Phenotypic correlates of hybridisation between red and sika deer (genus Cervus)

Abstract

Summary 1.Hybridisation with an invasive species has the potential to alter the phenotype and hence the ecology of a native counterpart. 2. Here data from populations of native red deer Cervus elaphus and invasive sika deer Cervus nippon in Scotland is used to assess the extent to which hybridisation between them is causing phenotypic change. This is done by regression of phenotypic traits against genetic hybrid scores. 3. Hybridisation is causing increases in the body weight of sika-like deer and decreases in the body weight of red-like females. Hybridisation is causing increases in jaw length and increases in incisor arcade breadth in sika-like females. Hybridisation is also causing decreases in incisor arcade breadth in red-like females. 4. There is currently no evidence that hybridisation is causing changes in the kidney fat weight or pregnancy rates of either population. 5. Increased phenotypic similarity between the two species is likely to lead to further hybridisation. The ecological consequences of this are difficult to predict.

Variability of Female Responses to Conspecific vs. Heterospecific Male Mating Calls in Polygynous Deer: An Open Door to Hybridization?

“…Male sika deer moans may therefore be perceived as attractive, exaggerated, or novel versions of male red deer roars by some female red deer receivers, although with increased sympatry between these species, female red deer may improve their discrimination decisions for male mating calls through reproductive character displacement of female choice if fitness costs are associated with hybrid matings [18], [59]. Studies on captive animals show no obvious physiological disadvantage to hybrids [29], [60] and studies of free-ranging animals suggest that initial pairings between red and sika deer occasionally produce fertile offspring [34] and that female hybrids do not have lower pregnancy rates than the parent species [61]. However, to our knowledge the overall fitness of hybrids has not yet been systematically contrasted with that of either parent species.…”

A survey of the hybridisation status of Cervus deer species on the island of Ireland

“…In a wild red-sika hybrid zone in Kintyre, Argyll (Scotland), following genetic analysis, the proportion of red deer ancestry was estimated ('Q', see Methods) and its influence on carcass traits was analysed (Senn et al 2010). Carcass weight, jaw length and incisor arcade breadth were all linearly related to Q, i.e.…”

“…Carcass weight, jaw length and incisor arcade breadth were all linearly related to Q, i.e. the more red deer genome present, the larger the individual (Senn et al 2010). On New Zealand deer farms which predominantly farm red deer, wapiti have been deliberately hybridised and introgressed to increase carcass and antler size of red deer (Moore and Littlejohn 1989).…”

Impact of interspecific relations between native red deer (Cervus elaphus) and introduced sika deer (Cervus nippon) on their rutting season in the Doupovské hory Mts.

“…The spreading of certain deer species across the world and their influence on the environment are described as very unsettling (Takatsuki 2009) Competition for food, the related damage to agricultural and forest stands, and especially spontaneous hybridization with the red deer are considered to be the main problematic interactions of the sika deer with the autochthonous species (Bartoš, Žirovnický 1982;Gehle, Herzog 1998;Goodman et al 1999). Crossbreeding with red deer has been declared one of the main threats (Bartoš 2009;Senn et al 2010;Biedrzycka et al 2012), and generally hybridization with autochthonous species is considered to be one of the greatest problems for global biodiversity (Arnold 2004). Hybridization in free-ranging areas has been molecularly demonstrated only at a few sites (McDevitt et al 2009;Senn et al 2010), and mainly in Great Britain.…”

“…Crossbreeding with red deer has been declared one of the main threats (Bartoš 2009;Senn et al 2010;Biedrzycka et al 2012), and generally hybridization with autochthonous species is considered to be one of the greatest problems for global biodiversity (Arnold 2004). Hybridization in free-ranging areas has been molecularly demonstrated only at a few sites (McDevitt et al 2009;Senn et al 2010), and mainly in Great Britain. Nevertheless, signs of hybridization are becoming increasingly apparent in other areas too.…”