Fine-scale variation in soil properties promotes local taxonomic diversity of hybridizing oak species (Quercus spp.)
Data files
Jan 23, 2025 version files 534.32 KB
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2025_EVA_data.xlsx
412.68 KB
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2025_EVA_test_individuals.stru
78.48 KB
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2025_EVA_training_individuals.stru
40.95 KB
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README.md
2.21 KB
Abstract
Although many tree species frequently hybridize and backcross, management decisions in forestry and nature conservation are usually concentrated on pure species. Therefore, understanding which environmental factors drive the distribution and admixture of tree species on local stand scale is of great interest to support decision making in the establishment and management of resilient forests. We extensively sampled a mixed stand of hybridizing white oaks (Quercus petraea and Q. pubescens) near Lake Neuchâtel (Switzerland), where limestone and glacier moraine geologies coexist in proximity, to test whether micro-environmental conditions can predict taxonomic distribution and genetic admixture. We collected DNA from bud tissue, individual soil samples and extracted high-resolution topographic data for 385 oak trees. We used 50 species-discriminatory single nucleotide polymorphism (SNP) markers to determine the taxonomic composition and admixture levels of individual trees and tested their association with micro-environmental conditions. We show that the trees’ taxonomic distribution can be explained mainly by geographic position, soil pH and potential rooting depth, a proxy for soil water availability. We found that admixed individuals tend to grow in habitats being characteristic for the more drought-tolerant species Q. pubescens rather than in intermediate habitats. Using in-situ measurements, we are the first to show that fine-scale variation in soil properties related to pH and water availability potentially drives the distribution of hybridizing tree species in a mixed stand. Micro-environmental variation therefore promotes local taxonomic diversity, facilitates admixture and adaptive introgression, and contributes to the resilience of forests under environmental change. Consequently, species such as white oaks should be managed and protected as a species complex rather than as pure species.
README: Fine-scale variation in soil properties promotes local taxonomic diversity of hybridizing oak species (Quercus spp.)
https://doi.org/10.5061/dryad.n8pk0p35w
Description of the data and file structure
The dataset 2025_EVA_data.xlsx contains (consists of 8 spreadsheets) all environmental, topographic, and geographic variables and taxonomic data (STRUCTURE Q-values) for the 385 sampled trees. The datasets 2025_EVA_test_individuals.stru and 2025_EVA_training_individuals.stru contain the STRUCTURE input files resulting from the kompetitive allele specific PCR (KASP) genotyping for the 385 sampled trees and the training individuals, respectively. Please contact the corresponding author if there are any questions regarding the data.
Files and variables
File: 2025_EVA_data.xlsx
Variables
Some empty cell scan be found in the data file (because, e.g., soil measurements were not possible in the corresponding soil depth) and are not filled with "n/a" due to possible interference with the analysis scripts which can be found on the GitLab page linked at the bottom of this file.
- ID (Tree ID)
- Q_robur (STRUCTURE Q-values Quercus robur)
- Q_petraea (STRUCTURE Q-values Quercus petraea)
- Q_pubescens (STRUCTURE Q-values Quercus pubescens)
- lon (longitude; m East; Swiss LV95)
- lat (latitude; m North; Swiss LV95)
- alt (altitude; m above sealevel)
- slp (slope; degrees)
- asp (northness)
- tri (topographic ruggedness index)
- hoc (horizontal curvature; degrees per m)
- vec (vertical curvature; degrees per m)
- tpi (topographic positioning index)
- twi (topographic wetness index)
- mpi (morphometric protection index)
- ddg (downslope distance gradient; degrees)
- pti (potential total insolation; kWh per square m)
- prd (potential rooting depth; cm)
- lid (lime depth; cm)
- tph (topsoil pH)
- sph (deep soil pH)
- DBH (diameter at breast height; cm)
Access information
Other publicly accessible locations of the data and analysis scripts:
https://gitlabext.wsl.ch/felix.zimmermann/2025_eva_quercus_taxonomic_diversity