DNA analysis of Castanea sativa (sweet chestnut) in Britain and Ireland: Elucidating European origins and genepool diversity

Abstract

Castanea sativa is classified as non-indigenous in Britain and Ireland. It was long held that it was first introduced into Britain by the Romans, until a recent study found no corroborative evidence of its growing here before c. AD 650. This paper presents new data on the genetic diversity of C. sativa in Britain and Ireland and potential ancestral sources in continental Europe. Microsatellite markers and analytical methods tested in previous European studies were used to genotype over 600 C. sativa trees and coppice stools, sampled from ancient semi-natural woodlands, secondary woodlands and historic cultural sites across Britain and Ireland. A single overall genepool with a diverse admixture of genotypes was found, containing two sub groups differentiating Wales from Ireland, with discrete geographical and typological clusters. C. sativa genotypes in Britain and Ireland were found to relate predominantly to some sites in Portugal, Spain, France, Italy and Romania, but not to Greece, Turkey or eastern parts of Europe. C. sativa has come to Britain and Ireland from these western European areas, which had acted as refugia in the Last Glacial Maximum; we compare its introduction with the colonization/translocation of oak, ash, beech and hazel into Britain and Ireland. Clones of C. sativa were identified in Britain, defining for the first time the antiquity of some ancient trees and coppice stools, evincing both natural regeneration and anthropogenic propagation over many centuries and informing the chronology of the species’ arrival in Britain. This new evidence on the origins and antiquity of British and Irish C. sativa trees enhances their conservation and economic significance, important in the context of increasing threats from environmental change, pests and pathogens.

Population genetics as a tool to elucidate pathogen reservoirs: Lessons fromPseudogymnoascus destructans, the causative agent of White‐Nose disease in bats

“…So far, population genetics have already been used to answer a broad range of questions related to pathogen biology (including parasitology). Examples of this include the elucidation of clonality in pathogens (e.g., Hill et al, 1995; Morehouse et al, 2003) and understanding the spatial structure and diversity of a pathogen in a geographical range (e.g., Anderson et al, 2000; Mekonnen et al, 2020) which can further be used to identify the source population of a pathogen's introduction (e.g., Jarman et al, 2019). These types of studies investigate patterns over long (evolutionary) time frames, which are an important part of the framework for understanding wildlife diseases (e.g., Vander Wal et al, 2014).…”

Population genetics as a tool to elucidate pathogen reservoirs: Lessons fromPseudogymnoascus destructans, the causative agent of white-nose disease in bats

“…Anderson et al, 2000; Mekonnen et al, 2020) which can further be used to identify the source population of a pathogen’s introduction (e.g. Jarman et al, 2019). These types of studies investigate patterns of large (evolutionary) time frames, which are a valid and important part of the framework to understanding wildlife diseases (e.g.…”

Single Nucleotide Polymorphisms as Practical Molecular Tools to Support European Chestnut Agrobiodiversity Management

“…In fact, it was reported that the information included in the analyses of a number of microsatellites ranging from 16 to 24 is enough for a robust estimation of distances among European chestnuts [ 23 , 41 , 42 ] and that, in allogamous species, the variability monitored by a microsatellite corresponds to the variability that can be monitored by seven to 11 SNPs [ 43 ]. In the more recent literature, the use of microsatellite molecular markers combined with agronomic and morphological observations was very useful for studying stress adaptation and the genetic origin of the European chestnut populations [ 20 , 21 , 42 , 44 ]. The provided widening of the available molecular tools will open up new horizons for these applications.…”

“…These markers are efficient, reliable and were widely used for population studies and cultivar genotyping. Recently, they have been used for characterizing Iberian and British populations and, combined with morphological observations, they allowed to come to important practical conclusions about natural populations’ biodiversity [ 20 , 21 ]. Nonetheless, they require a workflow that is not compatible with cost effective and easy-to-use applications as it includes a thorough DNA purification, amplification in presence of fluorescent-labeled primers, capillary electrophoresis, as well as complex data elaboration.…”