Conservation genetics and phylogeography of endangered and endemic shrub Tetraena mongolica (Zygophyllaceae) in Inner Mongolia, China

Xue-Jun Ge,Wei-Hsiang Huang,Kuo-Hsiang Hung,Zin-Huang Liu,Chi-Chun Huang,Chi-Chuan Hwang,Wei-Kuang Wang,Tzen-Yuh Chiang

doi:10.1186/1471-2156-12-1

Abstract

BackgroundTetraena mongolica (Zygophyllaceae), an endangered endemic species in western Inner Mongolia, China. For endemic species with a limited geographical range and declining populations, historical patterns of demography and hierarchical genetic structure are important for determining population structure, and also provide information for developing effective and sustainable management plans. In this study, we assess genetic variation, population structure, and phylogeography of T. mongolica from eight populations. Furthermore, we evaluate the conservation and management units to provide the information for conservation.ResultsSequence variation and spatial apportionment of the atpB-rbcL noncoding spacer region of the chloroplast DNA were used to reconstruct the phylogeography of T. mongolica. A total of 880 bp was sequenced from eight extant populations throughout the whole range of its distribution. At the cpDNA locus, high levels of genetic differentiation among populations and low levels of genetic variation within populations were detected, indicating that most seed dispersal was restricted within populations.ConclusionsDemographic fluctuations, which led to random losses of genetic polymorphisms from populations, due to frequent flooding of the Yellow River and human disturbance were indicated by the analysis of BEAST skyline plot. Nested clade analysis revealed that restricted gene flow with isolation by distance plus occasional long distance dispersal is the main evolutionary factor affecting the phylogeography and population structure of T. mongolica. For setting a conservation management plan, each population of T. mongolica should be recognized as a conservation unit.

Highlights

Tetraena mongolica (Zygophyllaceae), an endangered endemic species in western Inner Mongolia, China
For endemic species with a limited geographical range and declining populations, historical patterns of demography and hierarchical genetic structure are important for determining population structure, and provide information for developing effective and sustainable management plans [23]
We investigated genetic variation, population structure, and phylogeography of T. mongolica from eight populations throughout the entire distribution range

Summary

Introduction

Tetraena mongolica (Zygophyllaceae), an endangered endemic species in western Inner Mongolia, China. Understanding levels and spatial partitioning of genetic polymorphisms in an endangered species provides sufficient information for conservation practices. This kind of researches has become increasingly popular in the recent years, with the development of analytical methods to take phylogenetic distinctiveness into account when setting conservation priorities [11,12]. Given a haploid nature and a low frequency of genetic recombination, molecular markers of organelle DNA have been long used for phylogenetic reconstruction at various taxonomic levels, conservation genetics, and assessing the migratory routes of species [14,15]. With maternal inheritance [19], cpDNA is suitable for investigating processes associated with seed dispersal, such as range expansions [20] and the contribution of seed movement to total gene flow [21,22]

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Discussion

Conclusion