A continuous morphological approach to study the evolution of pollen in a phylogenetic context: An example with the order Myrtales

The study of pollen morphology has historically allowed evolutionary biologists to assess phylogenetic relationships among Angiosperms, as well as to better understand the fossil record. During this process, pollen has mainly been studied by discretizing some of its main characteristics such as size, shape, and exine ornamentation. One large plant clade in which pollen has been used this way for phylogenetic inference and character mapping is the order Myrtales, composed by the small families Alzateaceae, Crypteroniaceae, and Penaeaceae (collectively the “CAP clade”), as well as the large families Combretaceae, Lythraceae, Melastomataceae, Myrtaceae, Onagraceae and Vochysiaceae. In this study, we present a novel way to study pollen evolution by using quantitative size and shape variables. We use morphometric and morphospace methods to evaluate pollen change in the order Myrtales using a time-calibrated, supermatrix phylogeny. We then test for conservatism, divergence, and morphological convergence of pollen and for correlation between the latitudinal gradient and pollen size and shape. To obtain an estimate of shape, Myrtales pollen images were extracted from the literature, and their outlines analyzed using elliptic Fourier methods. Shape and size variables were then analyzed in a phylogenetic framework under an Ornstein-Uhlenbeck process to test for shifts in size and shape during the evolutionary history of Myrtales. Few shifts in Myrtales pollen morphology were found which indicates morphological conservatism. Heterocolpate, small pollen is ancestral with largest pollen in Onagraceae. Convergent shifts in shape but not size occurred in Myrtaceae and Onagraceae and are correlated to shifts in latitude and biogeography. A quantitative approach was applied for the first time to examine pollen evolution across a large time scale. Using phylogenetic based morphometrics and an OU process, hypotheses of pollen size and shape were tested across Myrtales. Convergent pollen shifts and position in the latitudinal gradient support the selective role of harmomegathy, the mechanism by which pollen grains accommodate their volume in response to water loss

The symmetry spectrum in a hybridising, tropical group of rhododendrons

Many diverse plant clades possess bilaterally symmetrical flowers and specialised pollination syndromes, suggesting that these traits may promote diversification. We examined the evolution of diverse floral morphologies in a species‐rich tropical radiation of Rhododendron. We used restriction‐site associated DNA sequencing on 114 taxa from Rhododendron sect. Schistanthe to reconstruct phylogenetic relationships and examine hybridisation. We then captured and quantified floral variation using geometric morphometric analyses, which we interpreted in a phylogenetic context. We uncovered phylogenetic conflict and uncertainty caused by introgression within and between clades. Morphometric analyses revealed flower symmetry to be a morphological continuum without clear transitions between radial and bilateral symmetry. Tropical Rhododendron species that began diversifying into New Guinea c. 6 million years ago expanded into novel floral morphological space. Our results showed that the evolution of tropical Rhododendron is characterised by recent speciation, recurrent hybridisation and the origin of floral novelty. Floral variation evolved via changes to multiple components of the corolla that are only recognised in geometric morphometrics with both front and side views of flowers

Integration of phylogenomics and molecular modeling reveals lineage-specific diversification of toxins in scorpions

Scorpions have evolved a variety of toxins with a plethora of biological targets, but characterizing their evolution has been limited by the lack of a comprehensive phylogenetic hypothesis of scorpion relationships grounded in modern, genome-scale datasets. Disagreements over scorpion higher-level systematics have also incurred challenges to previous interpretations of venom families as ancestral or derived. To redress these gaps, we assessed the phylogenomic relationships of scorpions using the most comprehensive taxonomic sampling to date. We surveyed genomic resources for the incidence of calcins (a type of calcium channel toxin), which were previously known only from 16 scorpion species. Here, we show that calcins are diverse, but phylogenetically restricted only to parvorder Iurida, one of the two basal branches of scorpions. The other branch of scorpions, Buthida, bear the related LKTx toxins (absent in Iurida), but lack calcins entirely. Analysis of sequences and molecular models demonstrates remarkable phylogenetic inertia within both calcins and LKTx genes. These results provide the first synapomorphies (shared derived traits) for the recently redefined clades Buthida and Iurida, constituting the only known case of such traits defined from the morphology of molecules

Drymonia tomentulifera, sp. nova de Costa Rica, y notas sobre la biología reproductiva del género Drymonia (Gesneriaceae: Episcieae)

A new species of the neotropical genus Drymonia, D. tomentulifera, is described and illustrated, and compared to D. pilifera. Notes on the reproductive biology, especially the widespread occurrence of protandry in the genus Drymonia are included. Se describe e ilustra una nueva especie del género neotropical Drymonia, D. tomentulifera, y se compara con D. pilifera. Se incluyen notas sobre la biología reproductiva del género Drymonia, con énfasis en la protandria.

Una nueva especie y un nuevo registro de Drymonia (Gesneriaceae) en Costa Rica

Se describe Drymonia glandulosa Kriebel, una nueva especie que habita en las bajuras del norte de la vertiente caribe de Costa Rica, y se compara con D. conchocalyx. Drymonia mortoniana Wiehler se reconoce como especie válida y representa un nuevo registro en la flora del país. Drymonia glandulosa Kriebel, a new species restricted to the northern Caribbean lowlands of Costa Rica is described and compared to D. conchocalyx. Drymonia mortoniana Wiehler is recognized as a distinct species and its presence in Costa Rica is a new record for the country’s flora.

A Monograph of Conostegia (Melastomataceae, Miconieae)

A recent molecular phylogenetic analysis identified a clade containing all species of Conostegia, but that also included species of Clidemia and Miconia nested inside. A taxonomic revision of a more broadly circumscribed Conostegia is presented here. In total, 77 species of Conostegia are recognized. One species from Ecuador, C. ortizae is described as new. Twenty-nine new combinations are proposed for the species of Clidemia and Miconia that fall inside Conostegia. Two new names are proposed for the two species for which the epithet was previously occupied in Conostegia. An infrageneric classification of Conostegia is proposed recognizing three sections based on the results of the molecular phylogeny. This taxonomic revision includes ample documentation of the anatomy and morphology of most species in the genus, taxonomic descriptions, a dichotomous key, and distribution maps for all species

NOTES ON THE FLORAL MORPHOLOGY AND ANATOMY OF TESSMANNIANTHUS CARINATUS (MELASTOMATACEAE)

This work reports the second collection of Tessmannianthus carinatus Almeda, a species previously known only from the type. Two flowering trees were encountered at the type locality of Cerro Jefe, Panama . Species in this genus are very rare and the colors and posture of fresh floral parts have seldom been observed and described. The first known images of flowers at anthesis are here provided. In addition, observations on the posture and color of the stamens were made, including dissections of a flower preserved in spirit, and scanning electron micrographs of the unusual anther apices. Lastly, anatomical sections were conducted of these flowers which revealed the presence of styloids in the hypanthium, anthers and styles. These crystals had only been reported from the wood of one species in the genus and their presence suggests a relationship to the tribes Astronieae and Henrietteeae

Phylogeny, taxonomy and morphological evolution in Conostegia (Melastomataceae: Miconieae)

The genus Conostegia comprises 77 species of shrubs and trees ranging from Central America to northern South America and the Caribbean. They are ecologically important as they provide pollen for native bees and fruits for birds. One of the main questions of this study is if the genus Conostegia is actually monophyletic. I address this question for the first time by gathering genetic data from four chloroplast regions and two nuclear ribosomal regions of DNA. Phylogenetic analyses of these data revealed that Conostegia is not monophyletic and that a group of species in the genera Clidemia and Miconia fall within it. It is noteworthy that species of these genera that fall within Conostegia are for the most part restricted to southern Central America. Morphological studies that include the use of anatomy, morphometrics, as well as different types of microscopy were conducted to attempt and identify potential characters that support a more broadly circumscribed Conostegia. These studies revealed several characters such as structured variation in herkogamy, a stele within the style and presence of mucilage inside the ovary in many species as potential synapomorphies for clades within the Conostegia clade. Not only are some of these characters useful but also novel in the systematics of the family Melastomataceae. Having identified a broader Conostegia clade, a taxonomic revision was conducted, including ample documentation of the morphology of all the species in the clade, descriptions and maps for 77 species. Lastly, taking advantage of the results of the molecular phylogeny as guidance, three main hypotheses were tested using morphometric approaches. The first hypothesis stated that diversification in floral morphology had indeed occurred within the Conostegia clade, all species of which are buzz pollinated. It has been said in the past that groups in which buzz pollination has evolved, tend to conserve their floral morphology and pollinators. That being said, no study has addressed how conserved flowers in these lineages actually are. This question was addressed by quantifying floral morphology over a broad sample of species within the Conostegia clade and found four major floral types. Transitions between floral types and their possible biological significance are discussed. The second hypothesis that was tested was that leaf venation in Conostegia is in fact quantifiable using geometric morphometrics and that such variation has a phylogenetic component. Variation in leaf venation, in particular the position of origin of the main parallel veins that characterize the family, has been historically used to distinguish groups of species. These different types of leaf veins have also been proposed as potential synapomorphies for major clades within the family. Possibly because variation in leaf venation is a continuous character, its use in Melastomataceae systematics has been difficult. A general framework is here proposed and it is shown that geometric morphometrics is an efficient tool for grasping leaf venation. In addition, it is shown that one of the three major clades in Conostegia is in fact different in its leaf venation from the other two clades and that the other two clades are similar to each other. The third and last hypothesis tested was that seeds in Conostegia can be quantified using elliptic Fourier analysis (EFA). The latter is a powerful geometric morphometric technique based on outlines. Traditionally, seeds in the Melastomataceae have been used in the systematics of many groups in a qualitative framework by coding binary or multistate discrete variables. For the first time a continuous framework using EFA was attempted. The results show that EFA can efficiently quantify many seeds in a small amount of time and summarize their variation using multivariate statistics in few axes. Furthermore, the EFA analyses revealed that one of the clades within Conostegia is significantly different than the other two but that the latter two are not different between each other. These results corroborate, in a different structure, the results obtained in the leaf venation analyses. In conclusion, identifying a natural or monophyletic group allowed for a revision of the taxonomy of a noteworthy component of Neotropical forests providing a tool to the general public for their identification. Subsequently, having clarity with respect to the relationships and identity of the species within the clade, biological questions were addressed experimenting with new available tools. This process yielded several discoveries

A Widespread New Species in the Neotropical Berry-fruited Genus Clidemia and Range Extension of Ossaea quadrisulca (Melastomataceae: Miconieae)

Volume: 57Start Page: 587End Page: 59

Two new species and one new name in the Gesneriaceae from Costa Rica

Volume: 106Start Page: 43End Page: 5