Comparative Analysis of Apopellia endiviifolia Plastomes Reveals a Strikingly High Level of Differentiation between Its Terrestrial and Water Form

Jakub Sawicki,Monika Szczecińska,Katarzyna Krawczyk,Kamil Szandar,Monika Ślipiko

doi:10.3390/d13120674

Jakub Sawicki, Monika Szczecińska + Show 3 more

Open Access

https://doi.org/10.3390/d13120674

Copy DOI

Journal: Diversity	Publication Date: Dec 16, 2021
Citations: 5	License type: CC BY 4.0

Affiliation: University of Warmia and Mazury in Olsztyn

Abstract

The simple thalloid liverwort Apopellia endiviifolia is a widespread Holarctic species belonging to the family Pelliaceae. European populations of this species comprise two distinct evolutionary lineages named “species A”, known also as water form, and typical, mainly terrestrial forms named “species B”. Newly sequenced, assembled and annotated chloroplast genomes of six European specimens belonging to the two cryptic lineages occupying different microhabitats, revealed the structure typical for liverworts and previously sequenced reference. The plastomes of A. endiviifolia are 120,537–120,947 bp long with a structure typical for most plants, including a pair of IR regions (each of 9,092–9,207 bp) separated by LSC (82,506–82,609 bp) and SSC (19,854–19,924 bp) regions and consist of 121 unique genes, including 81 protein-coding genes, 6 genes of unknown function (ycf genes), 4 ribosomal RNAs and 30 transfer RNAs. Comparative analysis of typical, terrestrial and water forms revealed 4971 molecular diagnostic characters (MDCs), which exceeds numbers found in many well recognized liverworts taxa. Moreover, beside the presence of evolutionary hotspots like ycf1 and ycf2 genes and several intergenic spacer like ndhB-psbM, rps4-ndhJ and ndhC-atpE, the molecular identification of Apopellia cryptic species was possible by almost 98% of 500 bp long frames simulating mini barcodes. The different ecological niches can be driven by different pressures of positive selection, which was detected in nine genes including ccsA, ndhD, ndhF, petA, psbB, psbC, rpoB, ycf1 and ycf2. Despite clearly genetic differences and ecological preferences, the current observation of morphological differentiation does not no allow to separate terrestrial and water forms into taxonomic species.

Highlights

The cryptic speciation is well known to occur in all major lineages of liverworts [1,2,3,4,5,6]
An integrative approach based on morphology and molecular dataset enabled the split of the genus Pellia into Apopellia and Pellia sensu stricto [14]
As in the most known liverworts plastome sequences [23], plastomes of Apopellia consist of 121 unique genes, including 81 protein-coding genes, 6 genes of unknown function, 4 ribosomal RNAs and 30 transfer RNAs

Summary

Introduction

The cryptic speciation is well known to occur in all major lineages of liverworts [1,2,3,4,5,6]. In recent years integrative taxonomy approach led to description of several species of complex thalloids and leafy liverworts, previously considered as cryptic lineages distinguishable only on the basis of molecular markers [3,7]. The simple thalloid liverwort genus Pellia Raddi sensu lato is a widespread Holarctic taxon belonging to the family Pelliaceae, defined by several morphological characters. An integrative approach based on morphology and molecular dataset enabled the split of the genus Pellia into Apopellia and Pellia sensu stricto [14]. The former comprises three taxonomic species, A. apicola, A. megaspora and A. endiviifolia, with different patterns of distribution. The European population of Apopellia is diverging into two evolutionary lineages, which, besides molecular characters, differ in types of microhabitats [8,9,12]

Methods

Results

Conclusion