Striking between-population floral divergences in a habitat specialized plant

When the habitat occupied by a specialist species is patchily distributed, limited gene flow between the fragmented populations may allow population differentiation and eventual speciation. ‘Sky islands’—montane habitats that form terrestrial islands—have been shown to promote diversification in many taxa through this mechanism. We investigate floral variation in Impatiens lawii, a plant specialized on laterite rich rocky plateaus that form sky islands in the northern Western Ghats mountains of India. We focus on three plateaus separated from each other by ca. 7 to 17 km, and show that floral traits have diverged strongly between these populations. In contrast, floral traits have not diverged in the congeneric I. oppositifolia, which co-occurs with I. lawii in the plateaus, but is a habitat generalist that is also found in the intervening valleys. We conducted common garden experiments to test whether the differences in I. lawii are due to genetic differentiation or phenotypic plasticity. There were strong differences in floral morphology between experimental plants sourced from the three populations, and the relative divergences between population pairs mirrored that seen in the wild, indicating that the populations are genetically differentiated. Common garden experiments confirmed that there was no differentiation in I. oppositifolia. Field floral visitation surveys indicated that the observed differences in floral traits have consequences for I. lawii populations, by reducing the number of visitors and changing the relative abundance of different floral visitor groups. Our results highlight the role of habitat specialization in diversification, and corroborates the importance of sky islands as centres of diversification.

Too many species: morphometrics, molecular phylogenetics and genome structure of a Brazilian species complex in Epidendrum (Laeliinae; Orchidaceae) reveal fewer species than previously thought

In this study, we analyse a species complex in Epidendrum, a mega-diverse Neotropical orchid genus, that is formed by the 11 Brazilian species of the E. difforme group. Although this group (c. 100 taxa) exhibits relatively high levels of floral variation, the Brazilian species are similar, making delimitation problematic. Here we combine molecular (phylogenetics), morphological (geometric morphometrics), genome size and cytogenetic (chromosome counts and CMA/DAPI staining) data to investigate circumscription of these species. Our results were interpreted by looking for congruence of the results as a means to delimit species. The studied taxa appear to be monophyletic, and karyotypically all analysed accessions were 2n = 40. Their 1C values vary from 1.99 ± 07 pg to 2.84 ± 0.12 pg. We did not find evidence for recent polyploidy or dysploidy and, apparently, these phenomena have not been important in the evolution of this species complex. On the other hand, we found high levels of polymorphism for CMA/DAPI banding, and variation in genome size appears to be positively correlated with latitude. Geometric morphometrics indicate that E. sanchezii and E. anatipedium/E. amarajiense are distinct from the remaining species, and three groups of other species can be separated using canonical variables analysis (CVA). Variation in lip shape, genome size and heterochromatin patterns of the taxa are not fully congruent with the phylogenetic analysis, but our results allowed us to delimit with full confidence four species: E. amapense, E. anatipedium (including E. amarajiense), E. pseudodifforme (including E. campaccii and E. thiagoi) and E. sanchezii. Four others will be tentatively maintained but need further study. Our results indicate that it will be necessary to reassess many of the species complexes in the genus using a similar multidisciplinary perspective to evaluate the number of taxa that should be recognized.

Homeosis and delayed floral meristem termination could account for abnormal flowers in cultivars of Delphinium and Aquilegia (Ranunculaceae)

Floral mutants display various deviant phenotypes and, as such, they are appropriate material with which to address the origin and the building of morphological variation. To identify the pivotal developmental stages at which floral variation may originate and to infer the putative associated genetic causes, we studied abnormal flowers in nine cultivars of Aquilegia and Delphinium of Ranunculaceae, a family displaying a high range of floral diversity. Wild-type flowers of the two genera are pentamerous and spurred, but they differ in their overall symmetry (actinomorphy vs. zygomorphy). Floral morphology of their cultivars at different developmental stages up to anthesis was observed, and the putative identity of the perianth organs and vascularization was inferred. Our results show that in the floral mutants in both genera, phyllotaxis was generally conserved, whereas floral organization, vascularization and symmetry were modified. Most of the morphological and anatomical deviations impacted the perianth, including organ number, identity and (spur) elaboration, and also led to the formation of mosaic organs. We hypothesized that the phenotypes of floral mutants in Aquilegia and Delphinium result from genetic alterations affecting frontiers between sets of organs of different identity, homeosis and length of floral meristem activity.

Application of CRISPR/Cas9 genome editing system for molecular breeding of orchids

Orchid is an important ornamental plant in Indonesia due to their natural beauty of flowers. In the tropical forest, orchids are being acquired for trading and commercial market. Thus, the effort is required to proliferate orchid in large quantities for conservation and improve the floral variation for plant breeding. The purpose of this study is to develop a firmed methodology of molecular breeding of orchids using CRISPR/Cas9 KO system. The plant material used was Phalaenopsis amabilis protocorms growth on NP medium+pepton (2 g/L). Protocorm were submerged in the culture of Agrobacterium tumefaciens that Ti‐plasmid had been filled with a T‐DNA construct of a pRGEB32 vector harboring sgRNA with PDS3 sequence. Detection for transformants was confirmed by PCR using HPT primers (545 bp), Cas9 primers (402 bp), PDS primers (280 bp) and trnL‐F (1200 bp) as an internal control. The results showed that 0.96% PDS transformants were obtained from PDS3T2 lines. Several transformant showed pale leaf color compared to non‐transformant plants. This study suggests that the target gene has successfully edited by CRISPR/Cas9 system and could be applied for that functional gene editing in orchids.

The influence of floral variation and geographic disjunction on the evolutionary dynamics of Ronnbergia and Wittmackia (Bromeliaceae: Bromelioideae)

The Ronnbergia alliance is a lineage of two genera, Ronnbergia and Wittmackia, which diversified in three centres of distribution; the Pacific Forest, the Atlantic Forest and the Caribbean. In this study, we reconstructed the most plausible biogeographic scenario that explain the disjunct evolution of the Ronnbergia alliance in these centres of diversity. We also compared the evolutionary rate dynamics of lineage diversification and floral evolution in each of these areas. Our results suggested that the Ronnbergia alliance originated in the Atlantic Forest c. 5.2 Mya. Ronnbergia originated c. 3.5 Mya after a long-distance dispersal event to the Pacific Forest. The diversification of Wittmackia started in the Atlantic Forest, c. 3.2 Mya, and experienced more heterogeneous evolutionary rate dynamics than Ronnbergia during its radiation. In Wittmackia a long-distance dispersal from the Atlantic Forest to Jamaica gave rise to the Caribbean clade, which diversified rapidly and experienced significantly higher rates of floral evolution. This study helped in understanding how bromeliad diversification occurs differently among major centres of biodiversity. In our case, we found how the Caribbean is a much more dynamic area of diversification than the Atlantic Forest or the Pacific Forest.

Patterns of floral morphology in relation to climate and floral visitors

Background and Aims The diversity of floral morphology among plant species has long captured the interest of biologists and led to the development of a number of explanatory theories. Floral morphology varies substantially within species, and the mechanisms maintaining this diversity are diverse. One possibility is that spatial variation in the pollinator fauna drives the evolution of spatially divergent floral ecotypes adapted to the local suite of pollinators. Another possibility is that geographic variation in the abiotic environment and local climatic conditions favours different floral morphologies in different regions. Although both possibilities have been shown to explain floral variation in some cases, they have rarely been competed against one another using data collected from large spatial scales. In this study, we assess floral variation in relation to climate and floral visitors in four oil-reward-specialized pollination interactions. Methods We used a combination of large-scale plant and pollinator samplings, morphological measures and climatic data. We analysed the data using spatial approaches, as well as traditional multivariate and structural equation modelling approaches. Key Results Our results indicate that the four species have different levels of specialization, and that this can be explained by their climatic niche breadth. In addition, our results show that, at least for some species, floral morphology can be explained by the identity of floral visitors, with climate having only an indirect effect. Conclusions Our results demonstrate that, even in very specialized interactions, both biotic and abiotic variables can explain a substantial amount of intraspecific variation in floral morphology.

Palynology of the Cenomanian Raha Formation, Gulf of Suez, Egypt: Biostratigraphical, palaeoenvironmental and palaeobiogeographical implications

The current study presents a fully qualitative palynological investigation carried out on the Raha Formation encountered from three wells in the Bakr Oil Field of the Gulf of Suez, Egypt. Around 30 species of pteridophytic spores, 26 species of angiosperm pollen, 24 species of gymnosperm pollen and 27 species of dinoflagellate cysts have been recorded. However, achritarchs, microforaminiferal test linings and freshwater algae are impoverished and sparsely documented throughout the Raha Formation. Two palynozones have been identified based on some stratigraphically significant pollen and spores, arranged from youngest to oldest: (1) Palynozone I (Classopollis brasiliensis–Tricolpites sagax Assemblage Zone) of late Cenomanian age; (2) Palynozone II (Afropollis jardinus–Crybelosporites pannuceus Assemblage Zone) of early-middle Cenomanian age. The distribution and ecological affiliation of specific palynomorph species, as well as various palynofacies parameters, are interpreted. A shallow marine environment from supratidal to distal inner neritic under proximal suboxic–anoxic to dysoxic–anoxic shelf conditions is reconstructed. Palaeobiogeographically, the absence of elaters from the recovered taxa is interpreted in terms of minor floral variation. This may be attributed to climatic and/or an environment-controlled niche establishment, which possibly was shaped by the existence of a physical barrier hindering the distribution of such type of elaterate parent plants.

Evaluating the Genetic Structure of Camissoniopsis cheiranthifolia in California Dune Restorations

Habitat loss and fragmentation is considered the largest cause of decreasing biodiversity. Previously, preservation was the main method of mitigating the human impact; however, with decreasing pristine habits, there has been a shift towards ecological restoration. The California coastal dunes have been the sites of many restorations. One native species that has been planted in restorations is the iconic beach evening primrose (Camissoniopsis cheiranthifolia). With a distinct floral variation across its range, C. cheiranthifolia seeds must be carefully sourced when restoring dunes. But has it? I evaluated 22 restored site and 12 natural sites by collecting tissue samples, floral measurements, and fruit counts. Using DNA and floral markers, it is possible to determine whether large flowers from the south have been planted in the north or vice versa. The DNA markers can even determine if individuals of the same flower size have been used outside of their populations. I used fruit counts as an indicator of fitness, which will allow me to be able to determine whether restorations using non-local plants are detrimental to the plants’ well-being. I expect to find mismatches in both DNA and floral markers in restoration sites compared to local natural sites accompanied by a decrease in fitness. Hopefully, the results of this study will allow for stricter regulations on sourcing of restoration material.