Allele Surfing and Holocene Expansion of an Australian Fig (Ficus—Moraceae)

Brendan C Wilde,Maurizio Rossetto,Jia-Yee S Yap,Susan Rutherford

doi:10.3390/d13060250

Brendan C Wilde, Maurizio Rossetto + Show 2 more

Open Access

https://doi.org/10.3390/d13060250

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Journal: Diversity	Publication Date: Jun 7, 2021
Citations: 1	License type: CC BY 4.0

Affiliation: Royal Botanic Garden Sydney, Jiangsu University

Abstract

The creek sandpaper fig of southeastern Australia, Ficus coronata Spin, is culturally significant to Australian traditional owners who made use of the leaves to smooth timber and ate the fruit. The species is thought to have a long history on the continent, with some suggesting a Gondwanan origin. However, distributional patterns and overall ecology suggest a recent expansion across suitable habitats. We used landscape genomic techniques and environmental niche modelling to reconstruct its history and explore whether the species underwent a recent and rapid expansion along the east coast of New South Wales. Genomic analysis of 178 specimens collected from 32 populations throughout the species’ New South Wales distribution revealed a lack of genetic diversity and population structure. Some populations at the species’ southern and western range limits displayed unexpected diversity, which appears to be the result of allele surfing. Field work and genetic evidence suggest a Holocene expansion which may have increased since European colonisation. We also present a novel method for detecting allele surfing—MAHF (minor allele at highest frequency).

Highlights

IntroductionDuring the Pleistocene, the climate oscillated between glacial and interglacial periods, repeatedly forcing species to contract into refugia (or become extinct), expand as conditions improved [5,6]
This study has implications for conservation and management of this species, which is currently regarded as threatened in Victoria (Flora and Fauna Guarantee Act 1988—Threatened List November 2019)
Not sampled in this study, it appears likely the F. coronata has recently expanded into eastern Victoria, possibly in the last century

Summary

Introduction

During the Pleistocene, the climate oscillated between glacial and interglacial periods, repeatedly forcing species to contract into refugia (or become extinct), expand as conditions improved [5,6]. Periods of contraction condensed populations into isolated gene pools, while expansion enabled populations to grow and diverge in response to new environments [7,8] or admix on contact with new populations [9]. These contraction and expansion cycles formed the basis from which today’s species distribution and population structure developed [10]

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