What is native?
There is one question that is guaranteed to spark debate among any Irish scientists researching land mammals. Three short words that could make you re-evaluate how you perceive the animals you grew up with. What is native? As part of Heritage Week, I spoke to UCD researcher Dr. Allan McDevitt, Co-Chair of the upcoming AIMS 2012 conference (info below), about his research and the quest to answer this “million dollar question”.
So what do you think is native? Among others the badger, pigmy shrew, stoat, Irish hare and red squirrel may come to mind. As an island nation all of our land mammals arrived here from Britain or Europe at some point in the past. So at what instant do we start issuing them Irish passports? McDevitt proposes “any animal that has been here as long as people have. Whatever animals they brought with them and their direct descendents [are what] we would call Irish”.
So where is the controversy? All we need to do is look at the fossil record and determine which are about 5,000 years or older… walla… we have a native species! Adhering to this definition would haul an iconic ‘native’ mammal into the immigration office. McDevitt reveals that the “red squirrel is in no way native. There is no evidence of it in the fossil record before the 16th century”. What about the posters on every nature table? Our nation’s hatred of the grey squirrel?
A different red mammal has ambled on Irish soil a lot longer than the squirrel; the red deer. McDevitt and a collaboration of scientists conducted a variety of studies on modern and ancient samples of red deer to determine if any of the deer currently residing in Ireland were descendants of ancient deer or recent introductions.
Samples going back 30,000 years were compared to deer currently residing at various locations around the country. Genetic analysis on the mitochondrial DNA showed that the deer in Killarney National Park shared the same haplotype, IRE2, as the very ancient Irish samples (about 30,000 years old). Haplotypes are specific areas along DNA that are close together so are passed down through generations. This is a good method to analyse populations of the same species.
DNA cannot recount the entire tale as the fossil record adds an unusal twist. McDevitt explains that “red deer are completely absent from Ireland from about 11,000 to 5,000 years ago. We think that this haplotype existed in Britain as well. It was in Ireland, died out and was restocked with the same haplotype”. This means that red deer, originally from Britain, lived in Ireland before the last ice age. Like all other deer species, they died out when the island froze and the same British species were re-introduced during the Irish Neolithic period. The re-introduction was most likely done intentionally by humans. This has still to be proven but new genetic analysis in the UK should shed light on this theory in the near future.
This type of research is not only important from a historical point of view but also in modern conservation. McDevitt terms this applied conservation. “We showed that the red deer in Killarney were the only population that have been here for the last 5,000 years so we think that they should be given full protection”. Genetic analysis is becoming increasingly important in conservation and may help determine the impact of re-introductions such as the recently released wild boar and invasive species such as the greater white-toothed shrew.
After speaking to McDevitt, my assumptions about “Irish” land mammals have been shattered. The research that is currently being carried out by these collaborations will make us re-evaluate our history and how we view and protect the animals we share this island with. The immigration office may be in for a few surprises!
Carden, R.F., et al. (2012). Phylogeographic, ancient DNA, fossil and morphometric analyses reveal ancient and modern introductions of a large mammal: the complex case of red deer (Cervus elaphus) in Ireland Quaternary Science Reviews DOI: 10.1016/j.quascirev.2012.02.012
About AIMS 2012:
The Second All Ireland Mammal Symposium (AIMS2012) which will be held on the 26th & 27th October 2012 an the National Botanic Gardens, Dublin, Ireland. The call for abstracts closes August 31st.
AIMS2012 follows on from the highly successful AIMS2009 and will promote awareness of the conservation status of mammals on the island of Ireland, the importance of mammalian biodiversity and the need to protect their habitats on the island, especially in the light of increased proliferation of invasive species.
The keynote addresses will be given by Prof. Xavier Lambin (University of Aberdeen) and Dr Simon Berrow (Irish Whale and Dolphin Group and Galway-Mayo Institute of Technology). For more information, click here.