• Premise of the study: The Icacinaceae are a pantropical family of trees, shrubs, and climbers with an extensive Paleogene fossil record. Our improved understanding of phylogenetic relationships ...within the family provides an excellent context for investigating new fossil fruit and leaf material from the Eocene of western North America. • Methods: We examined fossils from early and middle Eocene sediments of western Wyoming, northeastern Utah, northwestern Colorado, and Oregon and compared them with extant species of lodes and other icacinaceous genera as well as previously described fossils of the family. • Key results: Three new fossil species are described, including two based on endocarps (Iodes occidentalis sp. nov. and Icacinicaryites lottii sp. nov.) and one based on leaves (Goweria bluerimensis sp. nov.). The co-occurrence of I. occidentalis and G. bluerimensis suggests these might represent detached organs of a single species. A new genus, Biceratocarpum, is also established for morphologically distinct fossil fruits of Icacinaceae previously placed in Carpolithus. Biceratocarpum brownii gen. et comb. nov. resembles the London Clay species "Iodes" corniculata in possessing a pair of subapical protrusions. • Conclusions: These fossils increase our knowledge of Icacinaceae in the Paleogene of North America and highlight the importance of the Northern Hemisphere in the early diversification of the family. They also document interchange with the Eocene flora of Europe and biogeographic connections with modern floras of Africa and Asia, where Icacinaceae are diverse today. The present-day restriction of this family to tropical regions offers ecological implications for the Eocene floras in which they occur.
The mulberry genus, Morus L. (Moraceae), has long been taxonomically difficult, and its species circumscription has only been defined recently. This genus comprises ca. 16 species distributed across ...Asia and the Americas, yet its biogeographic history remains poorly understood. In this study, we reconstructed the phylogeny and explored the biogeographic history of Morus using a combination of newly generated and previously published Hyb-Seq data. Our nuclear phylogeny recovered three well-supported geographic clades of Morus and showed that M. notabilis (China) is sister to the American clade plus the Asian clade. Multiple reticulation events among species of Morus and extensive incomplete lineage sorting (ILS) likely explain the difficulties in inferring phylogenetic relationships within the genus. Divergence time estimation indicated that Morus originated at the Eocene–Oligocene boundary, and current lineages started to diverge during the early Miocene, there is ambiguity surrounding the ancestral area with the two most likely regions being Sino-Himalaya or the Americas. Biogeographic inference and the fossil record suggest that Morus might have experienced extensive local extinction events during the Tertiary. Morus has expanded its distributional range through two dispersals from the Sino-Himalayan and Sino-Japanese regions to Southeast Asia. In summary, our new phylogenetic scheme and the biogeographic history presented here provide an essential foundation for understanding species relationships and the evolutionary history of Morus.
The Early Eocene (Ypresian) London Clay Formation contains one of the most important fruit and seed assemblages from the Paleogene, including a large diversity of taxa (>350 spp.) preserved as pyrite ...permineralizations retaining 3D structure as well as anatomical detail. Despite the importance of the flora for understanding angiosperm biogeographic and evolutionary history, the majority of the fossil material has not been revisited since the original taxonomic treatments by E.M. Reid and M.E.J. Chandler. Given subsequent advances in our understanding of angiosperm phylogeny and fruit morphology, coupled with technological advances in imaging/visualizing fossil material, many of the taxa represented in the flora deserve further study. Here we present a revision of the pantropical family Icacinaceae using X-ray micro-computed tomography (micro-CT) images of 21 species from the flora. Based on the results, four new combinations are made, a new fossil-genus is established for a distinctive species with affinities to the Phytocreneae, and emended diagnoses are provided for eight taxa. Of the seven genera recognized from the flora, only one, Iodes Blume, is extant. This study offers important insights on the biogeographic and evolutionary history of Icacinaceae, which is one of the most abundant and diverse components of the flora from the London Clay Formation.
Celotno besedilo
Dostopno za:
BF, DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Determining whether the high-latitude Bering land bridge (BLB) was ecologically suitable for the migration of mesothermal plants is significant for Holarctic phytogeographic inferences. ...Paleobotanical studies provide a critical source of data on the latitudinal positions of different plant lineages at different times, permitting assessment of the efficacy of the BLB for migration. Here we report exceptionally preserved fossils of Firmiana and Tilia endochrysea from the middle Miocene of South Korea. This represents a new reliable record of Firmiana and the first discovery of the T. endochrysea lineage in the fossil record of Asia. The occurrence of these fossils in South Korea indicates that the two lineages had a distribution that extended much farther north during the middle Miocene, but they were still geographically remote from the BLB. In light of the broader fossil record of Asia, our study shows that, in the middle Miocene, some mesothermal plants apparently inhabited the territory adjacent to the BLB and thus they were possibly capable of utilizing the BLB as a migratory corridor. Some other mesothermal plants, such as Firmiana and the T. endochrysea lineages, however, are restricted to more southern regions relative to the BLB based on current fossil evidence. These lineages may have been ecologically unable to traverse the BLB, which raises questions about the efficacy of the BLB as a universal exchange route for mesothermal plants between Asia and North America during the middle Miocene.
•A new reliable fossil record of Firmiana and the first fossil record of Tilia endochrysea lineages in Asia are described.•Firmiana and the T. endochrysea lineages had a more northernly distribution in the middle Miocene.•Our study shows that many, but not all, mesothermal lineages were ecologically capable of crossing the Bering land bridge in the middle Miocene.
The floristic treatment of Engler and Diels, published in 1901, provides the only infrageneric classification of the pantropical genus Xylopia (Annonaceae). Here we test and extend that ...classification using molecular and seed morphology characters. Phylogenetic relationships were reconstructed using data from four plastid regions obtained from 44 of the approximately 165 species in the genus, recovering four well-supported major clades. Seed characters were examined for these taxa, and six aril morphologies, three previously undocumented, were distinguished; we also document the presence of a sarcotesta on the seeds of many species. Molecular and seed data support recognition of five sections within the genus; one, Xylopia sect. Rugosperma, is proposed here as new. Our phylogenetic results suggest an African origin for the genus and reveal complex biogeographic patterns, likely facilitated by long-distance dispersal.
Cannabaceae are a relatively small family of angiosperms, but they include several species of huge economic and cultural significance: marijuana or hemp (Cannabis sativa) and hops (Humulus lupulus). ...Previous phylogenetic studies have clarified the most deep relationships in Cannabaceae, but relationships remain ambiguous among several major lineages. Here, we sampled 82 species representing all genera of Cannabaceae and utilized a new dataset of 90 nuclear genes and 82 chloroplast loci from Hyb‐Seq to investigate the phylogenomics of Cannabaceae. Nuclear phylogenetic analyses revealed a robust and consistent backbone for Cannabaceae. We observed nuclear gene‐tree conflict at several deep nodes in inferred species trees, also cyto‐nuclear discordance concerning the relationship between Gironniera and Lozanella and the relationships among Trema s.l. (including Parasponia), Cannabis + Humulus, and Chaetachme + Pteroceltis. Coalescent simulations and network analyses suggest that observed deep cyto‐nuclear discordances were most likely to stem from incomplete lineage sorting (ILS); nuclear gene‐tree conflict might be caused by both ILS and gene flow between species. All genera of Cannabaceae were recovered as monophyletic, except for Celtis, which consisted of two distinct clades: Celtis I (including most Celtis species) and Celtis II (including Celtis gomphophylla and Celtis schippii). We suggest that Celtis II should be recognized as the independent genus Sparrea based on both molecular and morphological evidence. Our work provides the most comprehensive and reliable phylogeny to date for Cannabaceae, enabling further exploration of evolutionary patterns across this family and highlighting the necessity of comparing nuclear with chloroplast data to examine the evolutionary history of plant groups.
Tanglegram showing the incongruence between the nuclear (left) and chloroplast (right) trees of Cannabaceae both inferred by partitioned RAxML analyses. Black lines connect the same taxa between the two trees. The colored branches indicate the major clades of Cannabaceae: black, outgroups; brown, Aphananthe; medium aquamarine, Gironniera; purple, Lozanella; red, Celtis II; light green, Chaetachme + Pteroceltis; green, Cannabis + Humulus; orange, Trema s.l.; and blue, Celtis I.
Icacinaceae Miers are a well-described family. However, the family lacks a comprehensive guide to endocarp morphology, which would be an important tool for interpreting the family’s extensive fossil ...record of endocarp remains. In this survey, we describe fruits and endocarps of 88 species of Icacinaceae s. str., four of Icacinaceae s. lat. (now Metteniusaceae) and one of Oncothecaceae. We investigated the value of the endocarp in species recognition. In addition, we generated an Xper3 database with an associated e-key to increase the availability of raw data and the understanding of the characters used. This study documents great diversity in epicarp hairs, mesocarp thickness, endocarp ornamentation, tubercle shape (if present), endocarp structure and thickness, and the locule lining. Some morphological features appear diagnostic for individual genera. In particular, the genus Iodes Blume, which is very common in the fossil record, is the only clade with the three following characters: papillae on the inner locule lining, ridged ornamentation on the endocarp surface, and a vascular bundle embedded within the endocarp wall. Finally, we discuss issues related to the preservation of fruit material in herbarium collections.
Premise of the study: We explored a targeted enrichment strategy to facilitate rapid and low-cost next-generation sequencing (NGS) of numerous complete plastid genomes from across the phylogenetic ...breadth of angiosperms. Methods and Results: A custom RNA probe set including the complete sequences of 22 previously sequenced eudicot plastomes was designed to facilitate hybridization-based targeted enrichment of eudicot plastid genomes. Using this probe set and an Agilent SureSelect targeted enrichment kit, we conducted an enrichment experiment including 24 angiosperms (22 eudicots, two monocots), which were subsequently sequenced on a single lane of the Illumina GAIIx with single-end, 100-bp reads. This approach yielded nearly complete to complete plastid genomes with exceptionally high coverage (mean coverage: 717×), even for the two monocots. Conclusions: Our enrichment experiment was highly successful even though many aspects of the capture process employed were suboptimal. Hence, significant improvements to this methodology are feasible. With this general approach and probe set, it should be possible to sequence more than 300 essentially complete plastid genomes in a single Illumina GAIIx lane (achieving ∼50× mean coverage). However, given the complications of pooling numerous samples for multiplex sequencing and the limited number of barcodes (e.g., 96) available in commercial kits, we recommend 96 samples as a current practical maximum for multiplex plastome sequencing. This high-throughput approach should facilitate large-scale plastid genome sequencing at any level of phylogenetic diversity in angiosperms.
Pyrite-permineralized fruits and seeds from the London Clay Formation (Ypresian; England) in the NHMUK are stored in silicone oil to retard decay processes. X-ray micro-computed tomography (micro-CT) ...has revealed internal morphology for multiple holotypes (including severely cracked and encrusted specimens) scanned in the protective fluid. Silicone oil alone has a similar X-ray attenuation to parts of the specimens, causing minor uncertainty for digitally rendered surfaces, but key systematic characters are readily visualized. Further work is needed to optimize visualization of fine-scale cellular detail. Labelling and segmentation to visualize important structures is achievable with these micro-CT datasets. However, manual labelling of individual slices is required, and defining boundaries between features can be difficult due to differential pyritization and silicone oil permeation. Digital sections through specimens can be made in any orientation and digital locule casts can be produced for studies in virtual taphonomy. These achievements have been accomplished with minimal risk to specimens, which remained in silicone oil and were studied within the museum. The datasets provide a potentially permanent record of at-risk specimens, can be made widely available to researchers unable to visit the collections and to other interested parties, and they enable monitoring for future conservation.
Celotno besedilo
Dostopno za:
BF, DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Introduction
The Millettioid/Phaseoloid (MP) clade of Fabaceae is globally distributed, economically important, and highly diverse, making it an attractive system for studying biogeographic and ...macroecological patterns at a global scale. We conducted the first global macroecological study to map and explore the environmental drivers of the MP clade's species richness patterns.
Methods
We compiled 116,212 species occurrences (161 genera) for the MP clade and 20 environmental variables (19 bioclimatic variables and elevation). Geospatial analyses were performed to estimate species richness patterns and biogeographic heterogeneity. The effects of environmental variables on the species richness of the MP clade were measured through multiple regression models.
Results
Our study identified the megathermal regions as hotspots of species richness for the MP clade. While species distributions and richness largely fit the latitudinal diversity gradient pattern, there was a significant negative relationship between the species richness of the MP clade along the latitude and longitude. The Afrotropic biogeographic realm had the highest alpha diversity (~36%); in terms of biome types, tropical and subtropical moist broadleaf forests had the highest alpha diversity (25%), while the beta diversity revealed a high dispersal rate and habitat tracking. Furthermore, the species richness was positively influenced by multiple climatic factors, with the mean diurnal range of temperatures and precipitation in the warmest quarter having strongest influence.
Discussion
Overall, the staggering species richness patterns could be explained by multiple diversity gradient hypotheses. Particularly, colder climates play a crucial role in shaping the species richness pattern by limiting the ecological opportunities for MP clade species in the higher latitudes of the Northern Hemisphere. This suggests that the species richness patterns of the MP clade can be described as "when dispersal meets adaptation." Our study provides a new basis for identifying priority regions for conservation of legumes.
PDF
