Conserving threatened riparian ecosystems in the American West: Precipitation gradients and river networks drive genetic connectivity and diversity in a foundation riparian tree (Populus angustifolia)

Helen M. Bothwell, Samuel A. Cushman, Scott A. Woolbright, Erika I. Hersch-Green, Luke M. Evans, Thomas G Whitham, Gerard J Allan

Research output: Contribution to journalArticle

9 Citations (Scopus)

Abstract

Gene flow is an evolutionary process that supports genetic connectivity and contributes to the capacity of species to adapt to environmental change. Yet, for most species, little is known about the specific environmental factors that influence genetic connectivity, or their effects on genetic diversity and differentiation. We used a landscape genetic approach to understand how geography and climate influence genetic connectivity in a foundation riparian tree (Populus angustifolia), and their relationships with specieswide patterns of genetic diversity and differentiation. Using multivariate restricted optimization in a reciprocal causal modelling framework, we quantified the relative contributions of riparian network connectivity, terrestrial upland resistance and climate gradients on genetic connectivity. We found that (i) all riparian corridors, regardless of river order, equally facilitated connectivity, while terrestrial uplands provided 2.5× more resistance to gene flow than riparian corridors. (ii) Cumulative differences in precipitation seasonality and precipitation of the warmest quarter were the primary climatic factors driving genetic differentiation; furthermore, maximum climate resistance was 45× greater than riparian resistance. (iii) Genetic diversity was positively correlated with connectivity (R2 = 0.3744, p = .0019), illustrating the utility of resistance models for identifying landscape conditions that can support a species' ability to adapt to environmental change. From these results, we present a map highlighting key genetic connectivity corridors across P. angustifolia's range that if disrupted could have long-term ecological and evolutionary consequences. Our findings provide recommendations for conservation and restoration management of threatened riparian ecosystems throughout the western USA and the high biodiversity they support.

Original languageEnglish (US)
JournalMolecular Ecology
DOIs
StateAccepted/In press - 2017

Fingerprint

Populus angustifolia
Populus
Climate
Rivers
Ecosystem
connectivity
Gene Flow
genetic variation
rivers
ecosystems
ecosystem
Genetic Phenomena
river
Geography
Biodiversity
riparian areas
genetic differentiation
climate
gene flow
highlands

Keywords

  • Climate gradients
  • Gene flow
  • Genetic and functional connectivity
  • Landscape genetics
  • Landscape resistance
  • Reciprocal causal modelling

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Genetics

Cite this

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title = "Conserving threatened riparian ecosystems in the American West: Precipitation gradients and river networks drive genetic connectivity and diversity in a foundation riparian tree (Populus angustifolia)",
abstract = "Gene flow is an evolutionary process that supports genetic connectivity and contributes to the capacity of species to adapt to environmental change. Yet, for most species, little is known about the specific environmental factors that influence genetic connectivity, or their effects on genetic diversity and differentiation. We used a landscape genetic approach to understand how geography and climate influence genetic connectivity in a foundation riparian tree (Populus angustifolia), and their relationships with specieswide patterns of genetic diversity and differentiation. Using multivariate restricted optimization in a reciprocal causal modelling framework, we quantified the relative contributions of riparian network connectivity, terrestrial upland resistance and climate gradients on genetic connectivity. We found that (i) all riparian corridors, regardless of river order, equally facilitated connectivity, while terrestrial uplands provided 2.5× more resistance to gene flow than riparian corridors. (ii) Cumulative differences in precipitation seasonality and precipitation of the warmest quarter were the primary climatic factors driving genetic differentiation; furthermore, maximum climate resistance was 45× greater than riparian resistance. (iii) Genetic diversity was positively correlated with connectivity (R2 = 0.3744, p = .0019), illustrating the utility of resistance models for identifying landscape conditions that can support a species' ability to adapt to environmental change. From these results, we present a map highlighting key genetic connectivity corridors across P. angustifolia's range that if disrupted could have long-term ecological and evolutionary consequences. Our findings provide recommendations for conservation and restoration management of threatened riparian ecosystems throughout the western USA and the high biodiversity they support.",
keywords = "Climate gradients, Gene flow, Genetic and functional connectivity, Landscape genetics, Landscape resistance, Reciprocal causal modelling",
author = "Bothwell, {Helen M.} and Cushman, {Samuel A.} and Woolbright, {Scott A.} and Hersch-Green, {Erika I.} and Evans, {Luke M.} and Whitham, {Thomas G} and Allan, {Gerard J}",
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T2 - Precipitation gradients and river networks drive genetic connectivity and diversity in a foundation riparian tree (Populus angustifolia)

AU - Bothwell, Helen M.

AU - Cushman, Samuel A.

AU - Woolbright, Scott A.

AU - Hersch-Green, Erika I.

AU - Evans, Luke M.

AU - Whitham, Thomas G

AU - Allan, Gerard J

PY - 2017

Y1 - 2017

N2 - Gene flow is an evolutionary process that supports genetic connectivity and contributes to the capacity of species to adapt to environmental change. Yet, for most species, little is known about the specific environmental factors that influence genetic connectivity, or their effects on genetic diversity and differentiation. We used a landscape genetic approach to understand how geography and climate influence genetic connectivity in a foundation riparian tree (Populus angustifolia), and their relationships with specieswide patterns of genetic diversity and differentiation. Using multivariate restricted optimization in a reciprocal causal modelling framework, we quantified the relative contributions of riparian network connectivity, terrestrial upland resistance and climate gradients on genetic connectivity. We found that (i) all riparian corridors, regardless of river order, equally facilitated connectivity, while terrestrial uplands provided 2.5× more resistance to gene flow than riparian corridors. (ii) Cumulative differences in precipitation seasonality and precipitation of the warmest quarter were the primary climatic factors driving genetic differentiation; furthermore, maximum climate resistance was 45× greater than riparian resistance. (iii) Genetic diversity was positively correlated with connectivity (R2 = 0.3744, p = .0019), illustrating the utility of resistance models for identifying landscape conditions that can support a species' ability to adapt to environmental change. From these results, we present a map highlighting key genetic connectivity corridors across P. angustifolia's range that if disrupted could have long-term ecological and evolutionary consequences. Our findings provide recommendations for conservation and restoration management of threatened riparian ecosystems throughout the western USA and the high biodiversity they support.

AB - Gene flow is an evolutionary process that supports genetic connectivity and contributes to the capacity of species to adapt to environmental change. Yet, for most species, little is known about the specific environmental factors that influence genetic connectivity, or their effects on genetic diversity and differentiation. We used a landscape genetic approach to understand how geography and climate influence genetic connectivity in a foundation riparian tree (Populus angustifolia), and their relationships with specieswide patterns of genetic diversity and differentiation. Using multivariate restricted optimization in a reciprocal causal modelling framework, we quantified the relative contributions of riparian network connectivity, terrestrial upland resistance and climate gradients on genetic connectivity. We found that (i) all riparian corridors, regardless of river order, equally facilitated connectivity, while terrestrial uplands provided 2.5× more resistance to gene flow than riparian corridors. (ii) Cumulative differences in precipitation seasonality and precipitation of the warmest quarter were the primary climatic factors driving genetic differentiation; furthermore, maximum climate resistance was 45× greater than riparian resistance. (iii) Genetic diversity was positively correlated with connectivity (R2 = 0.3744, p = .0019), illustrating the utility of resistance models for identifying landscape conditions that can support a species' ability to adapt to environmental change. From these results, we present a map highlighting key genetic connectivity corridors across P. angustifolia's range that if disrupted could have long-term ecological and evolutionary consequences. Our findings provide recommendations for conservation and restoration management of threatened riparian ecosystems throughout the western USA and the high biodiversity they support.

KW - Climate gradients

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KW - Landscape resistance

KW - Reciprocal causal modelling

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