Non‐continuous reproductive phenology of animal‐dispersed species in young forest restoration plantings

Tree species that produce resources for fauna are recommended for forest restoration plantings to attract pollinators and seed dispersers; however, information regarding the flowering and fruiting of these species during early growth stages is scarce. We evaluated the reproductive phenology of animal‐dispersed tree species widely used in Atlantic Forest restoration. We marked 16 animal‐dispersed tree species in 3‐ to 8‐year‐old forest restoration plantings in Itu‐São Paulo, southeast Brazil. We noted the age of the first reproductive event, flowering and fruiting seasonality, percentage of trees that reached reproductive stages, and intensity of bud, flower, and fruit production for each species. Flowering and fruiting are seasonal for most species; only two, Cecropia pachystachya and Ficus guaranitica, exhibited continuous flowering and fruiting throughout the year; we also identified Schinus terebinthifolia and Dendropanax cuneatus fruiting in the dry season during resource scarcity. Therefore, we recommend all as framework species, that is, species that are animal‐dispersed with early flowering and fruiting potential, for forest restoration. Further, we recommend identifying and planting similar animal‐dispersed tree species that produce fruits constantly or in the dry season to maximize fauna resource availability throughout the year in tropical forest restoration plantings. Abstract in Portuguese is available with online material     

Phylogenetic and ecological correlates of pollen morphological diversity in a Neotropical rainforest

Morphology varies enormously across clades, and the morphology of a trait may reflect ecological function or the retention of ancestral features. We examine the tension between ecological and phylogenetic correlates of morphological diversity through a case study of pollen grains produced by angiosperms in Barro Colorado Island, Panama (BCI). Using a molecular phylogeny of 730 taxa, we demonstrate a statistically significant association between morphological and genetic distance for these plants. However, the relationship is non‐linear, and while close relatives share more morphological features than distant relatives, above a genetic distance of ~ 0.7 increasingly distant relatives are not more divergent in phenotype. The pollen grains of biotically pollinated and abiotically pollinated plants overlap in morphological space, but certain pollen morphotypes and individual morphological traits are unique to these pollination ecologies. Our data show that the pollen grains of biotically pollinated plants are significantly more morphologically diverse than those of abiotically pollinated plants. Abstract in Spanish is available with online material.     

A geographical perspective on the relationship between Impatiens spur lengths and bill lengths of sunbirds in Afrotropical mountains

Trait matching—a correlation between the morphology of plants and their pollinators—has been frequently observed in pollination interactions. Different intensities of natural selection in individual regions should cause such correlations to be observable across different local assemblages. In this study, we focused on matching between spur lengths of the genus Impatiens and bill lengths of sunbirds in tropical Africa. For 25 mountain and island locations, we compiled information about the composition and traits of local Impatiens and sunbird assemblages. We found that assemblage mean and maximum values of bill lengths were positively correlated with mean and maximum spur lengths across locations. Moreover, our results suggest that the positive correlations hold only for forest sunbird assemblages sharing the same habitat with Impatiens species. We further show that long‐billed sunbirds seem to locally match the morphology of multiple Impatiens plant species, not vice versa. Our observation implies that trait matching significantly contributes to structuring of Impatiens–sunbird pollination systems. We suggest that special habitat preferences together with spatial isolation of mountain environment might play a role in this case.     

Optimization of the nutritional environment for differentiation of human-induced pluripotent stem cells using design of experiments—A proof of concept

The utilization of human-induced pluripotent stem cells (hiPSCs) in cell therapy has a tremendous potential but faces many practical challenges, including costs associated with cell culture media and growth factors. There is an immediate need to establish an optimized culture platform to direct the differentiation of hiPSCs into germ layers in a defined nutritional microenvironment to generate cost-effective and robust therapeutics. The aim of this study was to identify the optimal nutritional environment by mimicking the in vivo concentrations of three key factors (glucose, pyruvate, and oxygen) during the spontaneous differentiation of hiPSCs derived from cord blood, which greatly differ from the in vitro expansion and differentiation scenarios. Moreover, we hypothesized that the high glucose, pyruvate, and oxygen concentrations found in typical growth media could inhibit the differentiation of certain lineages. A design of experiments was used to investigate the interaction between these three variables during the spontaneous differentiation of hiPSCs. We found that lower oxygen and glucose concentrations enhance the expression of mesodermal (Brachyury, KIF1A) and ectodermal (Nestin, β-Tubulin) markers. Our findings present a novel approach for efficient directed differentiation of hiPSCs through the manipulation of media components while simultaneously avoiding the usage of growth factors thus reducing costs.     

Effects of experimental shifts in flowering phenology on plant-pollinator interactions

Climate change has led to phenological shifts in flowering plants and insect pollinators, causing concern that these shifts will disrupt plant-pollinator mutualisms. We experimentally investigated how shifts in flowering onset affect pollinator visitation for 14 native perennial plant species, six of which have exhibited shifts to earlier flowering over the last 70 years and eight of which have not. We manipulated flowering onset in greenhouses and then observed pollinator visitation in the field. Five of six species with historically advanced flowering received more visits when flowering was experimentally advanced, whereas seven of eight species with historically unchanged flowering received fewer visits when flowering earlier. This pattern suggests that species unconstrained by pollinators have advanced their flowering, whereas species constrained by pollinators have not. In contrast to current concern about phenological mismatches disrupting plant-pollinator mutualisms, mismatches at the onset of flowering are not occurring for most of our study species.     

Culture conditions' impact on succinate production by a high succinate producing Escherichia coli strain

This work aimed to identify the key operational factors that significantly affect succinate production by the high succinate producing Escherichia coli strain SBS550MG (pHL413), which bears mutations inactivating genes adhE ldhA iclR ackpta::Cm(R) and overexpresses the pyruvate carboxylase from Lactococcus lactis. The considered factors included glucose concentration, cell density, CO(2) concentration in the gas stream, pH, and temperature. The results showed that high glucose concentrations inhibited succinate production and that there is a compromise between the total succinate productivity and succinate specific productivity, where the total productivity increased with the increase in cell density and the specific productivity decreased with cell density, probably due to mass transfer limitation. On the other hand, a CO(2) concentration of 100% in the gas stream showed the highest specific succinate productivity, probably by favoring pyruvate carboxylation, increasing the OAA pool that later is converted into succinate. A full factorial design of experiments was applied to analyze the pH and temperature effects on succinate production in batch bioreactors, where succinate yield was not significantly affected by either temperature (37 to 43°C) or pH (6.5 to 7.5). Additionally, the temperature effect on succinate productivity and titer was not significant, in the range tested. On the other hand, a pH of 6.5 showed very low productivity, whereas pH values of 7.0 and 7.5 resulted in significantly higher specific productivities and higher titers. The increase on pH value from 7.0 to 7.5 did not show significant improvement. Then, pH 7.0 should be chosen because it involves a lower cost in base addition.     

A Geographic Mosaic of Plant–Pollinator Interactions in the Eastern Caribbean Islands

The interplay between generalized and specialized plant–animal interactions is a core concept in understanding the evolution of mutualisms. Within the Eastern Caribbean, Heliconia bihai is a dominant forest species in the southern island of St. Vincent where H. caribaea is virtually absent. Heliconia caribaea is most common on the northern island of St. Kitts where H. bihai is restricted to the tops of the highest peaks. Both species are abundant on the central island of Dominica. We compared flowering patterns, nectar characteristics, and visitation frequency of hummingbirds in the two heliconias on the three islands to determine the extent of geographic variations in this plant–pollinator mutualism. The peak flowering season of the two heliconias was observed to be in April–May on all three islands with little within‐ and between‐island variations. Nectar production significantly varied between species and between islands. Visitation patterns by the principal hummingbird pollinators also varied between the islands: (1) on Dominica, only females of a single species of hummingbird pollinated the flowers of H. bihai (sexual specialization), whereas both sexes of the same hummingbird pollinated the flowers of H. caribaea (species specialization); (2) on St. Vincent, both sexes of the same hummingbird pollinated the flowers of H. bihai (species specialization); and (3) on St. Kitts, only females pollinated the flowers of H. bihai (sexual specialization), whereas several species of hummingbird visited the flowers of H. caribaea (species generalization). We propose that the Heliconia–hummingbird interactions in the Eastern Caribbean represent a geographically variable coevolutionary mosaic of plant–pollinator interactions.