Genetic patterns in Neotropical Magnolias (Magnoliaceae) using de novo developed microsatellite markers

Emily Veltjen,Alejandro Palmarola Bejerano,Luis Roberto González Torres,Ernesto Testé Lozano,Marie-Stéphanie Samain,Paul Goetghebeur,Majela Hernández Rodríguez,Isabel Larridon,Pieter Asselman

doi:10.1038/s41437-018-0151-5

Abstract

Conserving tree populations safeguards forests since they represent key elements of the ecosystem. The genetic characteristics underlying the evolutionary success of the tree growth form: high genetic diversity, extensive gene flow and strong species integrity, contribute to their survival in terms of adaptability. However, different biological and landscape contexts challenge these characteristics. This study employs 63 de novo developed microsatellite or SSR (Single Sequence Repeat) markers in different datasets of nine Neotropical Magnolia species. The genetic patterns of these protogynous, insect-pollinated tree species occurring in fragmented, highly-disturbed landscapes were investigated. Datasets containing a total of 340 individuals were tested for their genetic structure and degree of inbreeding. Analyses for genetic structure depicted structuring between species, i.e. strong species integrity. Within the species, all but one population pair were considered moderate to highly differentiated, i.e. no indication of extensive gene flow between populations. No overall correlation was observed between genetic and geographic distance of the pairwise species’ populations. In contrast to the pronounced genetic structure, there was no evidence of inbreeding within the populations, suggesting mechanisms favouring cross pollination and/or selection for more genetically diverse, heterozygous offspring. In conclusion, the data illustrate that the Neotropical Magnolias in the context of a fragmented landscape still have ample gene flow within populations, yet little gene flow between populations.

Highlights

Conservation genetics utilises a representative sample of DNA and organisms to quantify and study genetic diversityThese authors contributed : Emily Veltjen and Pieter Asselman Electronic supplementary material The online version of this article contains supplementary material, which is available to authorized users.Universidad de La Habana, C/ 25 e/ I y J, Vedado, La Habana, Cuba to preserve species as dynamic entities capable of coping with environmental change (Frankham et al 2010)
To investigate the general patterns of tree genetics in an empirical setting, and to contribute to the conservation of the species and forests under study, we focus on New World representatives of the tree genus Magnolia (Magnoliaceae) occurring at tropical latitudes, hereafter named Neotropical Magnolias
This study aims to (1) provide de novo developed SSR markers for Neotropical Magnolia species; (2) employ the SSR markers for genetic species delimitation between Caribbean Magnolia species; (3) search for patterns of extensive gene flow between Caribbean Magnoliaspecies and populations; and (4) test for signs of inbreeding within the Neotropical Magnolia populations

Summary

Introduction

Conservation genetics utilises a representative sample of DNA and organisms to quantify and study genetic diversity. A representative sampling of organisms can be interpreted at different levels: individuals for populations, populations for species, and species for ecosystems. The latter strategy makes use of the umbrella species concept (Roberge and Angelstam 2004)

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