Climate explains population divergence in drought-induced plasticity of functional traits and gene expression in a South African Protea.

Long-term environmental variation often drives local adaptation and leads to trait differentiation across populations. Additionally, when traits change in an environment-dependent way through phenotypic plasticity, the genetic variation underlying plasticity will also be under selection. These processes could create a landscape of differentiation across populations in traits and their plasticity.

Correlated evolution between climate and suites of traits along a fast-slow continuum in the radiation of .

Evolutionary radiations are responsible for much of Earth's diversity, yet the causes of these radiations are often elusive. Determining the relative roles of adaptation and geographic isolation in diversification is vital to understanding the causes of any radiation, and whether a radiation may be labeled as "adaptive" or not. Across many groups of plants, trait-climate relationships suggest that traits are an important indicator of how plants adapt to different climates.

Transcriptome sequencing reveals population differentiation in gene expression linked to functional traits and environmental gradients in the South African shrub Protea repens.

Understanding the environmental and genetic mechanisms underlying locally adaptive trait variation across the ranges of species is a major focus of evolutionary biology. Combining transcriptome sequencing with common garden experiments on populations spanning geographical and environmental gradients holds promise for identifying such mechanisms. The South African shrub Protea repens displays diverse phenotypes in the wild along drought and temperature gradients.

Intraspecific variation in stomatal traits, leaf traits and physiology reflects adaptation along aridity gradients in a South African shrub.

Background And Aims: Trait-environment relationships are commonly interpreted as evidence for local adaptation in plants. However, even when selection analyses support this interpretation, the mechanisms underlying differential benefits are often unknown. This study addresses this gap in knowledge using the broadly distributed South African shrub Protea repens.

Extrapolating from local ecological processes to genus-wide patterns in colour polymorphism in South African Protea.

Polymorphic traits are central to many fundamental discoveries in evolution, yet why they are found in some species and not others remains poorly understood. We use the African genus Protea-within which more than 40% of species have co-occurring pink and white floral colour morphs-to ask whether convergent evolution and ecological similarity could explain the genus-wide pattern of polymorphism. First, we identified environmental correlates of pink morph frequency across 28 populations of four species.

Functional Traits in Parallel Evolutionary Radiations and Trait-Environment Associations in the Cape Floristic Region of South Africa.

Evolutionary radiations with extreme levels of diversity present a unique opportunity to study the role of the environment in plant evolution. If environmental adaptation played an important role in such radiations, we expect to find associations between functional traits and key climatic variables. Similar trait-environment associations across clades may reflect common responses, while contradictory associations may suggest lineage-specific adaptations.

Developmental plasticity in Protea as an evolutionary response to environmental clines in the Cape Floristic Region.

Local adaptation along steep environmental gradients likely contributes to plant diversity in the Cape Region of South Africa, yet existing analyses of trait divergence are limited to static measurements of functional traits rather than trajectories of individual development. We explore whether five taxa of evergreen shrubs (Protea section Exsertae) differ in their developmental trajectories and capacity for plasticity using two environmentally-distinct common gardens in South Africa. We measured seedlings in the summer-dry season and winter-wet season of each of two consecutive years to characterize ontogeny and plasticity within years, as same-age leaf cohorts mature, and between years, i.

Direct and indirect selection on floral pigmentation by pollinators and seed predators in a color polymorphic South African shrub.

The coexistence of different color morphs is often attributed to variable selection pressures across space, time, morph frequencies, or selection agents, but the routes by which each morph is favored are rarely identified. In this study we investigated factors that influence floral color polymorphisms on a local scale in Protea, within which approximately 40% of species are polymorphic. Previous work shows that seed predators and reproductive differences likely contribute to maintaining polymorphism in four Protea species.

Natural selection on inflorescence color polymorphisms in wild Protea populations: The role of pollinators, seed predators, and intertrait correlations.

Premise Of The Study: The processes maintaining flower color polymorphisms have long been of evolutionary interest. Mechanistic explanations include selection through pollinators, antagonists, local environments, drift, and pleiotropic effects. We examined the maintenance of inflorescence color polymorphisms in the genus Protea (Proteaceae) of South Africa, in which ∼40% of species contain different color morphs.

Plant responses to climate in the Cape Floristic Region of South Africa: evidence for adaptive differentiation in the Proteaceae.

Local adaptation along environmental gradients may drive plant species radiation within the Cape Floristic Region (CFR), yet few studies examine the role of ecologically based divergent selection within CFR clades. In this study, we ask whether populations within the monophyletic white protea clade (Protea section Exsertae, Proteaceae) differ in key functional traits along environmental gradients and whether differences are consistent with local adaptation. Using seven taxa, we measured trait-environment associations and selection gradients across 35 populations of wild adults and their offspring grown in two common gardens.

Hummingbird responses to gender-biased nectar production: are nectar biases maintained by natural or sexual selection?

Pollinators mediate the evolution of secondary floral traits through both natural and sexual selection. Gender-biased nectar, for example, could be maintained by one or both, depending on the interactions between plants and pollinators. Here, I investigate pollinator responses to gender-biased nectar using the dichogamous herb Chrysothemis friedrichsthaliana (Gesneriaceae) which produces more nectar during the male floral phase.

The benefits of bathing buds: water calyces protect flowers from a microlepidopteran herbivore.

Protective floral structures may evolve in response to the negative effects of floral herbivores. For example, water calyces--liquid-filled, cup-like structures resulting from the fusion of sepals--may reduce floral herbivory by submerging buds during their development. Our observations of a water-calyx plant, Chrysothemis friedrichsthaliana (Gesneriaceae), revealed that buds were frequently attacked by ovipositing moths (Alucitidae), whose larvae consumed anthers and stigmas before corollas opened.

Male-biased nectar production in a protandrous herb matches predictions of sexual selection theory in plants.

Nectar production may disproportionately benefit male relative to female pollination success. In such cases, sexual selection is often suggested as the cause of asymmetric benefits, yet sexual selection in plants-particularly plants with hermaphroditic flowers-is infrequently tested empirically. Here, I used a protandrous herb with male-biased nectar production (Chrysothemis friedrichsthaliana, Gesneriaceae) to test predictions from sexual selection theory.

Synergistic inhibitory effects of gastrin and histamine receptor antagonists on Helicobacter-induced gastric cancer.

Background & Aims: Apart from its importance as an acid secretogogue, the role of histamine as a downstream target of gastrin has not been fully explored. Previous studies have shown that the combination of hypergastrinemia and Helicobacter infection resulted in accelerated gastric cancer in mice. We used this model to examine the role of cholecystokinin 2 (CCK2)/gastrin receptor and histamine H2-receptor signaling in the development of gastric atrophy and cancer.

Intrinsic hematopoietic stem cell/progenitor plasticity: Inversions.

Traditional concepts indicate that stem cells give rise to progenitor cells in a hierarchical system. We studied murine engraftable stem cells (ESCs) and progenitors in in vitro and found that ESC and progenitors exist in a reversible continuum, rather then a hierarchy. B6.

Rhythmicity of engraftment and altered cell cycle kinetics of cytokine-cultured murine marrow in simulated microgravity compared with static cultures.

Space flight with associated microgravity is complicated by "astronaut's anemia" and other hematologic abnormalities. Altered erythroid differentiation, red cell survival, plasma volume, and progenitor numbers have been reported. We studied the impact of microgravity on engraftable stem cells, culturing marrow cells in rotary wall vessel (RWV) culture chambers mimicking microgravity and in normal gravity nonadherent Teflon bottles.

Engraftment of post 5-fluorouracil murine marrow into minimally myeloablated (100 cGy) murine hosts.

Minimal myeloablative approaches are now being widely applied in the treatment of different hematological malignancies. One hundred cGy whole-body irradiation is a stem-cell-toxic, relatively non-myelotoxic treatment that allows for relatively high levels of donor chimerism. 5-Fluorouracil (5-FU) treatment leads to a relative concentration of high proliferative potential-colony-forming cell (HPP-CFC) and is an approach that has been used to induce in vivo progenitor/stem cell cycling to facilitate retroviral integration in gene therapy approaches.