Hrones, M. | bioRxiv Science

bioRxiv2024

Plant kleptomaniacs: geographic genetic patterns in the amphi-apomictic Rubus ser. Glandulosi (Rosaceae) reveal complex reticulate evolution of Eurasian brambles

Rubus ser. Glandulosi represents a unique model of geographic parthenogenesis on a homoploid (4x) level. We employed double digest restriction-site associated DNA sequencing (ddRADseq) in 587 individuals of different Rubus taxa and modelling of suitable climate to characterize evolutionary and phylogeographic patterns and shed light on the geographic differentiation of apomicts and sexuals. Six ancestral species were identified that contributed to the contemporary gene pool of R. ser. Glandulosi. While sexuals were introgressed from R. dolichocarpus and R. moschus in West Asia and from R. ulmifolius agg., R. canescens and R. incanescens in Europe, apomicts were characterized by alleles of R. subsect. Rubus. Gene flow between sexuals and apomicts was also detected, as well as occasional hybridization with other taxa. We hypothesize that sexuals survived the last glacial period in several large southern refugia, whereas apomicts were mostly restricted to southern France from whence they quickly recolonized Central and Western Europe. The secondary contact of sexuals and apomicts was probably the principal factor that established geographic parthenogenesis in R. ser. Glandulosi. Sexual populations are not impoverished in genetic diversity along their borderline with apomicts and maladaptive population genetic processes likely did not shape the geographic patterns. HighlightsO_LIGeographic parthenogenesis in Rubus ser. Glandulosi is caused by secondary contact C_LIO_LIReticulate evolution in Eurasian brambles is more extensive than expected C_LIO_LIAt least six species contributed to the evolution of Rubus ser. Glandulosi C_LIO_LIExtinct ancestors gene pool is associated with apomixis C_LI O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=79 SRC="FIGDIR/small/575855v1_ufig1.gif" ALT="Figure 1"> View larger version (51K): org.highwire.dtl.DTLVardef@a25ccforg.highwire.dtl.DTLVardef@17b1a5corg.highwire.dtl.DTLVardef@ffa036org.highwire.dtl.DTLVardef@6f6e0e_HPS_FORMAT_FIGEXP M_FIG O_FLOATNOGraphical abstractC_FLOATNO C_FIG

evolutionary biology↗

bioRxiv2023

Cytogeography of Gagea bohemica (Liliaceae) outside the Mediterranean: two ploidy levels, spatial differentiation of cytotypes, and occurrence of mixed-ploidy populations

Gagea bohemica s. lat. is a morphologically and karyologically highly variable group with many morphologically similar "narrow" taxa currently considered as a single variable species. It is predominantly distributed in Mediterranean and warmer parts of temperate belt of Europe. The large-scale data on its cytogeography and population cytotype structure which could provide a basis for taxonomy is lacking, only scattered data on ploidy have been published from various parts of its range. In this study, we sampled 106 populations in broader Central Europe, the northeastern Balkan Peninsula and the northwestern Black Sea coast in order to analyse their ploidy level, genome size and pollen stainability. Two cytotypes, i.e., tetraploid (2n = 48) and pentaploid (2n = 60), were found in the study area using chromosome counting and flow cytometry, both in pure and mixed-ploidy populations. Pure pentaploid populations are mainly distributed in Austria, Czechia, northwestern Hungary and Slovakia while tetraploid cytotype in pure and mixed-ploidy populations forming two lineages which are concentrated into two disjunct geographical areas: a western lineage in Germany and Switzerland, and an eastern one in Bulgaria, southeastern Hungary, northern Greece, Romania, Serbia and Ukraine. The two lineages differ in their genome size regardless of their ploidy, indicating their independent origin. Analysis of pollen stainability using a modified Alexander stain revealed an unusual pattern with tetraploids having a lower pollen stainability (mean 44.29 %) than pentaploids (mean 70.70 %) but the western and eastern populations differed again from each other.

plant biology↗