Genetic, morphological, and spectral characterization of relictual Niobrara River hybrid aspens (Populus × smithii)

Nicholas John Deacon, Jake Joseph Grossman, Anna Katharina Schweiger, Isabella Armour, Jeannine Cavender-Bares

Research output: Contribution to journalArticle

2 Citations (Scopus)

Abstract

PREMISE OF THE STUDY: Aspen groves along the Niobrara River in Nebraska have long been a biogeographic curiosity due to morphological differences from nearby remnant Populus tremuloides populations. Pleistocene hybridization between P. tremuloides and P. grandidentata has been proposed, but the nearest P. grandidentata populations are currently several hundred kilometers east. We tested the hybrid-origin hypothesis using genetic data and characterized putative hybrids phenotypically. METHODS: We compared nuclear microsatellite loci and chloroplast sequences of Niobrara River aspens to their putative parental species. Parental species and putative hybrids were also grown in a common garden for phenotypic comparison. On the common garden plants, we measured leaf morphological traits and leaf-level spectral reflectance profiles, from which chemical traits were derived. KEY RESULTS: The genetic composition of the three unique Niobrara aspen genotypes is consistent with the hybridization hypothesis and with maternal chloroplast inheritance from P. grandidentata. Leaf margin dentition and abaxial pubescence differentiated taxa, with the hybrids showing intermediate values. Spectral profiles allowed statistical separation of taxa in short-wave infrared wavelengths, with hybrids showing intermediate values, indicating that traits associated with internal structure of leaves and water absorption may vary among taxa. However, reflectance values in the visible region did not differentiate taxa, indicating that traits related to pigments are not differentiated. CONCLUSIONS: Both genetic and phenotypic results support the hypothesis of a hybrid origin for these genetically unique aspens. However, low genetic diversity and ongoing ecological and climatic threats to the hybrid taxon present a challenge for conservation of these relictual boreal communities.

Original languageEnglish (US)
Pages (from-to)1878-1890
Number of pages13
JournalAmerican journal of botany
Volume104
Issue number12
DOIs
StatePublished - Dec 2017

Fingerprint

Populus
Rivers
rivers
river
Populus grandidentata
Populus tremuloides
Chloroplasts
chloroplast
reflectance
garden
leaves
hybridization
chloroplasts
Radio Waves
Exploratory Behavior
Plant Leaves
Dentition
dentition
groves
spectral reflectance

Keywords

  • Clonal growth
  • Common garden
  • Hybridization
  • Nebraska
  • Niobrara river
  • Populus
  • Relictual communities
  • Salicaceae
  • Smith’s aspen
  • Spectra

Cite this

Genetic, morphological, and spectral characterization of relictual Niobrara River hybrid aspens (Populus × smithii). / Deacon, Nicholas John; Grossman, Jake Joseph; Schweiger, Anna Katharina; Armour, Isabella; Cavender-Bares, Jeannine.

In: American journal of botany, Vol. 104, No. 12, 12.2017, p. 1878-1890.

Research output: Contribution to journalArticle

@article{0e46ef8c3f9f4c7697fcd1cd9b6a239b,
title = "Genetic, morphological, and spectral characterization of relictual Niobrara River hybrid aspens (Populus × smithii)",
abstract = "PREMISE OF THE STUDY: Aspen groves along the Niobrara River in Nebraska have long been a biogeographic curiosity due to morphological differences from nearby remnant Populus tremuloides populations. Pleistocene hybridization between P. tremuloides and P. grandidentata has been proposed, but the nearest P. grandidentata populations are currently several hundred kilometers east. We tested the hybrid-origin hypothesis using genetic data and characterized putative hybrids phenotypically. METHODS: We compared nuclear microsatellite loci and chloroplast sequences of Niobrara River aspens to their putative parental species. Parental species and putative hybrids were also grown in a common garden for phenotypic comparison. On the common garden plants, we measured leaf morphological traits and leaf-level spectral reflectance profiles, from which chemical traits were derived. KEY RESULTS: The genetic composition of the three unique Niobrara aspen genotypes is consistent with the hybridization hypothesis and with maternal chloroplast inheritance from P. grandidentata. Leaf margin dentition and abaxial pubescence differentiated taxa, with the hybrids showing intermediate values. Spectral profiles allowed statistical separation of taxa in short-wave infrared wavelengths, with hybrids showing intermediate values, indicating that traits associated with internal structure of leaves and water absorption may vary among taxa. However, reflectance values in the visible region did not differentiate taxa, indicating that traits related to pigments are not differentiated. CONCLUSIONS: Both genetic and phenotypic results support the hypothesis of a hybrid origin for these genetically unique aspens. However, low genetic diversity and ongoing ecological and climatic threats to the hybrid taxon present a challenge for conservation of these relictual boreal communities.",
keywords = "Clonal growth, Common garden, Hybridization, Nebraska, Niobrara river, Populus, Relictual communities, Salicaceae, Smith’s aspen, Spectra",
author = "Deacon, {Nicholas John} and Grossman, {Jake Joseph} and Schweiger, {Anna Katharina} and Isabella Armour and Jeannine Cavender-Bares",
year = "2017",
month = "12",
doi = "10.3732/ajb.1700268",
language = "English (US)",
volume = "104",
pages = "1878--1890",
journal = "American Journal of Botany",
issn = "0002-9122",
publisher = "Botanical Society of America Inc.",
number = "12",

}

TY - JOUR

T1 - Genetic, morphological, and spectral characterization of relictual Niobrara River hybrid aspens (Populus × smithii)

AU - Deacon, Nicholas John

AU - Grossman, Jake Joseph

AU - Schweiger, Anna Katharina

AU - Armour, Isabella

AU - Cavender-Bares, Jeannine

PY - 2017/12

Y1 - 2017/12

N2 - PREMISE OF THE STUDY: Aspen groves along the Niobrara River in Nebraska have long been a biogeographic curiosity due to morphological differences from nearby remnant Populus tremuloides populations. Pleistocene hybridization between P. tremuloides and P. grandidentata has been proposed, but the nearest P. grandidentata populations are currently several hundred kilometers east. We tested the hybrid-origin hypothesis using genetic data and characterized putative hybrids phenotypically. METHODS: We compared nuclear microsatellite loci and chloroplast sequences of Niobrara River aspens to their putative parental species. Parental species and putative hybrids were also grown in a common garden for phenotypic comparison. On the common garden plants, we measured leaf morphological traits and leaf-level spectral reflectance profiles, from which chemical traits were derived. KEY RESULTS: The genetic composition of the three unique Niobrara aspen genotypes is consistent with the hybridization hypothesis and with maternal chloroplast inheritance from P. grandidentata. Leaf margin dentition and abaxial pubescence differentiated taxa, with the hybrids showing intermediate values. Spectral profiles allowed statistical separation of taxa in short-wave infrared wavelengths, with hybrids showing intermediate values, indicating that traits associated with internal structure of leaves and water absorption may vary among taxa. However, reflectance values in the visible region did not differentiate taxa, indicating that traits related to pigments are not differentiated. CONCLUSIONS: Both genetic and phenotypic results support the hypothesis of a hybrid origin for these genetically unique aspens. However, low genetic diversity and ongoing ecological and climatic threats to the hybrid taxon present a challenge for conservation of these relictual boreal communities.

AB - PREMISE OF THE STUDY: Aspen groves along the Niobrara River in Nebraska have long been a biogeographic curiosity due to morphological differences from nearby remnant Populus tremuloides populations. Pleistocene hybridization between P. tremuloides and P. grandidentata has been proposed, but the nearest P. grandidentata populations are currently several hundred kilometers east. We tested the hybrid-origin hypothesis using genetic data and characterized putative hybrids phenotypically. METHODS: We compared nuclear microsatellite loci and chloroplast sequences of Niobrara River aspens to their putative parental species. Parental species and putative hybrids were also grown in a common garden for phenotypic comparison. On the common garden plants, we measured leaf morphological traits and leaf-level spectral reflectance profiles, from which chemical traits were derived. KEY RESULTS: The genetic composition of the three unique Niobrara aspen genotypes is consistent with the hybridization hypothesis and with maternal chloroplast inheritance from P. grandidentata. Leaf margin dentition and abaxial pubescence differentiated taxa, with the hybrids showing intermediate values. Spectral profiles allowed statistical separation of taxa in short-wave infrared wavelengths, with hybrids showing intermediate values, indicating that traits associated with internal structure of leaves and water absorption may vary among taxa. However, reflectance values in the visible region did not differentiate taxa, indicating that traits related to pigments are not differentiated. CONCLUSIONS: Both genetic and phenotypic results support the hypothesis of a hybrid origin for these genetically unique aspens. However, low genetic diversity and ongoing ecological and climatic threats to the hybrid taxon present a challenge for conservation of these relictual boreal communities.

KW - Clonal growth

KW - Common garden

KW - Hybridization

KW - Nebraska

KW - Niobrara river

KW - Populus

KW - Relictual communities

KW - Salicaceae

KW - Smith’s aspen

KW - Spectra

UR - http://www.scopus.com/inward/record.url?scp=85038827628&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85038827628&partnerID=8YFLogxK

U2 - 10.3732/ajb.1700268

DO - 10.3732/ajb.1700268

M3 - Article

C2 - 29247028

AN - SCOPUS:85038827628

VL - 104

SP - 1878

EP - 1890

JO - American Journal of Botany

JF - American Journal of Botany

SN - 0002-9122

IS - 12

ER -