DOI: 10.5091/plecevo.177783

Authors: Justin T. Scholten, Chelsea D. Specht

Abstract: Background and aims – Reproductive plasticity and hybridization are known to play key roles in local adaptation and range expansion in plants, yet the environmental conditions under which canonical size-dependent models of sex expression break down remain poorly understood. Arisaema serratum (Araceae), a widespread species in Japan, has long been characterized as exhibiting size-dependent sex determination, whereby individuals transition from producing staminate to pistillate inflorescences upon reaching a size threshold. Field observations from western Japan further suggest that sex expression in A. serratum may be decoupled from plant size, raising the possibility that environmental cues such as light availability override intrinsic size thresholds in some populations. Because such ecological flexibility can increase spatial and temporal overlap among sympatric congeners, we additionally evaluate whether relaxed sex determination may coincide with increased introgression within this species complex. Materials and methods – We conducted field-based demographic surveys across five populations of Arisaema on Shikoku Island, Japan, quantifying plant size, sex expression, and light intensity to evaluate environmental and morphological predictors of reproductive phase. To assess hybridization, we generated genome-wide SNP data through genotyping-by-sequencing, constructed a maximum likelihood phylogeny, and performed f-branch analyses to detect patterns of introgression among sympatric species. Key results – Our data indicate that size in fact may not be the key factor in sex determination, with light availability emerging as a stronger predictor of sex expression than size alone for populations on Shikoku Island. Preliminary genomic analyses support evidence of gene flow between A. serratum and sympatric species, indicating ongoing hybridization and introgression. Conclusions – Our findings indicate that the shift away from a strict allometric model of sex determination on Shikoku Island to a photosensitive model allowing for diphasic sexual expression likely enhances reproductive flexibility and leads to an increase in seed production in open-canopy and disturbed environments. Together, these findings provide ecological and demographic insight contributing to the broad distribution, sex determination, and morphological diversity of A. serratum.

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DOI: 10.5091/plecevo.170279

Authors: Gaik Ee Lee, S. Robbert Gradstein, Xiaolan He, Julia Bechteler, Alfons Schäfer-Verwimp, Tamás Pócs

Abstract: Background and aims – The genus Lejeunea, with about 375 accepted species, is one of the most species-rich and intricate genera of liverworts. Here, we present the first integrative, worldwide infrageneric classification of Lejeunea based on morphology and molecular-phylogenetic analyses. Material and methods – Maximum likelihood analysis and Bayesian inference of sequences from two chloroplast regions (trnL-trnF, rbcL) and the nuclear ITS region of about 35% of the species, combined with morphological evidence. Key results and conclusions – The phylogenetic analyses revealed numerous robust clades within two major lineages, corresponding to subgenera Lejeunea and Crossotolejeunea. Integrating molecular phylogenetic evidence and morphological data, we describe 15 sections: four in subg. Lejeunea (sect. Glaucescentes, sect. Lamacerinae, sect. Lejeunea, sect. Macrolejeunea) and 11 in subg. Crossotolejeunea (sect. Apolejeunea, sect. Crossotolejeunea, sect. Echinocolea, sect. Flavae, sect. Heterolejeunea, sect. Inflatolejeunea, sect. Minutilobae, sect. Nanolejeunea, sect. Papillolejeunea, sect. Sordidae, sect. Xenantholejeunea). Four sections have a neotropical distribution, three are pantropical, two are pantropical and extend into temperate regions, two are Afro-American, two are Asian, one is Asian-Australasian, and one has a tropical amphi-Pacific range.

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DOI: 10.5091/plecevo.165188

Authors: Anneth Díaz-Reyes, Natalia Aguirre-Acosta, Carolina Feuillet-Hurtado, Ghennie Tatiana Rodríguez-Rey

Abstract: Background and aims – Ulex europaeus is an invasive allopolyploid (hexaploid) plant considered a global threat that has successfully colonized various regions, including the Northern Andes. This study aimed to assess its diversity and genetic structure in six sampling sites from the Central and Eastern Andes of the Northern Andes of Colombia, located in conservation-priority highland landscapes, using single nucleotide polymorphisms. Material and methods – Given the complex inheritance patterns of polyploids, both diploid and hexaploid datasets were analysed to estimate genetic diversity (e.g. Ho, He, FIS, and private alleles) and population structure (using e.g. FSTp, AMOVA, STRUCTURE, PCA, DAPC analyses). Additionally, the introduction history of the species in the Northern Andes, particularly the introduction from the Eastern to the Central Andes, was investigated using ABC-RF. Key results – Diploid and hexaploid datasets showed consistent clustering patterns, supporting predominantly disomic inheritance. Populations exhibited high heterozygosity (diploid: Ho = 0.302, He = 0.252; hexaploid: Ho = 0.483, He = 0.222). Genetic structure analyses showed moderate differentiation (FSTp = 0.118 for diploid; FSTp = 0.074 for hexaploid) and significant isolation by distance (diploid: r = 0.479, p value = 0.022; hexaploid: r = 0.507, p value= 0.012), but without a clearly defined spatial pattern, suggesting restricted gene flow influenced by external factors. ABC-RF analyses indicated at least two independent introduction events in the Eastern Andes, followed by multiple dispersal events into the Central Andes. Conclusion – Ulex europaeus populations in the Northern Andes maintain high heterozygosity and restricted gene flow. Polyploidy likely contributes to preserving genetic diversity, while multiple introduction events and human-mediated dispersal shape population structure, underscoring the complex invasion dynamics of this species in high-mountain ecosystems.

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DOI: 10.5091/plecevo.147801

Authors: Pablo Dupiol, Armel Chakocha, Marie-Louise Avana Tientcheu, Mohamed Mahamoud Charahabil, Cedric Mariac, Adeline Barnaud, Jérôme Duminil

Abstract: Background and aims – We developed a new set of nuclear microsatellite markers for Cola acuminata (Malvaceae), an important African food tree species commonly known as the kola nut. Probably originating from the tropical rainforests of the Congo Basin, C. acuminata is widely cultivated in the humid savannahs of the region where its nuts are sold throughout Central and West Africa for their stimulant properties. Nuclear microsatellite markers (SSRs) are well suited for assessing the genetic diversity and population structure of plant species due to their high variability. Material and methods – Leaf samples were collected from 84 C. acuminata cultivated individuals across three sites in Cameroon, two in the savannah zone, one in the forest zone. SSR markers were developed by sequencing genomic DNA from two individuals using an Illumina HiSeq platform. Genetic diversity was assessed based on 14 SSR markers genotyped in 84 individuals, and marker transferability to the closely related species Cola nitida was tested. Key results – Forty-eight new microsatellite loci were developed, of which 14 were polymorphic in C. acuminata. The results demonstrated a high level of genetic diversity with the presence of two to 33 alleles per locus (with an average of 14.14) across the three sites. The transferability of these markers was confirmed with 13 out of the 14 SSRs successfully amplifying in the closely related species, Cola nitida. Conclusion – These newly developed SSRs will be useful for assessing genetic diversity, genetic differentiation, and gene flow patterns of C. acuminata in the tropical forests of Central Africa. Preliminary results suggest genetic similarity between the two savannah sites. However, these two sites were significantly differentiated from the site in the forest zone. This suggests that the propagation material introduced in the savannah zone did not originate from the forest in southern Cameroon.

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DOI: 10.5091/plecevo.153974

Authors: Lu Tan, Meng Hu, Dan-Dan Wu, Yi-Ran Cheng, Li-Na Sha, Xing Fan, Hou-Yang Kang, Yi Wang, Ana Valdés-Florido, Hai-Qin Zhang, Yong-Hong Zhou

Abstract: Background and aims – Campeiostachys is an allohexaploid perennial genus of the Triticeae tribe (Poaceae). The allopolyploids of Triticeae are produced by interspecific hybridization of different genera. In this study, we investigate the genome origin of Campeiostachys and the relationships of some species based on phylogenetic analyses. Material and methods – Two nuclear (Acc1 and DMC1) and two chloroplast (matK and rps16) DNA regions of the species of Campeiostachys and its related genera were used for phylogenetic analyses. Key results – The Acc1 and DMC1 sequences revealed that the genome composition of all Campeiostachys species in our study is StYH, suggesting that Campeiostachys may have originated by the natural hybridization between species with StY and H genomes, as no species with Y or HY genomes have been found in the wild. The results from the chloroplast regions indicated that the maternal donor of the Campeiostachys species contains the St subgenome. In addition, phylogenetic analysis of the nuclear sequences showed that C. purpuraristata always groups with the species of the C. dahurica complex in the St, Y, or H clade, distinct from other species in the genus. Also, C. calcicola, C. kamoji, and C. tsukushiensis var. transiens are distinct yet closely related species. Conclusion – Campeiostachys species originated from the natural hybridization of the tetraploid species of Roegneria (StY) with the diploid species of Hordeum (H), with Roegneria (StY) acting as the maternal donor. Campeiostachys purpuraristata should be classified into the C. dahurica complex and treated as C. dahurica var. purpuraristata.

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DOI: 10.5091/plecevo.138834

Authors: Alejandra Lorena Goncalves, María Victoria García, Emilie Chancerel, Olivier Lepais, Myriam Heuertz

Abstract: Background and aims – Anadenanthera colubrina is a Neotropical native forest tree species with significant ecological importance in Seasonally Dry Tropical Forests. Developing genetic markers for this species is relevant for conservation, breeding, and evolutionary studies. Previously available genetic markers for A. colubrina consisted of a few microsatellites. Next-generation sequencing (NGS) strategies allow simple and cost-effective development of new SSR loci from low-coverage whole genome shotgun sequencing. The main aim was to develop microsatellite markers for sequence-based high-throughput genotyping (SSRseq) in the species and to characterize their information content against traditional capillary electrophoresis-based microsatellite data by estimating the amount of molecularly accessible size homoplasy of each locus. Additionally, the reliability of these markers for population genetic analysis was assessed by genotyping two age classes (reproductively mature trees and seedlings) in a typical location in Argentina. Key results – Sixty primer pairs targeting microsatellites were designed, of which 25 were validated with allelic error rates < 3% and genotype missingness < 20%. A significantly higher number of alleles per locus and heterozygosity was detected for SSRseq considering sequence polymorphisms compared to analysing the same data based on sequence size (length) only. Size homoplasy, calculated as the proportion of mismatches between datasets relative to the number of alleles differing in length, averaged 97.85% over all SSR loci. High levels of population genetic diversity were detected in adults and seedlings from Paranaense forests, exceeding those reported in previous studies of A. colubrina using traditional SSRs. The generated datasets increase the resolution of capillary-based microsatellite genotyping, allowing for more accurate inference of eco-evolutionary processes in non-model tree species.

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DOI: 10.5091/plecevo.84466

Authors: Jan-Adriaan Viljoen, Terry Hedderson, Charlotte Sletten Bjorå, Muthama Muasya

Abstract: Background and aims – Numerous lineages in the Western Cape of South Africa show affinities with the floras of tropical Africa and Australasia. Isolepis subgenus Fluitantes, comprising seven to nine species, includes the broadly-defined I. fluitans, which occurs throughout Africa into Europe and Asia, as well as on both sides of the Indian Ocean. Thus, it is well suited for testing the generality of both the Cape-to-Cairo pattern of dispersal and transoceanic dispersal between southern Africa and Australasia.Material and methods – We inferred a dated population-level phylogeny based on new sequence data from the nuclear ITS and the chloroplast atpI–H gene regions. We constructed dispersal–extinction–cladogenesis models in Lagrange to infer ancestral areas and to compare the likelihoods of stepping-stone and long-distance modes of dispersal.Key results – The Fluitantes originated in the Cape about 7 million years ago (mya). They spread stepwise onto the mountains of East Africa and thence into Europe and the islands of the Indian Ocean, seemingly tracking their ancestral habitat. Australasia was colonised by a single long-distance dispersal event ca 3 mya. Incongruence between the plastid and nuclear gene trees was apparent for the Australasian taxa, I. crassiuscula, I. lenticularis, and I. producta, with their atpI–H sequences placing them with I. ludwigii in the Fluitantes and the ITS nrDNA resolving them in the Proliferae. Furthermore, two African taxa (I. graminoides, I. inyangensis) diagnosed on unique morphology are resolved as part of the widespread I. fluitans.Conclusion – This study supports and extends the northward migration model that accounts for the Cape element of the Afromontane flora. Australasia was colonised directly from southern Africa, perhaps assisted by wind or waterfowl. Despite ancient hybridization associated with dispersal, we recognise the three taxa in Australasia as distinct, but synonymise I. graminoides and I. inyangensis into the widespread I. fluitans.

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DOI: 10.5091/plecevo.2020.1565

Authors: Myriam Heuertz, Henri Caron, Caroline Scotti-Saintagne, Pascal Pétronelli, Julien Engel, Niklas Tysklind, Sana Miloudi, Fernanda Gaiotto, Jérôme Chave, Jean-François Molino, Daniel Sabatier, João Loureiro, Katharina Budde

Abstract: Background and aims – The evolutionary history of Amazonia’s hyperabundant tropical tree species, also known as “hyperdominant” species, remains poorly investigated. We assessed whether the hyperdominant Eschweilera coriacea (DC.) S.A.Mori (Lecythidaceae) represents a single genetically cohesive species, and how its genetic constitution relates to other species from the same clade with which it occurs sympatrically in French Guiana.Methods – We sampled 152 individuals in nine forest sites in French Guiana, representing 11 species of the genus Eschweilera all belonging to the Parvifolia clade, with emphasis on E. coriacea. Samples were genotyped at four simple sequence repeat (SSR) markers. We delimited gene pools, i.e., genetically coherent putative taxa, using STRUCTURE software and principal component analysis. We compared the genetic assignment of individuals with their morphological species determination and estimated genetic diversity and differentiation for gene pools and species. We also estimated genome size using flow cytometry.Key results – SSR profiles commonly displayed up to four alleles per genotype, suggesting that the investigated Eschweilera species bear a paleopolyploid signature. Flow cytometry suggested that the studied species are diploid with haploid genome sizes of 871–1046 Mbp. We detected five gene pools and observed a good correspondence between morphological and genetic delimitation for Eschweilera sagotiana Miers and the undescribed morphospecies E. sp. 3 (which resembles E. grandiflora (Aubl.) Sandwith), and to a lesser extent for E. decolorans Sandwith and E. micrantha (O.Berg) Miers. Eschweilera coriacea was the most genetically diverse species and included individuals assigned to each gene pool. Conclusions – We found no conclusive evidence for cryptic species within E. coriacea in French Guiana. SSRs detected fewer gene pools than expected based on morphology in the Parvifolia clade but discriminated evolutionary relationships better than available plastid markers. A positive trend between demographic abundance of species and allelic richness illustrates that hyperdominants may have a high evolutionary potential. This hypothesis can be tested using more powerful genomic data in combination with tree phenotypic trait variation and characterization of niche breadth, to enhance our understanding of the causes of hyperdominance in Amazonian trees.

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