DOI: 10.5061/dryad.v9s4mw789
title: Microsatellite Genotype data of <em>Populus fremontii</em> and <em>Populus angustifolia</em>

description: Interspecific hybridization in forest trees is common and can have
 important implications for ecology, evolution, and the conservation of
 forest habitats. Hybridization often results in greater genetic diversity
 and opportunities for backcrossing with one or both parents, which may
 introduce novel genotypes that influence biodiversity and ecosystem
 processes. However, the extent of hybridization, direction of
 backcrossing, and overall survival and performance of hybrids is often
 poorly understood, leading to inaccurate assessments of the role hybrids
 may play in forest ecology and conservation. Here, we investigate
 interspecific hybridization and the extent and direction of backcrossing
 between two species, Populus fremontii (S. Watson) and P. angustifolia (E.
 James ex Torr.), which are broadly distributed along riparian corridors in
 the riparian ecosystems of the southwestern United States. Using molecular
 assays of six putative hybrid zones and a common garden trial we test the
 following: (1) whether putative hybrids show evidence of genetic
 intermediacy relative to the parent species; (2) if confirmed hybrids
 exhibit higher genetic diversity than either parent species; (3) the
 extent and direction of backcrossing (uni- or bi-directional) within each
 site; and (4) whether hybrid derivatives show evidence of higher survival
 and performance in an experimental common garden consisting of both
 parents and hybrids that were propagated from the six sites. Our results
 confirm genetic intermediacy in all six sites, but with varying degrees of
 backcrossing, genetic diversity, and structure. All six locations reveal
 extensive bidirectional backcrossing to both parent species, a result that
 contrasts with previous findings, which suggest that backcrossing is
 predominantly unidirectional between the two species. Results from our
 common garden trial indicate that hybrids do not have higher survival or
 out-perform the parent species, suggesting that heterosis may be limited
 in this system, or that long-term assessments beyond the duration of our
 field experiment may be required. Results from this study improve our
 understanding of the frequency of hybridization, and the associated
 backcrossing in this system, and provide land managers with information on
 how hybrids may be employed for the long-term preservation of riparian
 habitats undergoing rapid environmental change. This is a dataset of
 diploid microsatellite genotypes for 163 samples from the genus Populus,
 using 10 microsatellite loci. Genotypes are reported as fragment lengths
 in basepairs, and are reported in biallelic format (i.e., two columns per
 loci).
description: # Microsatellite Genotype data of *Populus fremontii* and *Populus
 angustifolia* Dataset DOI:
 [10.5061/dryad.v9s4mw789](10.5061/dryad.v9s4mw789) ## Description of the
 data and file structure This is a dataset of diploid microsatellite
 genotypes for 163 samples from the genus *Populus,* using 10
 microsatellite loci. Genotypes are reported as fragment lengths in
 basepairs, and are reported in biallelic format (i.e., two columns per
 loci). The document is formatted as a .csv, with sample names listed in
 the first column ("Sample"), cross-type is labeled in the second
 column ("Pop"), and the source location is listed in the third
 column ("Site"), and loci names listed on the top row (with two
 names, [locus]_1 and [locus]_2, to account for two columns per locus).
 Missing data is coded as "0". Information on how the samples
 were collected and processed can be found in Scull et al. 2025 -
 "Interspecific Hybridization in *Populus* L., and Its Implications
 for the Ecology and Management of Riparian Ecosystems in the Southwestern
 USA" published in MDPI Forests.  ### Files and variables #### File:
 Populus_Genotype_Data_Sculletal2025.csv **Description:**  ##### Variables
 * Sample: Sample ID. Acronym is based on a two-letter abbreviation of the
 sample site (e.g. "BR"), a one-letter abbreviation of the
 cross-type (e.g. "F"), and a number identifying the replicate
 (1, 2, 3, etc).  * Pop: The cross-type of the sample, as identified by
 structure analysis of the samples. F1 = F1 hybrid, N = narrowleaf, F =
 Fremont, BCF = backcross to Fremont, BCN = backcross to narrowleaf.  *
 Site: The name of the river system from which the data was sourced.  *
 GCPM... etc.: Locus name. Each locus has two columns, [locus]_1 and
 [locus2], to account for diploid genotypes.  ## Code/software This is a
 .csv that can be opened in any plain-text editor or Microsoft Excel. Data
 is formatted for use by the program STRUCTURE and any software that can
 utilize bi-allelic STRUCTURE files.  ## Access information Other publicly
 accessible locations of the data: * None Data was derived from the
 following sources: * Data was generated using .ab1 fragment analysis files
 generated on the ABI 3730. Raw fragment traces were scored manually using
 the program GeneMarker.