The characteristics of flowers influence most aspects of angiosperm reproduction, including the agents of pollination and patterns of mating. Thus, a clear view of the forces that mediate floral ...phenotypic evolution is central to understanding angiosperm diversity. Here, we inform on the capacity for floral phenotype to respond to selection by reviewing published data on heritabilities and genetic correlations for several classes of floral traits (primary sexual, attraction, mating system) in hermaphroditic plants. We find significant heritability for all floral traits but also variation among them, as well as a tendency for heritability to vary with mating system, but not life history. We additionally test predictions stemming from life history theory (eg, negative covariation between male-female traits and flower size-flower number), and ideas concerning the extent and pattern of genetic integration between flowers and leaves, and between the sexes of dioecious and gynodioecious species. We find mixed evidence for life history tradeoffs. We find strong support for floral integration and its relation with floral morphology (actinomorphy vs zygomorphy) and for a decoupling of floral and vegetative traits, but no evidence that modular integration varies with floral morphology. Lastly, we find mixed evidence for a relationship between the level of sexual dimorphism in attraction traits and the between-sex correlation in gender dimorphic plants.
Many recent studies attempting to assess the biochemical connections between anthocyanin biosynthesis and floral scent production have yielded limited insights due in part to a focus on either field ...phenotypes of unknown genetic background or artificial genetic manipulation. In this study, we seek to more precisely explore the mechanistic connections between floral scent and color in
Ipomoea purpurea by comparing inbred lines of wild-type purple flowered plants to lines of two naturally occurring color mutants: albino individuals created by a chalcone synthase (
A locus) loss-of-function mutation and rayed individuals that result from a non-functional transcription factor (
W locus). We found that
I. purpurea floral scent is dominated by the two sesquiterpene hydrocarbons, (
E)-β-caryophyllene and germacrene D, with small amounts of several other sesquiterpenoid compounds. These 15 carbon volatiles are derived from the mevalonic acid biosynthetic pathway, which has no structural precursor relationship with anthocyanin pigments. Thus, there is no direct pleiotropic relationship and, accordingly, we found no differences in overall scent production between purple-flowered and albino individuals. In contrast, rayed plants showed greater emission of several compounds when compared to their wild-type counterparts, suggesting that the specific mutant regulatory region in this phenotype could have an indirect effect on volatile production either through changes to overall metabolic flux or alteration of sesquiterpene synthase gene expression or enzyme activity. Future research should explore these possible roles for transcription factors across multiple biochemical pathways. There were no differences in floral scent composition or emission rate between the offspring of parents from the same line, suggesting that scent phenotype was conserved within each inbred line. However, there were differences in floral scent between inbred lines, suggesting that a number of genetic elements must contribute to overall scent production in this species.
An outbreak of haemorrhagic fever with renal syndrome (HFRS) started on Medvednica mountain near Zagreb in January 2012. In order to detect the aetiological agent of the disease in small rodents and ...to make the link with the human outbreak, rodents were trapped at four different altitudes. Using nested RT–PCR, Puumala virus (PUUV) RNA was detected in 41/53 (77·4%) bank voles (Myodes glareolus) and Dobrava virus (DOBV) RNA was found in 6/61 (9·8%) yellow-necked mice (Apodemus flavicollis). Sequence analysis of a 341-nucleotide region of the PUUV S segment, obtained from all infected bank voles and five HFRS patients, showed 98·8–100% sequence similarity, indicating that the patients were probably exposed to PUUV on Medvednica mountain. A very large bank-vole population combined with an extremely high infection rate of PUUV was responsible for this unusual winter outbreak of HFRS in Croatia.
Chemical communication is ubiquitous. The identification of conserved structural elements in visual and acoustic communication is well established, but comparable information on chemical ...communication displays (CCDs) is lacking.
We assessed the phenotypic integration of CCDs in a meta-analysis to characterize patterns of covariation in CCDs and identified functional or biosynthetically constrained modules.
Poorly integrated plant CCDs (i.e. low covariation between scent compounds) support the notion that plants often utilize one or few key compounds to repel antagonists or to attract pollinators and enemies of herbivores. Animal CCDs (mostly insect pheromones) were usually more integrated than those of plants (i.e. stronger covariation), suggesting that animals communicate via fixed proportions among compounds. Both plant and animal CCDs were composed of modules, which are groups of strongly covarying compounds. Biosynthetic similarity of compounds revealed biosynthetic constraints in the covariation patterns of plant CCDs.
We provide a novel perspective on chemical communication and a basis for future investigations on structural properties of CCDs. This will facilitate identifying modules and biosynthetic constraints that may affect the outcome of selection and thus provide a predictive framework for evolutionary trajectories of CCDs in plants and animals.
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