RESUMO
Evolutionary transitions from hermaphroditism to dioecy have been common in flowering plants,1,2 but recent analysis also points to frequent reversions from dioecy to hermaphroditism.2-4 Here, we use experimental evolution to expose a mechanism for such reversions, validating an explanation for the scattered phylogenetic distribution of dioecy. We removed males from dioecious populations of the wind-pollinated plant Mercurialis annua and allowed natural selection to act on the remaining females that occasionally produced male flowers; such "leaky" sex expression is common in both males and females of dioecious plants.5 Over the course of four generations, females evolved a 23-fold increase in average male flower production. This phenotypic masculinization of females coincided with the evolution of partial self-fertilization, high average seed set in the continued absence of males, and a capacity to sire progeny when males were re-introduced into their populations. Our study thus validates a mechanism for the rapid dissolution of dioecy and the evolution of functional hermaphroditism under conditions that may frequently occur during periods of low population density, repeated colonization, or range expansion.6,7 Our results illustrate the power of natural selection, acting in replicated experimental populations, to bring about transitions in the mating behavior of plants.
Assuntos
Evolução Biológica , Organismos Hermafroditas , Magnoliopsida , Filogenia , Reprodução , SolubilidadeRESUMO
The river stingray Potamotrygon orbignyi is a carnivorous bottom feeder that is widespread in the Amazonian region. We here assemble the 17,449 bp complete mitochondrial genome of the species, showing a typical gene arrangement as for related Potamotrygonidae. The analysis of the COI gene confirmed the identification of the specimen as P. orbignyi. A phylogenetic analysis of all Potamotrygonidae complete mitochondrial genomes highlights the close relationship between P. orbignyi and P. motoro.
RESUMO
PREMISE OF THE STUDY: Polymorphic microsatellite markers were developed to study population structure and mating patterns of the monocarpic herb Moricandia moricandioides (Brassicaceae). METHODS AND RESULTS: Illumina MiSeq sequencing was used to develop a panel of 15 polymorphic microsatellite markers that were tested across 77 individuals from three populations on the Iberian Peninsula. All markers were polymorphic in at least two studied populations, and the number of alleles ranged from one to 11 per locus. The levels of observed and expected heterozygosity ranged from 0.000 to 1.000 and from 0.153 to 0.865, respectively. Nine and 11 loci were successfully amplified in the congeneric species M. arvensis and M. foetida, respectively. CONCLUSIONS: The 15 microsatellite markers will be useful for population genetic studies of the genus Moricandia. These markers will serve as a useful tool for exploring population structure and mating patterns of M. moricandioides.
