Nadja Korotkova

What does it take to resolve relationships and to identify species with molecular markers? An example from the epiphytic Rhipsalideae (Cactaceae)

UNLABELLED PREMISE OF THE STUDY The Cactaceae are a major New World plant family and popular in horticulture. Still, taxonomic units and species limits have been difficult to define, and molecular phylogenetic studies so far have yielded largely unresolved trees, so relationships within Cactaceae remain insufficiently understood. This study focuses on the predominantly epiphytic tribe Rhipsalideae and evaluates the utility of a spectrum of plastid genomic regions. • METHODS We present a phylogenetic study including 52 of the 53 Rhipsalideae species and all the infraspecific taxa. Seven regions (trnK intron, matK, rbcL, rps3-rpl16, rpl16 intron, psbA-trnH, trnQ-rps16), ca. 5600 nucleotides (nt) were sequenced per sample. The regions used were evaluated for their phylogenetic performance and performance in DNA-based species recognition based on operational taxonomic units (OTUs) defined beforehand. • KEY RESULTS The Rhipsalideae are monophyletic and contain five clades that correspond to the genera Rhipsalis, Lepismium, Schlumbergera, Hatiora, and Rhipsalidopsis. The species-level tree was well resolved and supported; the rpl16 and trnK introns yielded the best phylogenetic signal. Although the psbA-trnH and trnQ-rps16 spacers were the most successful individual regions for OTU identification, their success rate did not significantly exceed 70%. The highest OTU identification rate of 97% was found using the combination of psbA-trnH, rps3-rpl16, trnK intron, and trnQ-rps16 as a minimum possible marker length (ca. 1660 nt). • CONCLUSIONS The phylogenetic performance of a marker is not determined by the level of sequence variability, and species discrimination power does not necessarily correlate with phylogenetic utility.

The petD group II intron as a species level marker: utility for tree inference and species identification in the diverse genus Campanula (Campanulaceae).

Abstract Borsch T., Korotkova N., Raus T., Lobin W. & Löhne C.: The petD group II intron as a species level marker: utility for tree inference and species identification in the diverse genus Campanula (Campanulaceae). — Willdenowia 39: 7–33. — Online ISSN 1868-6397;

Variability among the Most Rapidly Evolving Plastid Genomic Regions is Lineage-Specific: Implications of Pairwise Genome Comparisons in Pyrus (Rosaceae) and Other Angiosperms for Marker Choice

Plastid genomes exhibit different levels of variability in their sequences, depending on the respective kinds of genomic regions. Genes are usually more conserved while noncoding introns and spacers evolve at a faster pace. While a set of about thirty maximum variable noncoding genomic regions has been suggested to provide universally promising phylogenetic markers throughout angiosperms, applications often require several regions to be sequenced for many individuals. Our project aims to illuminate evolutionary relationships and species-limits in the genus Pyrus (Rosaceae)—a typical case with very low genetic distances between taxa. In this study, we have sequenced the plastid genome of Pyrus spinosa and aligned it to the already available P. pyrifolia sequence. The overall p-distance of the two Pyrus genomes was 0.00145. The intergenic spacers between ndhC–trnV, trnR–atpA, ndhF–rpl32, psbM–trnD, and trnQ–rps16 were the most variable regions, also comprising the highest total numbers of substitutions, indels and inversions (potentially informative characters). Our comparative analysis of further plastid genome pairs with similar low p-distances from Oenothera (representing another rosid), Olea (asterids) and Cymbidium (monocots) showed in each case a different ranking of genomic regions in terms of variability and potentially informative characters. Only two intergenic spacers (ndhF–rpl32 and trnK–rps16) were consistently found among the 30 top-ranked regions. We have mapped the occurrence of substitutions and microstructural mutations in the four genome pairs. High AT content in specific sequence elements seems to foster frequent mutations. We conclude that the variability among the fastest evolving plastid genomic regions is lineage-specific and thus cannot be precisely predicted across angiosperms. The often lineage-specific occurrence of stem-loop elements in the sequences of introns and spacers also governs lineage-specific mutations. Sequencing whole plastid genomes to find markers for evolutionary analyses is therefore particularly useful when overall genetic distances are low.

A phylogenetic analysis of Pfeiffera and the reinstatement of Lymanbensonia as an independently evolved lineage of epiphytic Cactaceae within a new tribe Lymanbensonieae

Abstract Korotkova N., Zabel L., Quandt D. & Barthlott W.: A phylogenetic analysis of Pfeiffera and the reinstatement of Lymanbensonia as an independently evolved lineage of epiphytic Cactaceae within a new tribe Lymanbensonieae. — Willdenowia 40: 151–172, S1–S4. — Online ISSN 1868–6397;

On the thermogenesis of the Titan arum (Amorphophallus titanum)

The Titan arum (Araceae) is one of the most famous flowering plants producing the largest bloom of all flowering plants. Its flowering period of two days is divided into a female flowering phase in the first night and a male flowering phase in the second night. Recently, we have documented thermogenesis in the spadix of the Titan arum during the female flowering phase. Here, we document a second thermogenic phase in which the male florets are heated during the male flowering phase. Obviously the two nocturnal thermogenic phases are linked with the two flowering periods. These observations now allow a more detailed understanding of the flowering behavior of the Titan arum.

Dynamic diversification history with rate upshifts in Holarctic bell‐flowers (Campanula and allies)

Campanula s.l. is one of the most speciose flowering plant lineages of the Holarctic (ca. 600 species). In the present study we sequenced three regions of the plastid genome (petD, rpl16 and trnK/matK) across a broad sample of Campanula s.l., which markedly improved phylogenetic resolution and statistical support compared to previous studies. Based on this robust phylogenetic hypothesis we estimated divergence times using BEAST, diversification rate shifts using Bayesian Analysis of Macroevolutionary Mixture (BAMM) and TreePar, and ancestral ranges using Biogeography with Bayesian (and likelihood) Evolutionary Analyses in R. Campanula s.l. is estimated to have originated during the Early Eocene but the major diversification events occurred between the Late Oligocene and Middle Miocene. Two upward diversification rate shifts were revealed by BAMM, specific to the crown nodes of two Campanula clades: CAM17, a mostly South European‐SW Asian lineage originating during the Middle Miocene and containing nearly half of all known Campanula species; and CAM15B, a SW Asian–Sino‐Himalayan lineage of nine species originating in the early Pleistocene. The dynamic diversification history of Campanula and the inferred rate shifts are discussed in a geo‐historical context.

Development of Nuclear Microsatellites for the Arcto-Tertiary Tree Zelkova carpinifolia (Ulmaceae) Using 454 Pyrosequencing

Premise of the study: The current study aimed at developing nuclear microsatellite markers for the relict tree species Zelkova carpinifolia, which is threatened in its natural range in the South Caucasus. Methods and Results: Pyrosequencing of an enriched microsatellite library on the Roche FLX platform using the 454 Titanium kit produced 86,058 sequence reads, most of which contained short tandem repeats. Eighty microsatellite loci identified using the software package QDD version 1 were selected and tested for proper PCR amplification. Of these, 13 allowed proper amplification and were shown to be polymorphic among a sample of 25 Z. carpinifolia specimens from various geographic origins. Conclusions: The set of microsatellite markers will be suitable for the assessment of genetic diversity in Z. carpinifolia. They will allow for an examination of phylogeographic patterns as well as of population structure and gene flow within this species.

Using the EDIT Platform for Cybertaxonomy to prepare and publish a treatment for the Caryophyllales Network: an online synthesis of the Nepenthaceae

Abstract: The Caryophyllales Network strives to assemble an online dynamic synthesis of the order Caryophyllales, uniting the current knowledge about the phylogeny of the order with up-to-date information on the individual taxa contained. Capturing taxonomic data and the decision processes involved in the definition and circumscription of the taxa requires highly complex specialized software. The Caryophyllales Network uses the EDIT Platform for Cybertaxonomy for that purpose. In the context of the online treatment of the family Nepenthaceae, we describe the steps taken to assemble the database, the interaction with other electronic sources, the links with the World Flora Online initiative, and the prospects for the maintenance and further development of the Nepenthaceae segment of the Caryophyllales database. Nepenthaceae constitute an example of a family with a relatively recent flora treatment (Flora Malesiana, published in 2001), which to a large extent covers its total range of distribution, but with further species subsequently described as new to science in mostly regional treatments, and with an analysis of relationships and species limits on the basis of evolutionary methods just emerging. A snapshot of the current state of the database is provided as an annotated checklist in PDF format in the Supplementary Material online, which includes 176 species and nine naturally occurring named hybrids and treats 435 species and infraspecific names. Citation: Berendsohn W. G., Borsch T., Güntsch A., Kohlbecker A., Korotkova N., Luther K., Müller A., Plitzner P. & Mering S. von 2018: Using the EDIT Platform for Cybertaxonomy to prepare and publish a treatment for the Caryophyllales Network: an online synthesis of the Nepenthaceae. – Willdenowia 48: 335–344. doi: https://doi.org/10.3372/wi.48.48301 Version of record first published online on 17 September 2018 ahead of inclusion in December 2018 issue.

Towards resolving the evolutionary history of Caucasian pears (Pyrus, Rosaceae) - Phylogenetic relationships, divergence times and leaf trait evolution

With approximately 25 endemic species, the genus Pyrus (pears) is highly diverse in the Caucasus ecoregion. The majority of Caucasian pears inhabit xerophytic open woodlands or similar habitats, to which they display morphological adaptations, such as narrow leaves. The other species, both Caucasian and non‐Caucasian taxa, mainly inhabit mesophytic forests and display broad leaves. Using a representative taxon sampling of Pyrus from the Caucasus, Europe and Asia, we reconstruct phylogenetic relationships in the genus based on multiple plastid regions. We also estimate the divergence times of major clades in Pyrus, reconstruct the evolution of leaf shapes, and discuss the emergence of xeromorphic leaf traits. Our results confirm the monophyly of Pyrus and the existence of two major clades: (a) an E Asian clade with a crown group age of 15.7 (24.02–8.37 95% HPD) My, and (b) a W Eurasian clade that comprises species from Europe, SW Asia and the Caucasus and that displays a slightly younger crown group of 12.38 (19.02–6.41 95% HPD) My. The existing infrageneric classification of Pyrus was found partially incongruent with the inferred phylogenetic trees. Several currently accepted species were not recovered as monophyletic, indicating that current species limits require re‐evaluation. Ancestral character state reconstructions revealed several independent transitions from broad‐ to narrow‐shaped leaves in Pyrus, probably via intermediate‐shaped leaves.

Phylogeny and diversification history of the large Neotropical genus Philodendron (Araceae): Accelerated speciation in a lineage dominated by epiphytes

PREMISE OF THE STUDY Philodendron is a large genus of ~560 species and among the most conspicuous epiphytic components of Neotropical forests, yet its phylogenetic relationships, timing of divergence, and diversification history have remained unclear. We present a comprehensive phylogenetic study for Philodendron and investigate its diversification, including divergence-time estimates and diversification rate shift analyses. METHODS We performed the largest phylogenetic reconstruction for Philodendron to date, including 125 taxa with a combined dataset of three plastid regions (petD, rpl16, and trnK/matK). We estimated divergence times using Bayesian evolutionary analysis sampling trees and inferred shifts in diversification rates using Bayesian analysis of macroevolutionary mixtures. KEY RESULTS We found that Philodendron, its three subgenera, and the closely related genus Adelonema are monophyletic. Within Philodendron subgenus Philodendron, 12 statistically well-supported clades are recognized. The genus Philodendron originated ~25 mya and a diversification rate upshift was detected at the origin of subgenus Philodendron ~12 mya. CONCLUSIONS Philodendron is a species-rich Neotropical lineage that diverged from Adelonema during the late Oligocene. Within Philodendron, the three subgenera currently accepted are recovered in two lineages: one contains the subgenera Meconostigma and Pteromischum and the other contains subgenus Philodendron. The lineage containing subgenera Meconostigma and Pteromischum underwent a consistent diversification rate. By contrast, a diversification rate upshift occurred within subgenus Philodendron ~12 mya. This diversification rate upshift is associated with the species radiation of the most speciose subgenus within Philodendron. The sections accepted within subgenus Philodendron are not congruent with the clades recovered. Instead, the clades are geographically defined.