Variation In Leaf Morphology Research Articles

The effects of environmental heterogeneity on the morphological similarity of toothed-leafed red oak species (Acutifoliae; <i>Quercus</i>) in Mexico and Central America

Background: In plants, environmental gradients can promote similar morphophysiological traits in species that inhabit areas with similar climatic conditions. Here, to evaluate possible causes of morphological similarity, we analyzed leaf morphological and functional variation in toothed-leaf oaks and its relationships with environmental and geographic variables. Hypotheses: We expected that species with a greater degree of environmental overlap would exhibit similar leaf morphology, and those with a broader range of environmental tolerance would exhibit greater leaf morphological variation. Studied species: Acutifoliae group (Fagaceae, Quercus) Study sites and dates: Leaf samples were collected from adult trees distributed in diverse forest types between 495 and 2,566 meters above sea level (m asl) in Mexico and Guatemala. Methods: We compared patterns of leaf variation in a total of 2,934 leaves from 640 individuals corresponding to 68 populations of ten oak species using univariate and multivariate analyses. We also characterized the environmental conditions where each of the species occurred using the available geographical records and bioclimatic variables. Results: We found morphological overlap in leaf traits in oak species occurring in similar climatic environments. Additionally, oak species with a greater range of environmental distributions showed greater leaf shape morphological variation. Conclusions: The environment influenced the generation of similar leaf morphologies among oak species despite geographical distance and phylogenetic relationships.

Intraspecific variation in leaf morphology of three widespread woody species along climatic gradients

Abstract The variation and plasticity of leaf morphology plays a pivotal role in the response to environmental changes for plant individuals. Discovering the large-scale pattern of such variation can reveal plants' general adaptive strategies. We analyzed leaf morphology of three widespread woody species in the northern hemisphere using specimen data from the iDigBio and GBIF databases, to investigate the variations in the individual mean traits, in the inter- and intra-individual variability of traits, and in the allometry between traits, along climatic gradients. We found that larger and wider leaves were associated with warmer, wetter and low-sunlight habitats, while smaller but wider leaves are linked to higher wind speed, indicating the response of leaf morphology to multiple climate stresses. The inter-individual variation in leaf area was smaller in colder and windier conditions, suggesting the trait convergence among individuals under environmental filtering, while the intra-individual variation in leaf relative width was smaller in warmer habitats, indicating the similar growth optimum of leaves within one individual in more favorable conditions. Finally, the allometric exponent between leaf length (X-axis) and width (Y-axis) became greater under lower solar radiation and higher wind speed, while the squared correlation coefficient (r2) indicating phenotypic integration showed a decoupling trend under colder conditions, indicating that climate affected the variation tendency of leaf relative width during leaf enlargement. These results reveal the common patterns of leaf morphology responding to climate variation spatially and underscore the necessity to consider inter- and intra-individual variability when examining plant responses to environmental changes.

Genetic Evidence of SpGH9A3 in Leaf Morphology Variation of Spathiphyllum 'Mojo'.

Leaves play a crucial role as ornamental organs in Spathiphyllum, exhibiting distinct differences across various Spathiphyllum varieties. Leaf development is intricately linked to processes of cell proliferation and expansion, with cell morphology often regulated by plant cell walls, primarily composed of cellulose. Alterations in cellulose content can impact cell morphology, subsequently influencing the overall shape of plant organs. Although cellulases have been shown to affect cellulose levels in plant cells, genetic evidence linking them to the regulation of leaf shape remains limited. This study took the leaves of Spathiphyllum 'Mojo' and its somatic variants as the research objects. We screened four cellulase gene family members from the transcriptome and then measured the leaf cellulose content, cellulase activity, and expression levels of cellulase-related genes. Correlation analysis pinpointed the gene SpGH9A3 as closely associated with leaf shape variations in the mutant. Green fluorescent fusion protein assays revealed that the SpGH9A3 protein was localized to the cell membrane. Notably, the expression of the SpGH9A3 gene in mutant leaves peaked during the early spread stage, resulting in smaller overall leaf size and reduced cellulose content upon overexpression in Arabidopsis.

YOLOv7-Branch: A Jujube Leaf Branch Detection Model for Agricultural Robot.

The intelligent harvesting technology for jujube leaf branches presents a novel avenue for enhancing both the quantity and quality of jujube leaf tea, whereas the precise detection technology for jujube leaf branches emerges as a pivotal factor constraining its development. The precise identification and localization of jujube leaf branches using real-time object detection technology are crucial steps toward achieving intelligent harvesting. When integrated into real-world scenarios, issues such as the background noise introduced by tags, occlusions, and variations in jujube leaf morphology constrain the accuracy of detection and the precision of localization. To address these issues, we describe a jujube leaf branch object detection network based on YOLOv7. First, the Polarized Self-Attention module is embedded into the convolutional layer, and the Gather-Excite module is embedded into the concat layer to incorporate spatial information, thus achieving the suppression of irrelevant information such as background noise. Second, we incorporate implicit knowledge into the Efficient Decoupled Head and replace the original detection head, enhancing the network's capability to extract deep features. Third, to address the issue of imbalanced jujube leaf samples, we employ Focal-EIoU as the bounding box loss function to expedite the regression prediction and enhance the localization accuracy of the model's bounding boxes. Experiments show that the precision of our model is 85%, which is increased by 3.5% compared to that of YOLOv7-tiny. The mAP@0.5 value is 83.7%. Our model's recognition rate, recall and mean average precision are superior to those of other models. Our method could provide technical support for yield estimation in the intelligent management of jujube orchards.

Variation in leaf morphology and architecture, phytochemical content, and antioxidant capacity among 36 Camellia sinensis clones of the Indian sub-Himalayan region

Camellia sinensis, renowned as the second most widely consumed nonalcoholic beverage worldwide, bears substantial economic importance, prompting cultivators to breed various clones for enhanced flavor and quality. This study analyzed the variation in leaf phenotype, phytochemicals (total tannins and proanthocyanidins content) and antioxidant potential of 36 widely cultivated tea clones from India’s sub-Himalayan region using multivariate analysis. Results indicated that TV23 had the largest leaf and SS27 and RR had the smallest. TS520 was the richest in tannin, proanthocyanidins, and antioxidants, while S3A1 and Heeleakah were the least. Principal components analysis (PCA) and cluster analysis unveiled four morphological clusters (representative clones - TV1, TV23, TV30, 124.48.8) and four phytochemical clusters (representative clones - TS520, TV9, TV27, P126). GC-MS analysis revealed that TV1 and TV30 had high caffeine content (82.0%), while TS520 exhibited abundant antioxidant compounds, including sycllo-inositol (23.84%) and epigallocatechin (4.23%). TS520’s exceptional antioxidant properties, confirmed by DPPH, ABTS, and total antioxidant capacity assays, may result from its cultivation through seed propagation. Correlation analysis showed antioxidant potential had moderate negative associations with leaf size, strong negative with inter-secondary vein number, and positive with petiole length. This study is pivotal for assessing tea clone diversity, with broader applications in tea improvement and breeding programs.

Leaf morphological variation in Betula medwediewii Regel populations from Türkiye

Leaf variations of Betula medwediewii in Türkiye with respect to its distribution pattern were studied because this plant taxon is a Euxine element and a distinct relict species in Türkiye. In this context, the aim of this study is to investigate variations in leaf morphological characteristics within and among B. medwediewii populations in natural distribution areas in Türkiye. Thus, the morphological leaf characteristics of four populations of B. medwediewii growing at different elevations spanning from 1472 to 2065 m.a.s.l in two cities (Artvin and Rize) and four boroughs (Arhavi, Borçka, Murgul, and Çamlıhemşin) of Türkiye were analyzed. The four populations were selected based on their natural distribution and 1,200 leaf samples belonging to 40 individuals were measured with ImageJ. According to the results of correlation analysis, statistically significant relationships were determined among morphological leaf characteristics. Mean values for petiole length (1.16 cm), leaf width (5.11 cm), leaf length (7.96 cm), length of lamina (6.79 cm), leaf area (26.62 cm²), leaf vein angle (54.21°), and number of primary leaf veins (20.03) were determined in all populations. Because B. medwediewii contributes to biodiversity and can preserve the ecological stability of the Turkish forest area, its conservation is crucial.

Plant biology: Managing age-related bursts during leaf development

Age-dependent control of the miR165-regulated SPL transcription factor circuitry is responsible for the variation in leaf morphology over time. A new study reveals the underlying morphogenetic dynamics.

Species identification through deep learning and geometrical morphology in oaks (Quercus spp.): Pros and cons.

Plant phenotypic characteristics, especially leaf morphology of leaves, are an important indicator for species identification. However, leaf shape can be extraordinarily complex in some species, such as oaks. The great variation in leaf morphology and difficulty of species identification in oaks have attracted the attention of scientists since Charles Darwin. Recent advances in discrimination technology have provided opportunities to understand leaf morphology variation in oaks. Here, we aimed to compare the accuracy and efficiency of species identification in two closely related deciduous oaks by geometric morphometric method (GMM) and deep learning using preliminary identification of simple sequence repeats (nSSRs) as a prior. A total of 538 Asian deciduous oak trees, 16 Q. aliena and 23 Q. dentata populations, were firstly assigned by nSSRs Bayesian clustering analysis to one of the two species or admixture and this grouping served as a priori identification of these trees. Then we analyzed the shapes of 2328 leaves from the 538 trees in terms of 13 characters (landmarks) by GMM. Finally, we trained and classified 2221 leaf-scanned images with Xception architecture using deep learning. The two species can be identified by GMM and deep learning using genetic analysis as a priori. Deep learning is the most cost-efficient method in terms of time-consuming, while GMM can confirm the admixture individuals' leaf shape. These various methods provide high classification accuracy, highlight the application in plant classification research, and are ready to be applied to other morphology analysis.

Patterns of Leaf and Fruit Morphological Variation in Marginal Populations of Acer tataricum L. subsp. tataricum.

Marginal populations are usually smaller and more isolated and grow in less favourable conditions than those at the distribution centre. The variability of these populations is of high importance, as it can support the adaptations needed for the conditions that they grow in. In this research, the morphological variability of eight Tatar maple (Acer tataricum L. subsp. tataricum) populations was analysed. Tatar maple is an insect-pollinated and wind-dispersed shrub/tree, whose northwestern distribution edge is in southeastern Europe. Morphometric methods were used to analyse the variability of the populations using leaf and fruit morphology. The research revealed significant differences between and within populations. Furthermore, differences in the distribution of the total variability were noted, which suggest that different evolutionarily factors affect different plant traits. Correlation analysis confirmed a weak dependency between the vegetative and generative traits. In addition, no evidence was found for the presence of isolation by environment (IBE). However, the Mantel test for isolation by distance (IBD) was significant for the leaf morphometric traits and non-significant for the fruit morphometric traits. Being the marginal leading-edge populations, they are younger and were less likely to have had time for adaptation to local environments, which would have resulted in the development of IBE. Overall, edge populations of Tatar maple were characterised by great morphological variability, which helps these populations in their response to the intensive selective pressures they face in their environment.

In Vitro Regeneration from Leaf Explants of Helianthus verticillatus, a Critically Endangered Sunflower.

Helianthus verticillatus (Asteraceae), a whorled sunflower, is a perennial species restricted to a few locations in the southeastern United States and is now considered endangered. Therefore, restoring and protecting H. verticillatus as a species is a priority. This study introduces a highly efficient in vitro adventitious plant regeneration system from leaf explants, utilizing five diverse specimens of H. verticillatus, each representing distinct genotypes with phenotypic variations in leaf and stem morphology. Key factors influencing in vitro morphogenesis, including genetic constitution, explant source, and plant growth regulators (PGRs), were identified. The study revealed a remarkably strong genotype-dependent impact on the regeneration efficiency of the investigated H. verticillatus genotypes, ranging from a lack of regeneration to highly effective regeneration. The selection of two genotypes with varying regeneration abilities provides valuable models for genetic analyses, offering insights into factors influencing the regeneration potential of this endangered species. Optimum adventitious shoot regeneration results were achieved using Murashige and Skoog basal media (MS) supplemented with 8.8 µM N6-benzyladenine (BA) and 1.08 µM α-naphthalene acetic acid (NAA). This combination yielded the highest adventitious shoot production. Subsequent successful rooting on ½ MS medium without PGRs further solidified the efficiency of the developed protocol. Regenerated plantlets, demonstrating robust shoots and roots, were successfully acclimatized to greenhouse conditions with a 95% survival rate. The protocol developed in this study is the first such report for this endangered species and is expected to contribute to future genetic manipulation and modification studies.

Functional trait divergence associated with heteromorphic leaves in a climbing fig.

Plants that display heteroblasty possess conspicuous variations in leaf morphology between their juvenile and adult phases, with certain species retaining juvenile-like leaves even in adulthood. Nevertheless, the ecological advantages of maintaining two or more distinct leaf types in heteroblastic plants at the adult stage remain unclear. The aim of this study is to examine the adaptive significance of heteroblastic leaves sampled from branches with divergent functions (sterile and fertile branches) of mature Ficus pumila individuals by comparing their morphological, anatomical, and physiological characteristics. Leaves on sterile branches (LSs) exhibited a significantly larger specific leaf area, thinner palisade and spongy tissues, lower chlorophyll contents, and lower light saturation points than leaves on fertile branches (LFs). These results demonstrate that LSs are better adapted to low light environments, while LFs are well equipped to take advantages of high light conditions. However, both LFs and LSs have a low light compensation point with no significant difference between them, indicating that they start to accumulate photosynthetic products under similar light conditions. Interestingly, significant higher net photosynthetic rate was detected in LFs, showing they have higher photosynthetic capacity. Furthermore, LFs produced significant more nutrients compared to LSs, which may associate to their ability of accumulating more photosynthetic products under full light conditions and higher photosynthetic capacity. Overall, we observed a pattern of divergence in morphological features of leaves on two functional branches. Anatomical and physiological features indicate that LFs have an advantage in varied light conditions, providing amounts of photosynthetic products to support the sexual reproduction, while LSs adapt to low light environments. Our findings provide evidence that heteroblasty facilitates F. pumila to utilize varying light environments, likely associated with its growth form as a climbing plant. This strategy allows the plant to allocate resources more effectively and optimize its overall fitness.

JUNGLE RUBBER AND PIONEER TREE: INVESTIGATING LEAF MORPHOLOGICAL VARIATION OF Alstonia scholaris R. BR. IN JAMBI

Human activity has reduced natural forests in Indonesia and triggered their transformation into, for example, jungle rubber land, as is often found in the Jambi Province of Central Sumatera. Forming jungle rubber through successional processes involves important pioneer trees such as Alstonia scholaris. The pioneer species' performance is influenced by site factors, the initial biodiversity status, cultivation treatment, and management inputs. The study reported here was conducted to assess leaf morphological variation of A. scholaris as preliminary indicators of difference in response and growth performance in several CRC990 plots (50 m x 50 m) of two distinct landscapes: Bukit Dua Belas National Park and Harapan Rain Forest. Results of the analysis of variance showed that the difference in landscapes gave rise to a significant effect on leaf morphology variable NV (venation number) for A. scholaris. Differences between plots within the landscapes were significant in the variables venation number (NV) and petiole ratio (PR) for A. Scholaris. The results of the distribution of leaf morphological variation in A. scholaris based on multivariate analyses (PCA) showed no clustering due to landscape effects.

Tetraploid Induction with Leaf Morphology and Sunburn Variation in Sorbus pohuashanensis (Hance) Hedl

Sorbus pohuashanensis (Hance) Hedl. is an important forestry species valued for its ornamental, medicinal, and ecological properties. Polyploidy breeding is an important method of germplasm innovation; however, polyploidy induction and phenotypic variation caused by chromosome doubling in S. pohuashanensis are poorly understood. In this study, S. pohuashanensis seeds were used to explore the effects of different colchicine concentrations, cold stratification times, and seeds from different sources on polyploidy induction. Ploidy levels of the regenerated plants were determined by flow cytometry. The results showed that the tetraploid induction effect of S. pohuashanensis seeds was significantly affected by colchicine concentration, and the highest tetraploid induction rate of 24.75% was achieved by immersion in 0.2% (w/v) colchicine for 48 h. After 2 years of induction, 77 tetraploid plants were obtained. Compared to diploids, tetraploid plants showed significant variations in plant height, leaf morphology (apical leaflet width, middle leaflet width), and diameter of the middle petiole. The stomatal size and chloroplast number increased with chromosome doubling whereas the stomatal number and density decreased. In addition, significant differences in the percentage of sunburn associated with ploidy changes were observed. This study provides a technique for tetraploid induction of S. pohuashanensis seeds, showing the variation in traits caused by polyploidization and the effect of chromosome doubling on sunburn resistance. Tetraploidy induction provides a new direction for S. pohuashanensis germplasm innovation.

Geographical variation of Artemisia leaf morphology along a large environmental gradient in China

Geographical variation of Artemisia leaf morphology along a large environmental gradient in China

Association of photosynthesis of flag leaves with grain yield in pearl millet (Pennisetumglaucum (L.) R. Br.)

The grain yield of pearl millet has increased continuously in past decades through development of hybrids and improved production practices. Elite inbred lines are crucial for innovating new germplasm/traits to break the yield plateau. Hence, 64 inbred lines of pearl millet were evaluated to assess the extent of genetic variability and association among agronomic, physiological and grain yield contributing traits. Analysis of variance showed significant differences among the lines for all the traits indicating sufficient variability for genetic exploitation. The preferred arid adaptation traits, early flowering and high tillering were associated with each other making them amenable for simultaneous selection and these two traits were not associated with grain yield. Hence, for deriving ideotypes suitable for arid adaptation, intensive selection for grain yield in early flowering background was suggested. In productive regions, the plants having greater plant height, larger size of leaves including flag leaf, larger panicle size to accommodate the photosynthates are desirable and these traits were found to be associated among themselves and with grain yield in the current study. Though the maximal photosynthetic efficiency, Fv/Fm was significantly associated with leaf length, flag leaf length, flag leaf width and actual PSII efficiency (Y(II)), these physiological parameters did not significantly associate with grain yield directly and their effects are confounded within the leaf morphological variation.

Leaf morphological traits of nine major tropical trees of Shorea species (Dipterocarpaceae)

Abstract. Mufarhatun N, Susilowati A, Hilwan I, Arrofaha N, Yulita KS, Dwiyanti FG, Hidayat A, Kamiya K, Rachmat HH. 2023. Leaf morphological traits of nine major tropical trees of Shorea species (Dipterocarpaceae). Biodiversitas 24: 1704-1712. Shorea is the largest genus in the Dipterocarpaceae family and has high leaf morphological variations among its species, which causes difficulties in field identification. Therefore, information on the specific characteristics of the leaf morphology of each species is needed. This study aimed to examine and discriminate leaf morphological traits at both mature and sapling stages of nine Shorea species, namely Shorea balangeran (Korth.) Burck, S. leprosula Miq., S. mecistopteryx Ridl., S. multiflora (Burck) Symington, S. ovalis (Korth.) Blume, S. pinanga Scheff., S. platyclados Slooten ex Endert, S. selanica (Wight & Arn.) Blume, and S. stenoptera Burck. The leaves of 90 mature trees growing in the Dramaga Research Forest (DRF) and Gunung Dahu Research Forest (GDRF) as well as the leaves of 180 saplings growing in the nursery of Forest Research and Development Center (FRDC) were observed. Leaf traits, leaf color, and chlorophyll content were assessed on 3 leaves from each mature tree and 5 from each sapling collected. Furthermore, comparative analysis using F independent test in the one-way analysis variance (ANOVA), multivariate analysis using Principal Component Analysis (PCA), and Hierarchical Cluster Analysis were used in this study. The results showed that 8 of the 11 measured morphological traits were identified as the quantitative leaves morphological differentiators, namely Leaves Width (LW), Lamina Length (LL), the length between the largest Leaves Point (LP) with the base of the leaves, angle of leaves vein (SD), Petiole Length (PL), number of leaves vein (LB), breadth of the leaves (WL), and the Circumference of the Leaves (CL). In addition, the results of cluster analysis showed the nine Shorea spp. are clustered into two major groups. Group 1 consisted of species, S. stenoptera, and S. mecistopteryx, while the remaining are included in Group 2. Our findings conclude that the eight leaf morphological traits obtained from this study are useful as additional characters to distinguish the nine Shorea species in the field.

QTL Mapping of Leaf-Related Traits Using a High-Density Bin Map in Brassica rapa

The species Brassica rapa includes enormous leafy vegetables with extreme leaf morphological diversity. Leaf traits such as size, shape, weight, and ratio of the leaf blade to the petiole contribute to yield, appearance, and desirability to consumers. These leaf-related traits are controlled by quantitative trait loci (QTLs). The construction of high-density bin maps using low-coverage sequencing is a powerful method for QTL fine-mapping and gene identification. In this study, we performed whole-genome re-sequencing of Wutacai ‘Zhongbaye’ and Chinese cabbage ‘HN53’ and 150 F2 individuals to construct a high-density bin map for QTL mapping of 11 leaf-related traits. The parental lines and F2 population were re-sequenced at 10x and 1x coverage, respectively. A map containing 565 bin markers was constructed based on parental single-nucleotide polymorphisms and a modified sliding window approach. The total map length was 944.6 cM and the average distance of the bins was 1.65 cM. In total, 60 significant QTLs controlling 11 leaf-related traits were detected. We further identified candidate genes responsible for these complex leaf-related traits. These findings suggest that this cost-effective bin-mapping approach is capable of rapid identification of QTLs and candidate genes, and will thus facilitate the dissection of the underlying molecular basis of leaf morphological variations and accelerate the improvement of B. rapa vegetable breeding.

Morpho-metric Analysis of Leaf and Fruit of Selected Mulberry Accessions: A Preliminary Measure for Diversity Analysis

Morus spp. exhibits wide variation in leaf morphology among different species and accessions within the same species. Some of the important silent morphological characteristics pertaining to mulberry leaf and fruit have been selected for the current study. Among all the ten selected genotypes ovate leaf shape was recorded to be the most common ones. Maximum leaf size of leaf was recorded in case of genotype S-1635 as 187cm and minimum in case of Kanva-2 as 28cm. Most of the genotypes were recorded with serrated to parted margins except C-4 with parted margin and smooth leaf texture with exceptions of coarse leaf in C-4, Chinese white and C-2038. Two most common types of leaf apex have been recorded as acuminate and acute with cordate, hastate and truncate leaf base. Maximum leaf length was recorded in S-1635 as 17 cm followed by Chakmajra as 15 cm and S-13 as 14 cm and 7 cm was recorded in C-4 and Kanva-2 and maximum in S-1635 as 11cm followed by S-13 and chakmajra as 8 cm and least in G-4 and Kanva-2 as 4 cm. Similarly maximum actual leaf area was recorded in genotype S-1635 as 71 cm2 and minimum in genotype C-2038 as 19.5 cm2. Fresh and dry weight of the leaf was recorded to be maximum in S-1635 as 11.4 g and minimum in Kanva-2 as 3.5 g and V-1 as 5.2 g respectively. In addition to fresh and dry leaf weight, moisture percentage and moisture retention capacity was recorded to be maximum of 72.4% in C-4 and minimum of 54.26% in S-1635 and maximum moisture retention capacity of 64% was recorded for G-4 genotype and minimum of 50% in C-2038. Maximum stomatal frequency was observed to be highest of 156 mm2 was recorded in S-1635 and least in Chinese white as 84 mm2 and stomatal index of 16% in V-1 and least in genotype S-13 as 11.1% and Cystolyth frequency was observed to be highest S-13 as 52% and minimum in genotype C-2038 as 24%. Thus, the current study could be used by plant breeders for genetic characterization and evaluation of different genotypes.

Leaf morphology affects microplastic entrapment efficiency in freshwater macrophytes

Context In contrast to marine environments, microplastic pollution in freshwater systems is understudied. Previous research suggests that freshwater macrophytes function as microplastic sinks, which, because they are at the base of food webs, has implications for higher trophic levels. Aim This study compares the ability of freshwater plants with different leaf morphologies to trap downwelling microplastics. Method Microplastics (800–1000 μm polyamide grains) were deposited onto three macrophyte species, namely, Cabomba caroliniana, Egeria densa, and Hygrophila polysperma. Microplastic mass retained was calculated as the percentage of microplastic mass captured by the plant and standardised microplastic retention was calculated as the absolute microplastic mass retained (g) divided by plant dry mass (g). Results The amount of trapped microplastics differed significantly among species, with the highest amount trapped by C. caroliniana (39.3%; 7.91 g g−1), followed by E. densa (28.8%; 5.30 g g−1) and H. polysperma (17.6%; 4.47 g g−1). Conclusion Significant differences in microplastic retention among species may be attributed to variation in leaf morphology. Implications These findings have potential applications in bioremediation and biomonitoring, where freshwater macrophytes could help with the tracking and mitigation of microplastics in the environment.

Integrating morphological and genetic limits in the taxonomic delimitation of the Cuban taxa of Magnoliasubsect.Talauma (Magnoliaceae).

An accurate taxa delimitation, based on a full understanding of evolutionary processes involved in taxa differentiation, can be gained from a combination of ecological, morphological, and molecular approaches. The taxonomy of Magnoliasubsect.Talauma in Cuba has long been debated and exclusively based on traditional morphological study of a limited number of individuals. A more accurate description of leaf morphology variation using geometric morphometrics combined with genetic data could bring consistency to taxa delimitation in this group. Leaf samples for the morphological (243) and genetic (461) analyses were collected throughout the entire distribution range. The variability of each taxon was analyzed through multivariate and geometric morphometry, and 21 genetic markers (SSR). The observed leaf morphological variability was higher than previously described. Morphological and genetic classifications were highly congruent in two out of four taxa. Our data brought evidence that Magnoliaorbiculata can be considered a true species with very clear genetic and morphological limits. The main taxonomic issues concern the north-eastern Cuban populations of Magnoliasubsect.Talauma. The data supported the existence of two clear groups: corresponding mainly to M.minor-M.oblongifolia and T.ophiticola. However, these two groups cannot be considered fully delimited since genetic markers provided evidence of genetic admixture between them. Due to the likely absence of, at least strong, reproductive barriers between these three taxa, we propose therefore to consider them as a species complex.