The demographic history of Castanea sativa Mill. in southwest Europe: A natural population structure modified by translocations

Abstract

In domesticated species, translocation of materials can alter natural demographic patterns; this may have occurred in Castanea sativa (European chestnut), a species conserved in several refuges, with a long domestication history for nut production. Bayesian analysis of population genetic structure in marginal areas and in the centre of C. sativa range, considering spatial information and making corrections for unbalanced size, allowed visualization of a genetic structure that was subsequently analysed by approximate Bayesian computation to assess its natural demographic history and test the origin of some hypothetical translocated germplasm. We obtained evidence of C. sativa population contraction during the earliest Pleistocene, resulting in a split into eastern (Greek) and western (Italian and Iberian) populations. The northern Iberian population, in the Eurosiberian area, is one of the vestiges that remained after the contraction that split the global Tertiary population. A secondary encounter, occurred from Middle to Upper Pleistocene, which explains the hybrid origin of the Western Mediterranean population present in Italy and in the centre and south of the Iberian Peninsula. It has been demonstrated that a germplasm translocation from Italy to the Central Iberian Range may have occurred. Recent translocations have hybridized with the local northern Iberian population, producing naturalized populations with high diversity. The populations of C. sativa in southwestern Europe have a genetic structure compatible with a natural origin, in which signs of population contractions and expansions caused by climatic oscillations since the Late Miocene have been imprinted.

Biodiversity protection against anthropogenic climate change: Conservation prioritization of Castanea sativa in the South Caucasus based on genetic and ecological metrics

“…The species was extensively cultivated in southern Europe for nuts and timber since the Roman Empire (Fernández‐López et al, 2021; Krebs et al, 2019; Marinoni et al, 2013; Mattioni et al, 2017). Recent studies revealed significant translocation of germplasm between the Iberian and Apennine peninsulas (Fernández‐López et al, 2021) and a considerable gene flow between cultivated orchards and natural populations in the Adriatic region (Tumpa et al, 2022). However, sweet chestnut is also found isolated in the Caucasus ecoregion, a global biodiversity hotspot (Tarkhnishvili et al, 2012; Zazanashvili et al, 2004).…”

“…(sweet chestnut), a relict Neogene tree species with a long history of domestication around the Mediterranean Basin. The species was extensively cultivated in southern Europe for nuts and timber since the Roman Empire (Fernández‐López et al, 2021; Krebs et al, 2019; Marinoni et al, 2013; Mattioni et al, 2017). Recent studies revealed significant translocation of germplasm between the Iberian and Apennine peninsulas (Fernández‐López et al, 2021) and a considerable gene flow between cultivated orchards and natural populations in the Adriatic region (Tumpa et al, 2022).…”

Evaluation of Chestnut Susceptibility to Cryphonectria parasitica: Screening under Controlled Conditions

“…It should be noted that 70% of the C. sativa genotypes and the 40% of progenies from Montseny inoculated with C. parasitica showed a response analogous to the one of C. mollissima in their canker development. These results are relevant because the chestnut orchards in Montseny are not described as having been introgressed with Asian materials as in other Spanish areas [35]. Their ancestry and traditional management in the last 100 years do not indicate the entry of foreign fruit varieties.…”

Heat stress and recovery effects on the physiology and biochemistry of Castanea sativa Mill.

“…Chestnut (Castanea sativa Mill.) is a temperate thermophilic tree distributed throughout the Mediterranean basin in natural, semi-natural, and managed stands of considerable environmental, cultural, and economic value (Fernández-López and Alía, 2003;Conedera et al, 2004;Fernández-López et al, 2021). Its main area of distribution in 10.…”

“…Its main area of distribution in 10. 3389/ffgc.2022.1072661 Spain is in the humid northwest region, as well as scattered stands in central and southern Iberia, where high temperatures are frequent (Fernández-López et al, 2021). Chestnut forests in Spain are threatened by global warming (e.g., May and July air temperatures hit a record high in 2022), providing an ideal testbed for studying heat stress effects.…”