Plant Systematics and Evolution最新文献

Plant individuals respond to distinct environmental conditions, which can drive morphological variation. Conversely, intraindividual floral variation affects interactions with pollinators and plant fitness. In distyly, population-level variation has been seen as negative since morph reciprocity in stigma and anther heights promotes precise cross-pollination. However, although natural selection occurs at the individual level, we still do not know how sexual structures vary within individuals in the floral morphs of distylous populations. We used typically distylous populations of Neotropical Rubiaceae family as model systems to study intraindividual variation. Based on the morphology of sexual structures, we calculated the coefficients of variation of heights and size (lengths) as a measure of intraindividual variation (IIV). Stigmas of thrum morph (stigma below anthers) had higher IIV in height when compared to their respective anthers and the stigmas and anthers of pin morph (stigma above anthers). On the other hand, the IIV in size was higher in the stigmas of both morphs when compared to anthers. Higher variation/imprecision in anthers and stigmas affect reciprocal herkogamy and hinder precise pollination both at population and individual levels. However, we suggest that higher variations in stigma heights and sizes may be an intraindividual strategy to occupy a greater positional range, which would increase the chances of cross-pollen deposition among its flowers. This would adjust flowers to the different pollinator guilds, which probably exert different selective pressures. Our study offers a new perspective on distylous flowers, suggesting that IIV may increase pollen reception and explain imprecision at the population level.

Festuca makutrensis is an assumed tetraploid species of F. valesiaca agg. described from West Ukraine. However, its current interpretation seems misleading, as it is mostly based on the protologue and opinions of Russian authors, lacking knowledge of the type material and the locus classicus. Here, we collected robust population samples (20–30 plants per population) of known F. makutrensis populations in Ukraine (including locus classicus) and Eastern Poland, along with morphologically similar hexaploids, F. rupicola and F. trachyphylla (65 populations in total). We conducted measurements on 1553 flowering plants to analyze their morphology and examined 4439 leaves in cross section to observe their anatomy. Additionally, we determined ploidy in a selected subset of 61 plants using flow cytometry. Contrary to existing works, our findings unequivocally demonstrate that F. makutrensis is a hexaploid taxon. It closely resembles F. rupicola, with the only distinguishing feature being the ever-present, well-developed additional sclerenchyma strands on the leaf cross section. These strands can occasionally fuse with other strands and form irregular sclerenchyma rings in some (> 25%) plants within the population. The distribution of F. makutrensis appears to be limited to Northwest Podolia and Zhytomyr Polissia in Ukraine, as well as the Lublin Voivodeship in Eastern Poland. Reported occurrences of this taxon outside these regions are considered doubtful.

The Neotropic is known as the most botanically species-rich region, and Croton is one of the richest angiosperm genera in this region. Here, we describe and illustrate a new species of Croton from the “Parque Estadual do Cantão,” located in state of Tocantins state, northern Brazil. The new species is classified based on morphological, anatomical and molecular data. Croton cantoensis sp. nov. is morphologically and anatomically related to Croton section Cleodora, and this hypothesis was supported by the results of our phylogenetic analyses, in which the new species emerged in Croton section Cleodora subsection Sphaerogyni. Croton cantoensis differs from other species from the section by its branchlets covered by ochre floccose indumentum, branchlets and petioles with scattered ferrugineus trichomes, petioles sometimes blackish and pistillate flowers with scattered ferrugineus trichomes. This new species increases the number of members of Croton section Cleodora to 28.

Lasiosiphon Fresen. (Thymelaeaceae: Thymelaeoideae) is now understood to be a morphologically diverse genus distributed across southern and tropical Africa, Madagascar, and India. It is diagnosed morphologically by ± involucrate, mostly pedunculate heads of pentamerous or tetramerous flowers, with or without petaloid scales, and a bright yellow, orange, or red corolla. The taxonomic history of Lasiosiphon has been marked by several revisions in its circumscription and status, particularly regarding its relationship with Gnidia L. Our phylogenetic analysis of nuclear (ITS) and plastid (matK, rbcL, rps16 and trnL-F) regions of an expanded sampling of the tropical African species of Gnidia provides compelling supporting evidence for existing morphological evidence to include all the tropical African species of Gnidia in Lasiosiphon. We accordingly provide 31 new combinations in Lasiosiphon for species of Gnidia that currently lack combinations in that genus. We also provide a comprehensive nomenclator of all currently recognized Lasiosiphon species at the regional level encompassing their distribution across different geographic regions globally. This will serve as the framework for future taxonomic revisions in the genus.

Whole-genome duplication (WGD) is a leading force of plant sympatric speciation. However, the evolutionary mechanisms promoting the establishment of neopolyploid mutants in nature remain elusive. We studied polyploid establishment in a unique natural system of Mimulus guttatus (Phrymaceae) in Shetland where a recently (< 100 years ago) locally formed autotetraploid still coexists with its diploid progenitor. We cytotyped 679 adults and 766 seedlings and scored relevant reproductive traits in the field and performed controlled crossings to infer differences in plant performance and get a first insight into the crossing barriers between ploidies. Tetraploids grew in 25% of Shetland populations, mostly in mixtures with diploids, but triploids were absent both among seedlings and adults. Seeds of both cytotypes sampled in areas of immediate sympatry exhibited similar, high germination rates (98% on average). In contrast, low (2%) germination of progeny from controlled interploidy crosses demonstrated strong postzygotic isolation. Yet, plants simultaneously pollinated by diploid and tetraploid pollen donors set viable progeny with ploidy levels identical to the seed parent. The abundant presence of fertile tetraploids in the field despite strong postzygotic isolation demonstrates the ability of novel autopolyploids to cope with both intrinsic and extrinsic challenges associated with WGD and to successfully establish in nature.

The Crocus gargaricus complex (Iridaceae) is known from a handful of scattered populations and three taxa from Turkey. The relationship between these taxa and their taxonomic state, however, has remained controversial for the past 200 years. Crocus gargaricus was described from Mount Ida in 1841 and later a geographically distant population was discovered at Göktepe, Muğla. The closely related C. thirkeanus, which was considered a synonym for about 40 years until 1984 when it was elevated to subspecies level as C. gargaricus subsp. herbertii, was known only from Uludağ. The latest molecular methods have now shown C. thirkeanus and C. gargaricus to be distinct species. However, one major limitation of previous studies was their heavy reliance on cultivated material. This study examines all known populations of the C. gargaricus complex, collected from their type locations, as well as two more recently discovered populations (Kütahya and İzmir). We combine morpho-anatomical measurements, statistical data analyses and molecular phylogeny to help resolve the relationships between these taxa across their known ranges. Our analysis revealed a clear division of the six populations into three taxa: C. gargaricus, C. thirkeanus and C. cigdemiae, a new species described herein.

Hydrangea sect. Macrophyllae comprises deciduous shrubs including two species with seven infraspecific taxa distributed throughout the Japanese Archipelago and adjacent areas. In this study, we revealed a phylogeny of Hydrangea sect. Macrophyllae by using a larger dataset of genome-wide SNPs than those employed in a previous study and by adding more comprehensive taxa/populations, which cover the entire distribution of the section. We then revised the taxonomic treatment of sect. Macrophyllae based on the higher-resolution phylogenetic trees obtained in this study. The phylogenetic trees estimated in this study showed five major clades, suggesting that H. serrata var. minamitanii and var. yesoensis should be treated as independent species from other H. serrata, that H. serrata var. australis and var. yakushimensis could be subclassified under the major clades and that var. angustata could be a synonym of var. serrata. The divergence time of these major clades was estimated to be in the Pleistocene.

Plant reproduction may experience distinct evolutionary and ecological dynamics depending on their flowering phenology. Consequently, floral traits might undergo divergence selection to adapt to the difference in the abiotic and the biotic environment, especially if these traits affect intensity of competition plants experience due to pollinators. The present study analyzed the plant floral display, floral rewards, and the pollination and breeding systems of two related species of Leucojum, the autumn-blooming L. autumnale and the spring-blooming L. trichophyllum. The aim of the current study is to compare reproductive aspects of L. autumnale and L. trichophyllum due to differing environmental conditions. Both species needed pollinators to reproduce sexually, with zero (L. trichophyllum) or low values (c. 7.7%; L. autumnale) for fructification after self-pollination vs. over 90% after natural pollination (both species). Their flowers opened in the morning and closed at night, and neither produced nectar, only pollen as reward to pollinators. Plants of the L. autumnale studied population produced 1–4 inflorescences per plant vs. only 1 in L. trichophyllum, and the former presented a greater density of flowers per surface unit. Leucojum autumnale flowers were visited by Hymenoptera and those of L. trichophyllum only by two Coleoptera, which were most abundant at sunrise and sunset, whereas in the middle of the day, they visited Cistaceae flowers. This latter occurrence may represent a temporal niche partitioning rather than competition in relation to visiting hours, as the L. trichophyllum flowers offer a place for insects to spend the night, a period in which the flowers of the Cistaceae species have lost their petals.

Originally described as an acaulescent species, the Butia archeri complex currently comprises two varieties. Butia archeri var. archeri has a wide distribution and both acaulescent and caulescent populations, while B. archeri var. diamantinensis is a microendemic represented only by caulescent individuals. Here, we compared the morpho-anatomy of two caulescent populations, one of each variety, with the acaulescent B. archeri from the typus locality (Lavras). Butia archeri from Lavras have shorter inflorescence axis and prophyll, similar-sized flowers, raphides in the pinnae, and accessory bundles surrounding the fibrous ring completely. Revolute bracts and fibres in the expansion tissue are exclusive of B. archeri var. diamantinensis, which, allied to the geographical isolation, clearly supports a new status and combination: Butia diamantinensis. The caulescence and lax rachillae allied to anatomical differences, show that Brasília’s population, formerly B. archeri var. archeri, is not B. archeri. Our results showed that the main diagnostic characters of B. archeri are lacking in the studied caulescent populations, warranting the rejection of the taxon’s amended descriptions. Furthermore, our study highlights the urgent need for further investigation into other taxa currently classified under B. archeri, particularly those facing extinction threats in the Cerrado. Here, we underpin the relevance of circumscriptions based on reliable characters to understand variable taxa, which impact conservation policies.

Species are fundamental biological units and can be treated as testable scientific hypotheses. Historically, species in the genus Coccoloba have been published based only on classical morphology. One of these species, Coccoloba laevis, contains many specimens with strong morphological differences. We here test the hypothesis that these morphological variations are consistent with the circumscription of C. laevis as a single taxonomic entity. In addition to classical morphology, we used linear morphometry, vascular anatomy, and potential geographic distribution to delineate a distinctive morphotype of C. laevis from the remainder of C. laevis s.s. Statistical analysis showed significant differences for all ten morphometric variables. Petiole and midrib anatomy also pointed to differences in both shape and arrangement of vascular bundles between the distinctive morphotype and the remainder of C. laevis s.s. The potential distribution model yielded a wide distribution for C. laevis s.s. in the coastal zone of northeastern Brazil. The distinctive morphotype, however, had a contiguous and restricted distribution within this range. Based on our results, we here reestablish Coccoloba candolleana at the species level, which has been previously treated as a synonym of C. laevis. Both species differ morphologically mainly by habit, and the shape and size of ochrea, leaf, petiole, inflorescence, pedicel, and fruit. Because of its restricted distribution in a coastal ecosystem associated with strong anthropogenic disturbance, we consider C. candolleana as endangered.