Genomic variation patterns of subspecies defined by phenotypic criteria: analyses of the mangrove species complex, Avicennia marina

Wang, Zheng-Zhen, Guo, Zi-Xiao, Zhong, Cai-Rong, Lyu, Hao-Min, Li, Xin-Nian, Duke, Norman C., and Shi, Su-Hua (2022) Genomic variation patterns of subspecies defined by phenotypic criteria: analyses of the mangrove species complex, Avicennia marina. Journal of Systematics and Evolution. (In Press)

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Abstract

Subspecies is used to designate taxa below species but above geographical populations. What patterns of genomic variation are expected if taxa are designated as subspecies? In this study, we carry out such a survey on the mangrove tree Avicennia marina (Forssk.) Vierh. of the Indo-West Pacific coasts. This species has three subspecies, distinguished by morphological traits and geographical distribution. We collected samples from 16 populations (577 individuals) covering all three subspecies and sequenced 94 nuclear genes. We reveal comprehensive genetic divergence among subspecies, generally higher than among geographical populations within subspecies. The level of genetic diversity differs among the three subspecies, possibly hinting at a degree of separation among their gene pools. We observed that divergence varies from locus to locus across the genome. A small portion of the genome is most informative about subspecies delineation, whereas the rest is undifferentiated or slightly differentiated, hinting at uneven gene flow and incomplete isolation. The three subspecies likely split simultaneously with gene flow among lineages. This reticulate evolution results in some discordance between morphology and genetics in areas of population contact. In short, A. marina subspecies show species-like patterns in some respects and population-like patterns in others. We propose that the subspecies designated in A. marina are informative in predicting genetic divergences and useful in making conservation decisions.

Item ID: 72182
Item Type: Article (Research - C1)
ISSN: 1759-6831
Keywords: Avicennia marina, gene flow, mangrove, population genetics, speciation, subspecies
Copyright Information: © 2020 Institute of Botany, Chinese Academy of Sciences.
Date Deposited: 09 Feb 2022 10:24
FoR Codes: 31 BIOLOGICAL SCIENCES > 3104 Evolutionary biology > 310411 Plant and fungus systematics and taxonomy @ 50%
31 BIOLOGICAL SCIENCES > 3104 Evolutionary biology > 310412 Speciation and extinction @ 50%
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