Quercus Conservation Genetics and Genomics: Past, Present, and Future

Janet R Backs,Mary V Ashley

doi:10.3390/f12070882

Abstract

Quercus species (oaks) have been an integral part of the landscape in the northern hemisphere for millions of years. Their ability to adapt and spread across different environments and their contributions to many ecosystem services is well documented. Human activity has placed many oak species in peril by eliminating or adversely modifying habitats through exploitative land usage and by practices that have exacerbated climate change. The goal of this review is to compile a list of oak species of conservation concern, evaluate the genetic data that is available for these species, and to highlight the gaps that exist. We compiled a list of 124 Oaks of Concern based on the Red List of Oaks 2020 and the Conservation Gap Analysis for Native U.S. Oaks and their evaluations of each species. Of these, 57% have been the subject of some genetic analysis, but for most threatened species (72%), the only genetic analysis was done as part of a phylogenetic study. While nearly half (49%) of published genetic studies involved population genetic analysis, only 16 species of concern (13%) have been the subject of these studies. This is a critical gap considering that analysis of intraspecific genetic variability and genetic structure are essential for designing conservation management strategies. We review the published population genetic studies to highlight their application to conservation. Finally, we discuss future directions in Quercus conservation genetics and genomics.

Highlights

Oaks have evolved and adapted over the past 56 million years [1]
While nearly half (49%) of published genetic studies involved population genetic analysis, only 16 species of concern (13%) have been the subject of these studies. This is a critical gap considering that analysis of intraspecific genetic variability and genetic structure are essential for designing conservation management strategies
We used citations in the Red List, the Gap Analysis, Google Scholar Searches, and citations contained within these studies, to identify genetic studies that have been conducted on the species on our list, with the caveat that the results represent a ‘point in time’ and that new research is constantly being added, may not yet be published, or was not found by this search protocol

Summary

Introduction

Oaks have evolved and adapted over the past 56 million years [1]. Their success has been attributed to high genetic diversity, rapid migration and adaptability, and their propensity for hybridization and introgression [2]. Species richness is especially high in North America and Asia, where oaks have adapted (and speciated) in response to varying ecological niches [2]. Some oaks, such as Q. hinckleyi, are as small as one meter at maturity and grow as clumps of long-lived clones. More familiar to most are large trees that dominate the landscape and live for hundreds of years, such as Quercus macrocarpa, Q. petraea and Q. robur They can be extremely rare and critically threatened (Q. hinckleyi [17,18]) or abundant with wide-spread distributions, like the other species just mentioned. These findings motivated our effort here to evaluate the state of Quercus conservation genetics

Developing a List of Oaks of Concern

Genetic Research on Oaks of Concern

Population Genetics for Oaks of Concern

Method Used

Findings

Future Directions