Research by Edinburgh University scientists has found that hybridisation between native red deer and introduced Japanese sika deer is changing the size of both species.

The sika deer was introduced to deer parks around Scotland in the late 19th Century but escaped, spread, and now occupies much of the range of the Scottish red deer. Despite the fact that sika are much smaller in size, the two species can hybridise and the hybrids are fertile. Earlier this year the scientists used DNA tests to show that in Argyll most animals were sika or red deer, but in one area more than 40% of the deer are hybrids.

The same team has now compared their genetic results with weights and measures collected when the deer were sampled, and found that sika-like hybrids are larger than pure sika and red-like hybrids are smaller than pure red. The new finding is a concern because intermediate-sized animals may not be so choosy who they mate with, leading to further hybridisation. Also, many aspects of a species’ ecology go with its size – for example what it eats and how often the females breed, so it is possible that a new type of deer with new ecological impacts will emerge.

Professor Josephine Pemberton, whose lab did the research, said:

“To date, it has not been clear what the practical effects of hybridisation on Scottish red deer are. Our research fills this gap in knowledge and suggests that ‘the Mongrel of the Glens’ is a real possibility.”

The research, which was funded by the Natural Environment Research Council and the Macaulay Institute, and used samples and data collected by Forestry Commission Scotland, is published in the Journal of Animal Ecology.

Read more about this research at BBC online:

http://news.bbc.co.uk/earth/hi/earth_news/newsid_8413000/8413647.stm