DOI: 10.5061/dryad.931zcrjtk
title: Data from: What shapes the genetic diversity of the <em>Alnus cordata</em> species across its Italian native range? informing conservation strategies

description: Aim: Alnus cordata is an endemic tree species native to the Southern
 Italian Apennines and north-eastern Corsica, renowned for its ecological
 significance. Climate change projections for the Mediterranean basin
 indicate range shifts and increased fragmentation for many forest trees
 including A. cordata. Hybridization with the sympatric A. glutinosa in the
 central part of its Italian native range may also influence the genetic
 structure and conservation priorities for A. cordata. A comprehensive
 conservation strategy is needed to preserve its genetic resources in
 Italy. Method: We analyzed the genetic diversity, population structure,
 and extent of hybridization with A. glutinosa in 23 A. cordata forest
 stands across its native Italian range using nuclear microsatellites.
 Habitat suitability was modeled under current and future climate scenarios
 using an ensemble forecasting approach. Conservation prioritization was
 guided by a genetically informed Reserve Selection analysis in DIVA-GIS to
 identify areas of high conservation value and address gaps in genetic
 resource representation. Results: Italian alder populations exhibit low
 genetic diversity, which decreases towards the southern latitudinal
 margins of the peninsula. Hybridization and introgression with Alnus
 glutinosa have a geographically localized impact on the genetic variation
 within A. cordata populations. Local increases in private allelic richness
 do not alter the spatial genetic structure of A. cordata, but they help
 mitigate the risk of severe genetic erosion. A significant proportion of
 the species’ genetic diversity is effectively preserved through in situ
 conservation. Model projections under future climate scenarios indicate a
 substantial decline in habitat suitability for A. cordata stands with high
 priority for in situ conservation. This highlights the need for
 complementary strategies, including ex situ conservation measures.
 Conclusions: Our study highlights the importance of integrating genetic
 analyses, habitat suitability modeling, and spatial prioritization
 techniques for effective conservation planning of A. cordata in the face
 of climate change across the Mediterranean.
description: # **Data from: What shapes the genetic diversity of the Alnus cordata
 species across its Italian native range? informing conservation
 strategies**
 [https://doi.org/10.5061/dryad.931zcrjtk](https://doi.org/10.5061/dryad.931zcrjtk) ## Description of the data and file structure File excel "`SSRdata_AlderPopulations`" includes the raw data for genotyping 417 Italian alder (A. cordata) trees using 10 nSSR markers. File excel "`geographic sites Alnus`" includes: Geographic and sampling information of 25 alder populations. population code (Popcode), geographic coordinates in decimal degrees, latitude (Latitude) and longitude (Longitude), and elevation above sea level (Elevation) File excel "`SSRdata_AlderPopulations_glt_hyb`" includes the raw data for genotyping 96 European alder trees (A. glutinosa) and five hybrids using 10 nSSR markers File csv "`SpeciesOccurencesPoints_Filtered`" includes species occurrence points of A. cordata collected from native and non-native ranges of Italy and Corsica using (a) the Global Biodiversity Information Facility database [GBIF.org (6 November 2024) GBIF Occurrence Download [https://doi.org/10.15468/dl.nazq94](https://doi.org/10.15468/dl.nazq94)], (b) the EU-Forest dataset (Mauri et al. 2017), and through two fields surveys performed in 2012 and 2022 across Southern Italy. Besides our own 417 locations, another 2533 records were gathered for a total of 2949 data points. Duplicated records falling into the same pixel of the environmental variables and points occurring in the sea were excluded. As a result, the number of georeferenced records was reduced to 1877. The Geographic and sampling information of seven admixed alder populations (cord/glut), two pure populations of *A. glutinosa* (glut) and 16 pure populations of *A. cordata* (cord)are reported below: code (PopID), Population site (Pop_name), region (Region), geographic coordinates in decimal degrees, latitude (Lat.) and longitude (Long.), elevation (m) above sea level (Elev.) and location within National or Regional Park (Description) in Southern Italy. | Species | PopID | Pop\_name | Region | Description | | --------- | ----- | ----------------- | ---------- | ----------------------------------------------------- | | cord | AVE | Avella | Campania | Regional Park of Partenio | | cord | MOF | Monte Faito | Campania | Regional Park of Lattari Mountains | | cord | BAI | Bagnoli Irpino | Campania | Regional Park of Picentini Mountains | | cord | LAU | Laurino | Campania | National Park of Cilento – Vallo di Diano | | cord/glut | SME | San Menale | Campania | National Park of Cilento – Vallo di Diano | | cord | CAV | Cavallara | Campania | National Park of Cilento – Vallo di Diano | | cord | CHI | Chiaie | Campania | National Park of Cilento – Vallo di Diano | | cord | RAC | Torrente Nocito | Basilicata | National Park Appennino Lucano Val d’Agri Lagonegrese | | cord | MAG | Torrente Maglie | Basilicata | National Park Appennino Lucano Val d’Agri Lagonegrese | | cord/glut | SAS | Sasso di Castalda | Basilicata | National Park Appennino Lucano Val d’Agri Lagonegrese | | cord/glut | ANZ | Anzi | Basilicata | National Park Appennino Lucano Val d’Agri Lagonegrese | | cord/glut | SEV | San Severino | Basilicata | National Park of Pollino | | cord | NUP | Nuppolara | Calabria | National Park of Pollino | | cord/glut | BUO | Buonvicino | Calabria | National Park of Pollino | | cord/glut | VIT | Vitimoso | Calabria | National Park of Pollino | | cord | ORS | Orsomarso | Calabria | National Park of Pollino | | cord | SCA | Scaragiani | Calabria | National Park of Pollino | | cord | CET | Cetraro | Calabria | Paolano Appennines-Cetraro | | cord | FIU | Fiumefreddo | Calabria | Paolano Appennines-Mendicino | | cord | MAC | Macrocioli | Calabria | National Park of Sila | | glut | CAM | Santa Severina | Calabria | Neto Valley | | cord | FOR | Forgevecchie | Calabria | RPSerre | | cord/glut | STA | Stafferino | Calabria | RPSerre | | cord | SBR | San Bruno | Calabria | National Park of Aspromonte | | glut | POD | San Bruno | Calabria | National Park of Aspromonte |