Corylus Avellana) in Ireland Brown, James; Beatty, Gemma; Montgomery, Ian; Provan, James
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Aberystwyth University Broad-scale genetic homogeneity in natural populations of common hazel (Corylus avellana) in Ireland Brown, James; Beatty, Gemma; Montgomery, Ian; Provan, James Published in: Tree Genetics and Genomes DOI: 10.1007/s11295-016-1079-7 Publication date: 2016 Citation for published version (APA): Brown, J., Beatty, G., Montgomery, I., & Provan, J. (2016). Broad-scale genetic homogeneity in natural populations of common hazel (Corylus avellana) in Ireland. Tree Genetics and Genomes, 12, [122]. https://doi.org/10.1007/s11295-016-1079-7 Document License CC BY General rights Copyright and moral rights for the publications made accessible in the Aberystwyth Research Portal (the Institutional Repository) are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights. • Users may download and print one copy of any publication from the Aberystwyth Research Portal for the purpose of private study or research. • You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the Aberystwyth Research Portal Take down policy If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim. tel: +44 1970 62 2400 email: [email protected] Download date: 03. Oct. 2019 Tree Genetics & Genomes (2016) 12:122 DOI 10.1007/s11295-016-1079-7 ORIGINAL ARTICLE Broad-scale genetic homogeneity in natural populations of common hazel (Corylus avellana) in Ireland James A. Brown1 & Gemma E. Beatty2 & W. Ian Montgomery1,3 & Jim Provan2 Received: 26 September 2016 /Revised: 1 November 2016 /Accepted: 10 November 2016 # The Author(s) 2016. This article is published with open access at Springerlink.com Abstract Hazel (Corylus avellana) has been a key species in Keywords Corylus avellana . Gene flow . Genetic diversity . European woodlands throughout the Holocene (10 KYA– Hazel . Hazelnut . Microsatellites . Spatial autocorrelation . present). Like many tree species, it is increasingly under threat Woodland management from climate change, habitat loss and fragmentation, invasive species and emergent pathogens. As knowledge of the genetic structure of natural populations of trees is vital for managing Introduction these threats, as well as an essential basis for selection of material for replanting and restocking, we analysed levels Hazel, Corylus avellana, has historically been a major com- and patterns of genetic diversity in the species at a range of ponent of woodlands across Europe and especially so in Great spatial scales using high-resolution microsatellite markers. Britain and Ireland. Pollen records suggest that hazel was one Our findings indicate that hazel populations exhibit high of the first species to re-colonize Europe after the last ice age levels of genetic diversity along with low levels of population (Huntley and Birks 1983; Huntley 1993), and the species’ differentiation, suggesting extensive gene flow. Fine-scale ge- present-day natural geographic distribution is extensive, rang- netic structuring was observed in some of the woodlands stud- ing from southern Norway and Finland to the north, the Ural ied, probably resulting from restricted dispersal of the heavy mountains of Russia to the east, northern Iberia to the west and nuts produced by the species. This, coupled with higher levels Morocco to the south. In Britain and Ireland, it is thought to of pollen-mediated gene flow, resulted in a weak but signifi- have replaced the early-colonizer Betula (birch), before being cant pattern of isolation by distance. These results suggest that relegated largely to an understory component by the arrival of replanting following potential loss of hazel populations may the three principal tree taxa of Pinus (pine), Quercus (oak) and not necessarily require the use of material from the same lo- Ulmus (elm; Huntley and Birks 1983; Mitchell 2006). cality and mirror findings in other broadleaved tree species Chloroplast DNA variation in the sole phylogeographic study from the same area. on wild hazels (Palme and Vendramin 2002) revealed genetic uniformity across the recolonized part of the species’ range, and it was hypothesised, taking into account the palynological data, that recolonization took place from a southwestern refu- Communicated by Z. Kaya gium and that populations in other refugia in Italy and the * Jim Provan Balkans remained in situ and did not spread outside these [email protected] areas. Hazel is a small, deciduous shrub that grows mainly not 1 School of Biological Sciences, Queen’s University Belfast, 97 only in forests but also in hedgerows. It is wind pollinated and Lisburn Road, Belfast BT9 7BL, UK monoecious but has mechanisms to prevent selfing, including 2 Institute of Biological, Environmental and Rural Sciences (IBERS), dichogamy and sporophytic incompatibility (Thompson Aberystwyth University, Penglais, Aberystwyth SY23 3DA, UK 1979). Its morphology is highly polymorphic, with the previ- 3 Institute for Global Food Security, Queen’s University Belfast, ously described species Corylus maxima, Corylus pontica and Belfast, UK Corylus colchica now being included as members of 122 Page 2 of 15 Tree Genetics & Genomes (2016) 12:122 C. avellana (Molnar 2011). Hazel trees produce nuts, which key native woodland species. We also investigate fine-scale are eaten by a range of animals, including birds such as jays genetic structuring, since it is envisaged that the large seeds of and nuthatches, and squirrels, dormice and other rodents hazel may have limited capacity for dispersal, even within (Howe and Smallwood 1982). It also acts as a host for the rare individual woodlands (Howe and Smallwood 1982). fungus Hypocreopsis rhododendri whose abundance has de- clined in Britain due to habitat clearance and consequently is included on the IUCN red list as being Bnear threatened^ Materials and methods (reviewed in Grundy et al. 2012). Genetic, historical and ar- chaeological data suggest that hazel was independently do- Sampling and DNA extraction mesticated in the Mediterranean (Spain and Italy) and in the Black Sea countries, and to date, over 400 cultivars have been Samples were collected from 25 sites across Northern Ireland described (Molnar 2011). There is evidence that hazelnuts along with four sites in the Republic of Ireland (Fig. 1; were a food source for early people, and thus, hazel may have Table 1). The samples were taken from a combination of been planted or accidentally spread by human migration, po- hedgerows and woodland, depending on the site, but mainly tentially increasing its range and abundance beyond that the latter. Woodlands were selected that had been designated which resulted from natural seed dispersal alone (reviewed as ancient or semi-natural, based on the data collected for the in Boccacci and Botta 2009). Woodland Trust Inventory of ancient and long-established Like many woodland species, hazel has come under threat woodland in Northern Ireland (www.backonthemap.org.uk) fromanumberofemergentdiseasesinrecentyears,aswellas and the National Survey of Native Woodlands 2003–2008 in being threatened by the same factors which affect native the Republic of Ireland (www.npws.ie). Woodlands were also woodlands in general such as climate change, land use selected based on government information from the change, habitat loss, invasive species and pests (Rackham Department of the Environment such as Areas of Special 2008). It is currently at risk from Eastern Filbert Blight Scientific Interest (ASSIs), as well as the landscape character (Anisogramma anomala), a canker disease that is fatal in areas listing the woodlands and species present in each region C. avellana. The fungal pathogen spreads through ascospores, (https://www.doeni.gov.uk). A set of samples were also taken which are discharged from infected branches from autumn to from the natural vegetation surrounding the botanical garden late spring and are spread by rainwater. It can take up to at Sospirolo, Italy. For sampling, a number of leaves were 15 years for a mature infected tree to die, but during that time, taken from each of a maximum of 30 trees and stored in the tree retains the potential to release ascospores, which will silica gel. The GPS coordinates of each tree were recorded. infect other trees (Johnson et al. 1996). In the UK, the disease DNA was extracted using the cetyltrimethylammonium has been classified by the Department for Environment, Food bromide (CTAB) method (Doyle and Doyle 1987). and Rural Affairs (DEFRA) as 3/5 in terms of likelihood of entry, 5/5 in terms of likelihood of establishment and 5/5 in Genotyping terms of impact (DEFRA 2014). Among other potential threats, in Greece and Italy, the bacterium Pseudomonas All samples were genotyped for seven nuclear avellanae, which causes bacterial canker and decline of hazel- microsatellites (A604, A605, A613, A614, B671, B767, nut, has resulted in the destruction of cultivated hazel trees, B791), which had previously been developed for use in and to date, more than 40,000 trees have been lost (Scortichini European hazelnut (Gürcan et al. 2010a). PCR was carried et al. 2002). out in a total volume of 10 μl containing 100 ng genomic Knowledge of the genetic structure of natural populations DNA,5pmolof6-FAM-labelledM13primer,0.05pmol of trees