagnostic between red deer and sika, and moderately diagnostic between red deer and wapiti, we investigated the extent of introgression between these species in 2,943 deer sampled from around Scotland and from the English Lake District using the Bayesian clustering software STRUCTURE. We also used a diagnostic mitochondrial marker for red deer and sika. Our survey extends previous studies indicating little introgression of wapiti nuclear alleles into red deer, in particular in Northern Scotland, Kintyre, and the Lake District. We found a new area of extensive sika introgression in South Kintyre. In the North Highlands, we show for the first time geographically scattered evidence of past hybridization followed by extensive backcrossing, including one red-like individual with sika introgression, two sika-like individuals with red deer introgression, and six individuals that were apparently pure sika at the nuclear markers assessed but which carried red deer mitochondria. However, there has not been a collapse of assortative mating in this region. Similarly, in the English Lake District red deer, we found only traces of past sika introgression. No sika alleles were detected in the Central Highlands or the Hebridean red deer refugia. We make suggestions for management to prevent further spread of sika alleles into red deer and vice versa.

Imperial trophy or island relict? A new extinction paradigm for Père David's deer: a Chinese conservation icon

Determining the 'dynamic biogeography' of range collapse in threatened species is essential for effective conservation, but reconstruction of spatio-temporal patterns of population vulnerability and resilience can require use of non-standard ecological data such as historical archives. Père David's deer or milu, one of the few living mammal species that has become extinct in the wild, is historically known only from a small captive herd of unknown provenance that survived until 1900 in the Imperial Hunting Park near Beijing, from which all living individuals are descended. Using ancient DNA analysis, we demonstrate that two fawns collected in 1868 from Hainan Island, off the southern Chinese mainland, represent the only known wild milu specimens and were sampled from probably the last wild population. The Hainan milu population shows extremely low genetic differentiation from descendants of the Beijing herd, suggesting that this now-extinct population may have been the source of the captive herd. This revised extinction model refutes the supposed long-term survival of a captive milu herd for centuries or millennia after final extinction of wild populations, highlighting the vulnerability of remnant mammal populations in the absence of proactive management and the importance of historical museum collections for providing unique new insights on evolution, biogeography and conservation. Milu experienced a pattern of final population persistence on an island at the periphery of their former range, consistent with the 'range eclipse' or 'contagion' model of range collapse, and matching the spatial extinction dynamics of other extinct mammals such as the thylacine and woolly mammoth.

Phylogeography of the Tyrrhenian red deer (Cervus elaphus corsicanus) resolved using ancient DNA of radiocarbon-dated subfossils

We present ancient mitochondrial DNA analyses of 31 complete cytochrome b gene sequences from subfossil red deer remains from the Tyrrhenian islands (Corsica and Sardinia) and mainland Italy in a European-wide phylogeographic framework. Tyrrhenian and North African red deer, both going back to human introductions, were previously the only red deer to harbour the mitochondrial B lineage whose origin, however, remained unknown. Our ancient Italian samples from the central part of the peninsula that were radiocarbon-dated to an age of ca. 6300 to 15 600 cal BP all showed B haplotypes, closely related or even identical to those found on Sardinia. Genetic diversity in the mainland population was considerably higher than on the islands. Together with palaeontological evidence our genetic results identify the Italian Peninsula as the ultimate origin of the B lineage and thus the Tyrrhenian and North African red deer. This is in line with previous biogeographic findings that uncovered distinct intraspecific phylogeographic lineages in Italian mammals, underlining Italy’s status as a hotspot of European mammalian diversity.