Phylogeny and biogeography of the American live oaks ( Quercus

The nature and timing of evolution of niche differentiation among closely related species remains an important question in ecology and evolution. The American live oak clade, Virentes, which spans the unglaciated temperate and tropical regions of North America and Mesoamerica, provides an instructive system in which to examine speciation and niche evolution. We generated a fossil-calibrated phylogeny of Virentes using RADseq data to estimate divergence times and used nuclear microsatellites, chloroplast sequences and an intron region of nitrate reductase (NIA-i3) to examine genetic diversity within species, rates of gene flow among species and ancestral population size of disjunct sister species. Transitions in functional and morphological traits associated with ecological and climatic niche axes were examined across the phylogeny. We found the Virentes to be monophyletic with three subclades, including a southwest clade, a southeastern US clade and a Central American/Cuban clade. Despite high leaf morphological variation within species and transpecific chloroplast haplotypes, RADseq and nuclear SSR data showed genetic coherence of species. We estimated a crown date for Virentes of 11 Ma and implicated the formation of the Sea of Cortés in a speciation event ~5 Ma. Tree height at maturity, associated with fire tolerance, differs among the sympatric species, while freezing tolerance appears to have diverged repeatedly across the tropical-temperate divide. Sympatric species thus show evidence of ecological niche differentiation but share climatic niches, while allopatric and parapatric species conserve ecological niches, but diverge in climatic niches. The mode of speciation and/or degree of co-occurrence may thus influence which niche axis plants diverge along

Sugar and Polyphenolic Diversity in Floral Nectar of Cherry

Cherries (Prunus avium L. and Prunus cerasus L.) are economically important fruit species in the temperate region. Both are entomophilous fruit species, thus need pollinators to give high yields. Since cherry’s flower is easy-to-reach, bees and other pollinators can smoothly collect nectar as a reward for doing transfer of pollen to receptive stigma. Nectar in cherry is usually attractive for insects, especially to honey bee (Apis mellifera) who is the most common pollinator. Nectar is predominantly an aqueous solution of sugars, proteins, and free amino acids among which sugars are the most dominant. Trace amounts of lipids, organic acids, iridoid glycosides, minerals, vitamins, alkaloids, plant hormones, non-protein amino, terpenoids, glucosinolates, and cardenolides can be found in nectar too. Cherry flower may secrete nectar for 2–4 days and, depending on the cultivar, produces up to 10 mg nectar with sugar concentration from 28% to 55%. Detailed chemical analysis of cherry nectar described in this chapter is focused on sugar and phenolic profile in sour cherry. The most abounded sugars in cherry nectar was fructose, glucose, and sucrose, while arabinose, rhamnose, maltose, isomaltose, trehalose, gentiobiose, turanose, panose, melezitose, maltotriose, isomaltotriose, as well as the sugar alcohols glycerol, erythritol, arabitol, galactitol, and mannitol are present as minor constituents. Regarding polyphenolics, rutin was the most abundant phenolic compound followed by naringenin and chrysin. Cherry cultivars showed different chemical composition of nectar which implies that its content is cultivar dependent