Morphological and Genome-Wide Evidence of Homoploid Hybridisation in Urospermum (Asteraceae)

The genus Urospermum is distributed in the Mediterranean region and Macaronesia, and has been introduced to other extra-Mediterranean regions. Although the two species constituting the genus, U. dalechampii and U. picroides, are frequently found together, hybrids have so far only been reported once, from Morocco. However, we found certain individuals in Catalonia, whose intermediate morphology suggested a potential hybrid origin. In this study, we applied morphological and molecular methods to investigate the origin of those individuals. Intermediate features at phenotype, karyological, cytogenetic, and genomic levels were identified in morphologically intermediate individuals, supporting their homoploid hybrid origin. Chloroplast sequence data suggest that U. dalechampii is the maternal progenitor of the hybrid. Together with the intermediate traits displayed, the lack of fertile seeds suggests that hybrids are probably F1. Future monitoring studies will be, nonetheless, needed to evaluate the extent of hybridisation and its potential impact on the biology of the genus.

Gene Flow and Diversification in Himalopsyche martynovi Species Complex (Trichoptera: Rhyacophilidae) in the Hengduan Mountains

The Hengduan Mountains are one of the most species-rich mountainous areas in the world. The origin and evolution of such a remarkable biodiversity are likely to be associated with geological or climatic dynamics, as well as taxon-specific biotic processes (e.g., hybridization, polyploidization, etc.). Here, we investigate the mechanisms fostering the diversification of the endemic Himalopsyche martynovi complex, a poorly known group of aquatic insects. We used multiple allelic datasets generated from 691 AHE loci to reconstruct species and RaxML phylogenetic trees. We selected the most reliable phylogenetic tree to perform network and gene flow analyses. The phylogenetic reconstructions and network analysis identified three clades, including H. epikur, H. martynovi sensu stricto and H. cf. martynovi. Himalopsyche martynovi sensu stricto and H. cf. martynovi present an intermediate morphology between H. epikur and H. viteceki, the closest known relative to the H. martynovi-complex. The gene flow analysis revealed extensive gene flow among these lineages. Our results suggest that H. viteceki and H. epikur are likely to have contributed to the evolution of H. martynovi sensu stricto and H. cf. martynovi via gene flow, and thus, our study provides insights in the diversification process of a lesser-known ecological group, and hints at the potential role of gene flow in the emergence of biological novelty in the Hengduan Mountains.

Gene Flow and Diversification in Himalopsyche Martynovi Species Complex (Trichoptera: Rhyacophilidae) In the Hengduan Mountains

Background: The Hengduan Mountains are one of the most species–rich mountainous areas in the world. The origin and evolution of such a remarkable biodiversity are likely to be associated with geological or climatic dynamics, as well as taxon-specific biotic processes (e.g., hybridization, polyploidization, etc.). Here, we investigate the mechanisms fostering the diversification of the endemic Himalopsyche martynovi complex, a poorly known group of aquatic insects. Methods: We used multiple allelic datasets generated from 691 AHE loci to reconstruct species and RaxML phylogenetic trees. We selected the most reliable phylogenetic tree to perform network and gene flow analyses. Results: Phylogenetic reconstructions and network analysis identified three clades, including H. epikur, H. martynovi sensu stricto and H. cf. martynovi. Himalopsyche martynovi sensu stricto and H. cf. martynovi present an intermediate morphology between H. epikur and H. viteceki, the closest known relative to the H. martynovi–complex. The gene flow analysis revealed extensive gene flow among these lineages. Conclusion: Our results suggest that H. viteceki and H. epikur are likely to have contributed to the evolution of H. martynovi sensu stricto and H. cf. martynovi via gene flow, and thus, our study provides insights in the diversification process of a lesser–known ecological group, and hints at the potential role of gene flow in the emergence of biological novelty in the Hengduan Mountains.

Asymmetric hybridization origin of Rhododendron agastum (Ericaceae) in Guizhou, China

Rhododendron is one of the famous flowers in the world. Four wild Rhododendron species, namely, R. delavayi Franch., R. agastum Balf. f. et W. W. Smith., R. decorum Franch., and R. irroratum Franch., belong to subgenus Hymenanthes, which are sympatrically distributed in the Baili Rhododendron Nature Reserve of Guizhou Province, China. The intermediate morphology of R. agastum in the reserve, which is between R. delavayi and R irroratum or between R. delavayi and R. decorum, has been speculated that R. agastum is a hybrid of one of the two combinations. However, the exact parentage of R. agastum in the reserve remains controversial. In this study, the four Rhododendron species were investigated to identify the parental origin of R. agastum based on 13 morphological characteristics, 20 co-dominant inherited microsatellite markers, and two maternal inherited plastid DNA makers. Results of genetic structure and origin scenario clearly support that R. agastum is a natural hybrid between R. delavayi and R. irroratum rather than R. delavayi and R. decorum, which is consistent with their morphological characteristics. In addition, hybridization analysis indicates that R. agastum is dominated by F2 generation in the reserve. Furthermore, haplotype analysis suggests that natural hybridization between R. delavayi and R. irroratum is bidirectional but asymmetric with R. delavayi, the main maternal parent of R. agastum. Our results provide theoretical basis for future utilization and conservation of genetic resources of these Rhododendron species.

Ionopsis × atalibae (Orchidaceae, Oncidiinae), a new natural hybrid from the Brazilian Amazon

Hybridization plays a relevant role in the evolution and diversification of flowering plants. Natural hybridization has been commonly recorded in some orchid groups. During fieldwork in a Citrus plantation in the Brazilian Amazon, plants of Ionopsis utricularioides, I. satyrioides and an unidentified taxon with intermediate morphology between both sympatric species were found. The plants with intermediate features are most likely a natural hybrid between I. utricularioides and I. satyrioides described here as I. × atalibae.

New early Pleistocene Alligator (Eusuchia: Crocodylia) from Florida bridges a gap in Alligator evolution

The American Alligator (Alligator mississippiensis) is one of two species of Alligator in the modern world. It is only distantly related to the other extant species (A. sinensis), with much closer relatives known from the geologic past of North America. A disparity exists, though, in the fossil record between A. mississippiensis and its close relative, the late Miocene (?)—early Pliocene A. mefferdi. While A. mississippiensis is known from the mid-Pleistocene and later, few Alligator remains were known from the earliest Pleistocene of North America until the discovery of the Haile 7C and 7G early Pleistocene (Blancan Land Mammal Age) sites from Alachua County, Florida. The Haile alligators exhibit a suite of characters from both A. mississippiensis and A. mefferdi, displaying intermediate morphology in time. The Haile alligators are distinct from either of the aforementioned taxa, and a new species, Alligator hailensis is suggested, bridging an important gap in the evolution of the American Alligator.

Ultrastructure of the Bacteriocytes in the Midgut of the Carpenter ant Camponotus rufipes: Endosymbiont Control by Autophagy

The carpenter ant Camponotus rufipes has intracellular bacteria in bacteriocytes scattered in the midgut epithelium, which have different amounts of endosymbionts, according to the developmental stages. However, there are no detailed data about the midgut cells in adult workers. The present work aimed to evaluate the morphology and cellular events that coordinate the abundance of endosymbionts in the midgut cells in C. rufipes workers. The midgut epithelium has digestive cells, bacteriocytes, and cells with intermediate morphology. The latter is similar to bacteriocytes, due to the abundance of endosymbionts, and similar to digestive cells, due to their microvilli. The digestive and intermediate cells are rich in autophagosomes and autolysosomes, both with bacteria debris in the lumen. These findings suggest that midgut cells of C. rufipes control the endosymbiont level by the autophagy pathway.

Morphological, Molecular, and Biogeographic Evidence for Specific Recognition of Euthamia hirtipes and Euthamia scabra (Asteraceae, Astereae)

Abstract—The number and identity of species within Euthamia (Asteraceae, Astereae) have varied considerably among taxonomic treatments. Euthamia graminifolia (L.) Nutt. is often treated broadly, including plants from the northern and eastern United States and Canada, including the Atlantic and Gulf Coasts. Broad-leaved, largely glabrous plants from New Jersey to the Florida Panhandle have been inconsistently treated as E. graminifolia, E. graminifolia var. hirtipes (Fernald) C.E.S. Taylor & R.J. Taylor, E. hirtipes (Fernald) Sieren, or a hybrid between E graminifolia and E. caroliniana (L.) Greene ex Porter & Britton. Similarly, plants from the Florida Panhandle to eastern Louisiana have been incorporated into E. graminifolia or E. graminifolia var. hirtipes with only Greene in 1902 recognizing these plants as a distinct species, E. scabra Greene. To determine the identity and proper rank of these entities, morphological and phylogenetic analyses were performed to evaluate relationships within Euthamia. Plants from the Atlantic Coast most morphologically resemble Gulf Coast plants which similarly resemble E. gymnospermoides Greene. The Gulf Coast plants and E. gymnospermoides share similar DNA sequences while the Atlantic Coast plants represent a unique clade. Neither Gulf Coast nor Atlantic Coast plants contain highly polymorphic sequences, indicating that they are not hybrids. Occasional plants found within southernmost Alabama and the Florida Panhandle have polymorphic sequences and intermediate morphology however, suggesting that putative hybrids exist between Gulf and Atlantic Coast plants. This study concludes that both entities deserve specific rank as E. scabra Greene for scabrous plants along the central Gulf Coast and E. hirtipes (Fernald) Sieren for largely glabrous plants mostly along the Atlantic Coast. Ecological niche modeling indicates that precipitation, especially during summer months, and soils, namely coarse fragments and sand content, drive the distribution of these organisms, largely restricted to either side of the Apalachicola River serving as a distributional barrier.

Morphological characters and SNP markers suggest hybridization and introgression in sympatric populations of the pleurocarpous mosses Homalothecium lutescens and H. sericeum

Hybridization in bryophytes involves a fusion of gametes produced by haploid parental gametophytes of different species. The primary hybrid is thus the short-lived diploid sporophyte, which soon undergoes meiosis prior to the formation of large amounts of haploid spores. We compared morphology of gametophytes (branch leaves) and sporophytes (capsule inclination) from sympatric populations and allopatric populations of H. lutescens and H. sericeum. In addition, we used transcriptome data to select 85 nuclear SNP markers that were fixed for alternative alleles in the two species. The SNPs were used to estimate the degree of hybridization in diploid sporophytes. Our study shows that gametophytes from sympatric populations display intermediate morphology in a number of leaf characters, with exception for leaf sizes, which are markedly smaller than those in allopatric populations. None of the 100 sporophytes appeared to be primary hybrids, but 33 displayed admixing—heterozygotic expression of SNP markers or mismatch of occasional markers in homozygous condition—suggesting that extensive introgression takes place in the sympatric populations. Most sporophytes with intermediate capsule inclination, initially classed as putative hybrids, did not display admixture of nuclear SNP markers. Sixty-seven percent of admixed sporophytes have predominantly nuclear SNPs typical for H. lutescens. Our results suggest that interspecific hybridization and bidirectional introgression are relatively common in the studied sympatric populations, giving rise to viable recombinants, but not complete mixing of the parental genomes. Our study is one of the first detailed accounts of hybridization among pleurocarpous mosses, opening for future studies of gene transfer and introgression between bryophyte lineages and its role in local adaptation and long-term evolutionary diversification.

SEM study of a topotype population of Paracrobeles psammophilus Navarro & Lluch, 1999 (Rhabditida: Cephalobidae) and its taxonomic implications

Summary Paracrobeles psammophilus from the type locality is redescribed based on SEM studies. In addition, material of P. psammophilus previously described from Sicily (Italy) is revised. Species of Paracrobeles are analysed and form two morphological groups: the laterellus-group with three species (P. kelsodunensis, P. laterellus and P. mojavicus) having a lip region with two guard processes at both primary and secondary axils and shorter and more robust spicules, and the psammophilus-group with two species (P. deserticola and P. psammophilus) having primary axils bearing two guard processes and secondary axils with only one guard process and longer and slender spicules. Another four species (Acrobelinema cornis, Cervidellus cancellatus, C. rarus and C. sonorensis), having an intermediate morphology between Paracrobeles and Nothacrobeles, are transferred to Nothacrobeles (= Acrobelinema n. syn.).