A genetic study of sika (Cervus nippon) in the New Forest and in the Purbeck region, southern England: is there evidence of recent or past hybridization with red deer (Cervus elaphus)?

Abstract

Sika Cervus nippon are native to Japan and East Asia but are now naturalized in many parks of the world, including Britain. In contrast to the substantial body of research on the extent of hybridization between sika and red deer Cervus elaphus in Scottish populations, there has been little genetic analysis of the English populations of sika. Sika in England still have a patchy and discontinuous distribution; populations are thus still genetically isolated and may be expected to show higher variability in genetic type. The current paper uses DNA-based techniques to explore the genetic composition of sika in the New Forest (Hampshire) and that of sika from the largest population in England, in the Purbeck region (Dorset). The study aims were to determine whether New Forest sika show signs of recent interbreeding with New Forest red deer populations, whether New Forest sika are genetically distinct from Purbeck sika, and whether New Forest and Purbeck sika show evidence of past hybridization or whether they are pure (non-hybrid) strains. Microsatellite analysis was used to compare the genetic profiles of individual deer. Results showed that sika and red deer in the New Forest were genetically distinct, indicating that there is no large-scale in situ hybridization occurring between these feral populations. In terms of overall genetic composition, there was no significant difference between the sika in the New Forest and Purbeck. However, a more detailed analysis found that New Forest sika showed a lower level of introgression with red deer compared with the Purbeck sika. We conclude that, overall, the New Forest sika deer do appear to be more genetically pure bred than the Purbeck sika.

Hybridization between Crocodylus acutus and Crocodylus moreletii in the Yucatan Peninsula: II. evidence from microsatellites

“…Molecular markers also have been used to detect, quantify and to determine the age of hybridization and introgression events (Diaz et al, 2006;Lorenzen et al, 2006;Barilani et al, 2007); these events can have serious biological implications that affect evolutionary trajectories of species (Arnold, '92;Grant et al, 2005). Conservation and management of threatened species are hindered by the occurrence of hybridization, whether owing to natural or anthropogenic causes (Allendorf et al, 2001).…”

Red and sika deer in the British Isles, current management issues and management policy

“…The four British populations clustered with the Nagasaki population. Similarly, Díaz et al (2006) demonstrated high similarity in microsatellite genotypes between the New Forest and Dorset sika (both southern England) and sika from Nagasaki. This finding agrees with historical information, in that Nagasaki was the only Japanese port open to trade in the mid 19th Century (Goodman et al 2001).…”

“…These considerations do not rule out some impurity in the introduced sika, but they do suggest it was not extensive. Finally, we note that despite generally low levels of genetic variation in sika, there is nevertheless some genetic variation between sika populations subjected to either molecular genetic (Swanson 1999;Díaz et al 2006) or morphometric (Putman and Hunt 1994) analysis. While this variation could be attributed to different levels of low-grade introgression from red, it could also be due to the initial genetic variation associated with the individuals used to found the populations during the various introduction events.…”

“…Ratcliffe (1987a) offers a detailed review of the history of introduction and the subsequent spread of the species through Great Britain; see also Lever (1977) and Díaz et al (2006) for notes on the origins of populations in southern England.…”

“…Hybridisation between red and sika has been documented in both the United Kingdom and the Republic of Ireland (e.g. Harrington 1973;Putman and Hunt 1994;Abernethy 1994;Goodman et al 1999;Díaz et al 2006;Pemberton et al 2006;Senn and Pemberton, in press) and in the Czech Republic ; Zima et al 1990), and there is concern about the potential for hybridisation elsewhere in Continental Europe (Wotchikowsky 2009;Bartoš 2009). Britain perhaps has the greatest experience of the problems associated with expanding populations of sika, and it is suggested that an exploration of current problems and policies within the British Isles may be helpful in guiding policy elsewhere in Europe where sika populations are currently on the increase.…”